Sediments Of The Southern California Mainland Shelf

PDF

Download

Open document

Flip pages

Download a page range

Download transcript

Copy asset link

Request this asset

Request accessible transcript

Transcript (if available)

Content This dissertation has been 64— 13,514 m icrofilmed exactly as received WIMBERLEY, Stanley, 1927- SEDIMENTS OF THE SOUTHERN CALIFORNIA MAINLAND SHELF. University of Southern California, Ph.D., 1964 Geology University Microfilms, Inc., Ann Arbor, Michigan SEDIMENTS 0? THE SOUTHERN CALIFORNIA MAINLAND SHELF by Stanley Vlmberley A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (Geology) June 1904 UNIVERSITY OF SO U TH ER N CALIFORNIA GRADUATE SCHOOL UNIVERSITY PARK L O S ANOELES 7 . CALIFORNIA This dissertation, written by Stanlsj WImberley under the direction of hiM...Dissertation Com mittee, and approved by all its members, has been presented to and-accepted by the Graduate School, in partial fulfillment of requirements for the degree of DOCTOR OF PHILOSO PHY ... D«u June 1964.......... DISSERTATION COMMITTEE PIZASB w m t Figure page* are not original copy. They tend to "curl”. Filmed in the beat way poeoible. University Microfilms, Inc. ABSTHACT The narrow submerged margin of the continent off southern California receives coarse land-derived sediment carried by rivers If a sediment supply 1b available. Where rivers or sediment supply are lacking* the mainland shelf remains free of modern sediments, leaving exposed on the sea floor materials which were deposited under former environmental conditions or outcrops of bedrock. A submerged prodelta of modem sediments has been built off the mouth of Santa Clara Blver, as Indloated by a smooth seaward bulge of topographic contours and radial decrease in sediment grain size. A trough-like depression between the prodelta and a 20-foot linear shelf-rise resulting from exposed bedrock provides a settling basin for accumulation of sediments finer than elsewhere on the mainland shelf. The shelf-rise area contrasts greatly with the depression area in having coarse-grained sediments with characteristics that suggest reworking of shelf bedrook in place• Bsbayments near Santa Monica and San Pedro have areas of exposed basement rook and areas of modem sedi ments along shoreward margins. Surfaoe materials of San Pedro and San Diego Shelves are mostly relict deposits remaining from post-glacial rise of sea level. The inter vening region is a narrow shelf less than 4 miles wide Ill where rivers debouch sediments from the Santa Ana Mountains. These materials have blanketed that part of the shelf with modern sediments showing seaward decreasing grain size gradation. Average median diameter of mainland shelf sediments is 0.060 mm, in the coarse silt size class. This value, however, Is Intermediate between coarse relict deposits averaging 0.107 mm in non-depositlonal areas and modern sediments averaging 0.041 mm off the mouth of Santa Olara Hiver. Other average values for the mainland Bhelf are: standard deviation, 1.00 phl-unlts; first phi skewness, 0.20; second phi skewness, 1.16, and Sorting Coefflolent, 1. 6. Sediments in general are coarser in the vicinity of major headlands than elsewhere, coarser on those flanks of submarine canyons which approaching waves first encounter, and coarser downstream of canyon lncisements. Average grain size, sorting, and skewness have a degree of inter dependence. Trends of sediment sorting and skewness differentiate between modem detrltal materials and older deposits of former environments. CONTENTS Page INTRODUCTION............................. 1 Topography ..... .... 2 Regional geology ..... ......... ... 3 Previous investigations ....... ..... 5 Purpose of this study •••...••.•. 8 Acknowledgment a .................. 9 FIELD AND LABORATORY PROCEDURES........... 11 Field collection........................ 11 Laboratory analysis.................... 11 PROPERTIES OF THE SEDIMENTS............... 19 Sediment texture ........................ 19 Sediment type........................ 19 Median diameter .................... 27 Sorting ........................... 36 Skewness............................. 37 Sand content.......................... 56 Silt content.......................... 68 Clay content ....... 68 Gravel content ...................... 75 Chemical properties .................... 75 Organic matter and nitrogen content ... 75 Calcium carbonate content ........ 82 V Page MAINLAND SHELF SEDIMENTARY UNITS..... 84 Point Conception Narrow-shelf complex ... 84 Carpinterla Shelf-rise deposit ........... 89 Santa Clara Prodelta deposit ............. 92 LaB Pitas Mud deposit............ 94 Santa Monica Shelf complex ........... 98 San Pedro Shelf complex.......... 105 Oceanside Narrow-shelf complex • ••••.. 109 San Diego Shelf complex ..... ........ 113 Nearshore environment ................... 118 GENERALIZATIONS ABOUT THE MAINLAND SHELF ... 121 Sediment variation with time....... 121 Santa Monica Bay ......... 122 San Pedro Shelf .........••••• 125 San Diego Shelf ................. 126 Geographical generalizations......... 127 Shelf width.................... 127 Sediment sources................ 128 Influence of submarine canyons ...... 129 Regional characteristics ............... 134 Influenoe of headlands ................. 139 Zonation of sediments • • • • ... 142 Statistical generalizations ............. 144 Parameter interrelationships •••..•• 144 Vi Page SUMMARY................................. 150 REFERENCES............................... 161 APPENDIX................................. 165 ILLUSTRATIONS Figure 1. Ft* Arguello to Santa Barbara# sample locations........• ............... 2. Santa Barbara to Point Dume, sample locations ••• ........ ,«•••. S. Point Duma to Newport# sample.locations 4* Newport to La Jolla# sample locations • 5. La Jolla to Mexico# sample locations , • 6. Classification of sediment types • « • • 7. Pt. Arguello to Santa Barbara# sediment types ■ 8. Santa Barbara to Point Dume# sediment types ............................. 9. Point Dume to Newport# sediment types • 10. Newport to Mexico# sediment types • * • 11. Histogram of median diameters , • • • • 12. Pt, Arguello to Santa Barbara# median diameters • ................. 13. Santa Barbara to Point Dume# median diameters ........ ,««,,» 14. Santa Monica Bay# median diameter (mm) , 16, Median diameter (men.), San Pedro , , • , 16, Newport to Mexico# median diameters • • viii Figure Peg# 17. Median diameter (non)# San Diego • • • • • 35 18. Pt. Arguello to Santa Barbara, sorting— phi standard deviation • • • • 58 19. Santa Barbara to Point Dume, eorting— phi standard deviation • • • • 39 20. Santa Monloa Bay, sorting— phi standard deviation • •••••••••••••• 40 21. Sorting— phi standard deviation, San Pedro • •••••••••••••• 41 22. Sorting— phi standard deviation, Newport to Mexico .......... ••••• 42 23. Sorting— phi standard deviation, San Diego ...•••.«••••••• 43 24. Histogram of sorting (phi standard deviation) •••••••••••••• 44 25. Median diameter vs. sorting ••••••• 46 26. Histogram of first phi skewness • • • • • 48 27. Pt. Arguello to Santa Barbara, first phi skewness ••••••••••••• 49 28. Santa Barbara to Point Dume, first phi skewness ••••••••••••• 50 29. Santa Monloa Bay, first phi skewness • . 51 30. First phi skewness, San Pedro......... 52 31. Newport to Mexico, first phi skewness • • 53 ix Figure Page 32. Flret phi skewness, San Diego • •••••• 54 33* Histogram of aeoond phi akewneaa........ 55 34* Pt. Arguello to Santa Barbara, aeoond phi skewneas •••••••••••••• 57 35. Santa Barbara to Point Dume, aeoond phi akewneaa • •••»•••»••••. 58 36. Santa Monica Bay, aeoond phi akewneaa . . . 59 37. Second phi akewneaa, San Pedro •••••• 60 38. Newport to Mexloo, second phi akewneaa • • 61 39. Second phi akewneaa, San Diego •••••• 62 40. Histogram of sand content................ 63 41. Pt. Arguello to Santa Barbara, sand content ••••••• 64 42. Santa Barbara to Point Dume, aand content • 65 43. Point Dume to Newport, aand content • . • • 66 44. Newport to Mexico, aand content •••••• 67 45. Histogram of silt content •••• 69 46. Pt. Arguello to Santa Barbara, silt content • ..... 70 47. Santa Barbara to Point Dume, silt content • 71 48. Point Dine to Newport, silt content • • • • 72 49. Newport to Mexloo, ailt content •••••• 75 50. Histogram of clay content ••••••••• 74 51. Pt. Arguello to Santa Barbara, clay content •••••••••••••••.. 76 Figure Page 52. Santa Barbara to Point Dume, olay oontent 77 53. Point Dume to Newport, olay oontent • • • 78 54. Newport to Mexloo, clay content • • • • • 79 65. Llthofaciea patterns • 85 56. Submarine topography of mainland shelf — Santa Barbara to Port Hueneme • . . . 90 57. Grain size and bottom topography, Santa Barbara Point to Santa Clara River • • • 97 58. Submarine topography, Santa Monloa Bay (after Terry, Keesllng, and TJohupl, 1956).......................... 100 59. Median diameter vs. water depth. Corona Del Mar to Carlsbad...... Ill 60. Locations of sampling profiles of the nearshore environment • .............. 119 61. Sediment size, Santa Monloa Bay, 1936-1956 123 62. Sediments of the near-oanyon areas • • • • 131 63. Average values of sediment grain size • • 135 64. Blook diagram, average size parameters • • 138 65. Sediment characteristics near headlands • 141 66. Sorting (phi standard deviation) vs. skewness ........................... 147 67. Skewness vs. sorting, Santa Barbara Shelf............................... 148 xi Figure Page 68. Sediment deposits of the mainland shelf • . 153 69. Genetic units............................. 158 TABLES Table Page 1. Sediment types of the mainland shelf • . • 22 2. Nitrogen content of sediment types present on the mainland shelf... 80 3. Average values of sediment parameters • . 150 4. Locations and major features of mainland shelf deposits................. 152 5* Classification of sediment origin .... 157 INTRODUCTION Kargins of continents extend seaward fro* shore an average of 40 miles as smooth surfaces dipping about one- tenth of a degree (Shepard* 1948). The submerged part of the continents that is nearly horizontal is the continental shelf, having as its seaward boundary the steeper continen tal slope averaging 4°. Seaward is the abyssal ooean. The continental shelf adjaoent to southern Cali fornia is different in form than the average. This northwest-trending dlamond-Bhaped area is about 150 miles wide and 600 mile.B long. It is characterized by many deep basinB and shallow banks whioh resemble the Basin and Bange geomorphio province of North America. The name Ncontinental borderland" was applied by Shepard and Baerj (1941) to distinguish this type of continental margin from the more typically smooth* gently Bloping surface. Average depth of the continental borderland is 3000 feet* muoh great er than average depth of the continental shelf. The basins and banks of the continental borderland are considered to be fault blocks (finery* I960). Between the submerged basln-and-bank region and shore is a long* narrow, generally smooth surface that* except for its narrowness* compares with the continental shelf of other North American coasts. This nearshore sur- face average0 4 miles in vidth and is named the mainland shelf. Seaward is a series of basins approximately 2400 feet deep* Topography The mainland shelf extends from Point Oonoeptlon southward to the vlelnity of Oedros Island, Baja Cali fornia, Mexico. The area investigated is that part of the mainland shelf north of the Mexican border. Vidth of the shelf is generally less than 7 miles, but 1b greater than 10 miles in Santa Monica Bay, south of San Pedro, south east of Santa Barbara, and west of San Diego. The floor of the mainland shelf is a nearly smooth slops from shore to a depth of about 300 feet. It is not featureless, but haB shallow depressions and terraoes at various levels (Bnery, 1958) and areas of mlcrorellef (Terry and StevenBon, 1957)• The bottom slope of the main land shelf is approximately 75 feet per mile from shore to depths of 300 feet, beyond which the floor dips 600 feet per mile. The discontinuity in bottom slope is the shelf l u a t i c . Ten major submarine canyons cut across the mainland shelf, segmenting it into units; some canyons extend to less than a mile from shore. Existence of these sub marine canyons excludes the possibility of vast longshore sediment transport on the mainland shelf. Coarse sediment settles into the oanyons and eventually moves seaward along canyon axes. Some sediment undoubtedly passes around can yon heads, but this is confined to the coarser beaoh material. Regional Geology The mainland shelf lies in the vicinity of the boundary between two major structural provinces of North America: the Transverse Range and the Peninsular Range. The overall arcuate trend of the mainland shelf results largely from structural change of east-west orientation near Point Conception to north-south near San Diego. On land, junction of the two is characterized by blook fault ing and a thick sequence of Hlocene to Pleistocene sedi ment in the Los Angeles and Ventura Basins. These basins are now filled to above sea level, except for Santa Monica and San Pedro Bays. In contrast with still-submerged bays offshore from the Los Angeles Plain, the region between Santa Monica Mountains and Santa Ynez Mountains (both headlands) not only has been filled, but deposition by the Santa Clara River has produoed a seaward bulge of sediments that has encroached nearly half way across the mainland shelf. This encroachment has restricted the general shape of the embayment between Santa Barbara and the Santa Monloa Mountains, but the area nevertheless remains one of four wide segments of the mainland shelf. Major rivers that carry sediments to the mainland shelf are the Ventura and Santa Olara Rivers, whloh drain Santa Inez Mountains and discharge into the Santa Barbara embayment; the Los Angeles and San Gabriel Rivers, whloh drain the southern slopes of the San Gabriel Mountains and discharge into the San Pedro embayment; the Santa Ana and Santa Margarita Rivers, which drain the westward slopes of the Santa Ana Mountains and discharge onto the shelf be tween Huntington Beach and La Jolla; and the Tla Juana River, which discharges onto the shelf south of San Diego. Other streams of lesser magnitude exist elsewhere along the coast but are usually dry. The shoreline adjacent to the mainland shelf con sists of rugged mountainous terrain alternating with smooth depo8ltional plains. Prom Point Conception to Ventura, the mountain slopes rise steeply from the sea. At Ventura the Oxnard Plain, 16 miles wide, borders the shoreline to Point Mugu, east of which the Santa Monica Mountains front the coast for 30 miles. The ooast grades Into the Los Angeles Plain, which faces Santa Monloa Bay for a distance of 20 miles and San Pedro Bay for 20 miles. Between the two bays the Intervening Palos Verdes Hills have 15 miles of coastline. Slopes of coastal parts of the Santa Ana Mountains and foothills face the mainland shelf for a distance of 95 miles, as far south as the border of Mexico. The total length of the mainland shelf Is approximately 280 miles. Previous Investigations Three parts of the mainland shelf have been Investi gated by previous workers. Santa Monica Bay was studied by Shepard and Macdonald (1938) and by Terry, Keesling, and Uohupl (1956). The flrBt report lnoluded analyses of 133 bottom sediment samples, and the second Included 380 bottom samples. These studies Indicated a general pro gression from sand nearshore to slit offshore. In parts of Santa Monica Bay this trend Is Interrupted by coarse material consisting of organic debris, authlgenlc minerals, and relict deposits which have remained exposed since the last rise of sea level. Pine sand and silts are now being deposited In nearshore regions of the bay. Major con stituents of sediments are quartz and feldspar, rock frag ments, shell fragments, glauconite, and phosphorite. Pre dominant sediment type is a fine-grained quarts-feldspar sand. There Is a tendency towards better sorting of sedi ments near the shelf-break and In the non-deposltional area on the central shelf. In this area are anomalous fragments of gravel and shell, authigenic minerals, and a micro- topography which is more pronounoed than elsewhere In Santa Monloa Bay. San Pedro Shelf was studied In detail by Moore (195^) and Stevenson, Conrey, and Gorsllne (1954). The oentral portion consists of outcropping Middle Mloosne shale, limestone, and sandstone. Unoonsolldated sediments blanket the remainder of the shelf and can be divided Into six types according to their texture and color. There is no correlation between grain size and distance from shore, or with water depth, except on the slope. Possible in fluence of shoreline configuration upon waves and currents has the greatest effeot on grain size. Sediment sorting appears to refleot Influence of currents and wave action, particularly at the eastern end of Los Angelas Harbor, which is unprotected from wave approach. The shelf off San Biego was described by Emery, Butcher, Gould, and Shepard (1952). South of Point Loma are outoropplng Oretaceous shales and sandstones that are partly covered by unoonsolldated sediment. Chief factors of sediment distribution on the shelf are earlier deposi tion at depths now below effective wave action and present deposition in areas adjoining beaches. Mineralogy of sediments 1b similar to mineralogy of Plioosne-Pleistocene rocks that are exposed on nearby land. Bottom materials on the shelf lnolude shell, rock, gravel, sand, and silt. The dominant sediment type is fine gray sand, but notable deposits of medium to coarse gray sand and medium to coarse brown sand ooour in the vicinity of the border of Mexloo. Median diameters west of Point Loma show a seaward grada tion of ooarse to fine, but south of Point Loma this relationship doeB not exist. Here sediment size is almost consistently in the fine to very fine sand range aoross the entire shelf. There have been several studies of smaller areas immediately adjacent to shore. Inman (1953) examined sedi ment distribution on a triangular-shaped platform between two branches of La Jolla Submarine Canyon. Because long shore movement of bottom material is Interrupted by canyons, any sediment on the inter-oanyon shelf comes from movement around canyon heads and outward from the beach. The inter- canyon shelf slopeB seaward to a depth of 200 feet. Inman concluded that type of environment, such as beach, surf, or shelf, exerts greater Influence on sediment pattern than does seasonal change, because the sediment pattern remained consistent throughout a year. Contours of sediment pro perties align parallel to shore, which Inman believed ex cluded rip currents as major depositlonal agents. Sedi ments on the inter-canyon shelf are coarser in general than sediments at comparable depths from nearby areas. This suggests that longshore transport Is an important deposi- tional process In the absence of barriers* such as canyons, Wlmberley (1955) studied the region north of La Jolla Canyon, There was a general gradation from coarse to fine material with distance from shore* and a variation of sediment properties corresponding to depth. Throughout this area* sediment characteristics correlate with depth of water. In one part* where the bottom from 30 to 60 fathoms slopes gently seaward* an abundance of rounded rock fragments* ooarser than 2 mm* suggests abrasive aotlon of shallow waves during a lower stand of the sea. Purpose of This Study Detailed knowledge of the previously-mentioned areas of the mainland shelf existed* but the intervening parts were not well known. The existing knowledge was obtained through various techniques* such as visual determination of sediment properties in some areas* measurement In others; variation in sample spacing; and different types of sampl ing equipment. All sediment size parameters were not com puted for all areas, and sample data were obtained with non-uniform techniques. It seemed desirable to tie together knowledge of the areas whloh had already been studied and to obtain com parable data for the entire mainland Bhelf on the basis of a relatively uniform sampling pattern, uniform analysis techniques, and Identical sediment parameters. Of the previously-mentioned works, for example, only the papers by Inman and Moore Included maps of sediment skewness or phi standard deviation. Detailed maps of mainland shelf sediments were desired, but obtaining them required not only shipboard collection of new samples from the un studied areas but also from the known areas under uniform conditions. Then with comparable data from all areas, examination and evaluation of the mainland shelf from the standpoint of varying environmental conditions might begin. This might lead to determination of present deposltlonal areas and areas of older unconsolidated sediments of former environmental conditions. Attempting to explain the present distribution of unconsolidated sediments on the sea floor in terms of present sedimentary processes is useless if one cannot distinguish between modern and older deposits. Acknowledgments Appreciation is extended to Dr. K. 0. Query (Chair man), Dr. Orville L. Bandy, Dr. Richard Merrlam, Dr. John W. Reith, and Dr. Rlohard 0. Stone, members of the disser tation committee* Dr. Robert E. Stevenson and Dr. Robert L. Folk read an early manusoript and supplied helpful sug gestions. Disoussiona with fellow students and eolleagues Miss Johanna Resig, Dr. Vlllis Pratt, and Dr. Blasar TJohupl contributed to development of ideas for this study. Mr* 10 William Mersells assisted with laboratory analyses* Staff members of the Ulan Hanoook Foundation and crew members of the R/V Yelero IV provided many weeks of sample-taking at sea* Collection of samples was sponsored by the Cali fornia State Water Pollution Control Board as part of an oceanographic study off southern California* The Computer Center of the University of Puerto Rico (Mayagues) facilitated this researoh by developing computer program ming and by processing great quantities of sedimentary data* FIELD AND LABORATORY PROCEDURES Field Collection Sediment samples of the mainland shelf were taken from aboard Researoh Vessel Yelero IV of the University of Southern California. The sampling instrument was a large "orange-peel" dredge having a sampling area of about 2$ square feet (Durham, 1955). This sampler penetrates 6 to 30 lnohes into the bottom sediment. Most of each sample was screened aboard ship to separate sediment from bio logical specimens, but prior to screening one pint of sedi ment was removed and placed in a storage container. At that time a field description of sediment texture and color was made. Laboratory Analysis Several months or years elapsed before most of the sediments could be analyzed in the laboratory. During this time the samples dried and color ohanged. Interpretations of physical properties of mainland shelf sediments are based upon laboratory analyses of 643 bottom samples collected between 1957 and I960. They are distributed throughout the shelf with a spacing interval of approximately 1 mile (Figs. 1-5)* Each sample was soaked in water to disaggregate it and then wet-soreened through a 30' 40' » r • o ' x tM T iiH M t l STATE PROJECT SAMPLES PT. ARGUELLO TO SANTA BARBARA SAM PLE LOCATIONS Figure 1 •STATE PROJECT SAMPLES S A N T A B A R B A R A T O P O IN T D U M E S A M P LE L O C A T IO N S F ig u re 2 •S T A T E PROJECT SAMPLES EARLIER SAMPLES POINT DUME TO NEWPORT SAMPLE LOCATIONS Figure 3 NEWPORT TO LA JOLLA S A M P L E L O C A T IO N S Figure 4 16 117 15 r.-SE \ * * • P o O O o o O lC G O ^oo» tfi USA, o oo °° r 8 • I f 0° ° 8 ° « ° o ° o 0 STATE PROJECT SAMPLES O EABLICP samples DREOCE LINE Figure 5 SAMPLE LOCATIONS ITAntTI MU I S--'1Q0 root COMTOU* LA JOLLA TO MEXICO 25' 117* 15' sieve with openings of 0.062 mm, This procedure separated the "coarse fraction" from the "fine fraotlon." Fine material from each sample was retained in a one-liter cylinder, washed, and filtered several times to remove salts. The coarse fraction was weighed. Including a separate weighing of all particles larger than 2 am (gravel fraction). The two fractions (coarse and fine) were analysed separately using standard procedures (Allan Han- cook Foundation, 1958)* Analyses of both fractions are based upon known settling velocities of particulate matter through water (Krumbeln and PettiJohn, 1938). The technique oonslsts of collecting sediment fractions that have settled through a known length of water oolumn for a known period of time. Coarser particles will settle faster. In analysis of the coarse fraction, recordings are made of volume of sample that colleots at bottom of the settling tube (Smery, 1938). In analysis of the fine fraction (pipette method), record ings are made of weight of material remaining in suspension after known time intervals, the differences between suc cessive recordings indicating the amount of material of known size that has settled to the bottom (Krumbeln and Petti John, 1938). Results of analyses of the two sediment fraotlons (sand - coarser than 0.062 mm, and mud - finer than 0.062 mm) are combined mathematically In a single cumulative grain size frequency distribution curve, plotted 18 on probability graph paper. Prom size percentilea numer ous sedimentary parameters (Krumbeln and Pettijohn, 1938, and Inman, 1932) were oomputed to desorlbe various size characteristics of each sample* Is an additional aid to visualizing the regional sedimentary variations, a representative part of eaoh coarse fraetlon was transferred to a small container and plaoed over Its geographlo location on a large map of the mainland shelf* This sediment map revealed many natural groupings of sediment characteristics (for example, con centrations of mica, shell, or gray sand). Knowledge from this visual sediment map then aided examination of ooarse fractions under a binocular microscope and classification aceordlng to composition* In the final stages of this research, two programs for an IBM 1620 computer were developed to check data for 645 samples analyzed for this work and to determine com parable data of 744 samples from earlier surveys* Data of these 1389 samples as well ae reports of other workers are used in this research. PROPERTIES 0? THE SEDIMENTS Sediment Texture Sediment Tree Unconsolidated sediments off southern California consist of Individual grains that range In diameter from several millimeters to Issb than 1 micron. For conven ience In sediment descriptions, the Wentworth nomenclature of else classification (Wentworth, 1922) has been ac cepted. Two major units of this classification are sand, which Includes all particles having intermediate diameters between 2.0 mm and 0.062 mm, and silt, having Intermediate diameters between 0.062 am and 0.004 mm. Larger partloles are grouped as gravel (having Intermediate diameters greater than 2.0 mm), and smaller particles are grouped as clay (having Intermediate diameters less than 0.004 mm). 1 sediment sample contains various percentages of some, or all, of the groupings of gravel, sand, silt, and clay. ▲ triangular size-composltion diagram (Fig. 6) may be used for classification of sediment types (Terry, al, 1956). This diagram represents one faoe of a tetrahedron, the four corners of which represent 100 per cent gravel, sand, silt, or clay. Because the gravel constituent is rare on the mainland shelf (only 7 per cent of the analysed samples contained gravel), particles greater than 2.0 am 20 SAND 8 GRAVEL 100 % 80 33 SILTY CLAY CLAYEY SILT SILT 100 % CLAY SILT * PATTERNS DENOTE FREQUENCY OF OCCURRENCE PER 5% COMPOSITIONAL TRtAMgLE 1 -2% >2% ^os-1% (nflai-As* CLASSIFICATION OF SEDIMENT TYPES Figure 6 21 In diameter were grouped with sand to font a three com ponent eye ten. It should be remembered, therefore, that •'sand," as used in conneotlon with the triangular diagram, refers to sand and gravel. The triangular sediment classification is divided into 12 sediment types according to the percentage com position of the three size groups (Fig. 6). Divisions are assigned descriptive names, Buch as sandy silt and silty sand. A sample haB only one possible position within the triangular diagram. Onoe the size composition is known, sediment type is readily determined. Samples from the mainland shelf constitute a con tinuous series varying from 100 per cent Band to 100 per cent silt (Fig. 6). Most of the samples contain less than 10 per cent clay size particles. Of the total number of analyzed samples, 27 per cent are sand, 25 per cent are silty sand (that is, they contain between 50 per cent and 80 per cent sand), 25 per cent are sandy silt (50 per oent to 80 per cent silt), and 14 per oent are silt. A concen tration of points in the sand group exists because a relatively large number of samples were obtained from near shore (less than 50 feet of water). The triangular diagram shows that the average sediment of the mainland shelf con tains almost equal quantities of sand and silt grains and lesB than 10 per oent clay grains. In other words, the typical shelf sediment is at the boundary between sandy 22 Bilt and silty sand. 1 small number (11 per cent) of the samples had more than 10 per cent clay. These samples fall into three sediment groups (in the order of increasing abundanoe): olayey silt, olayey sandy silt, and clayey silty sand* For convenience in this report, these three sediment types are referred to as "olayey sediments," a term signifying at least 10 per cent clay content. Distribution of sediment types on the mainland shelf is shown in Figures 7-10 and in Table 1. Areal coverage of each of the five major sediment types is as follows: Almost all olayey sediments are oonoentrated in the vicinity of the olties of Santa Barbara and Ysntura (Fig. 8). Much of the sand is concentrated in the nearshore environment, but there is sand at all water depths, Sedl- TABLE 1 Sediment Types of the Mainland Shelf Sand 22 per cent 30 per oent 24 per oent 16 per cent 8 per oent 100 per oent Silty sand Sandy silt Silt Clayey sediments Total *rxs- ]yO y'& 0 ; * ; , J but* I'•>:-1 CUHCV *LTy 1«MD ViVi umot w t r vvs V •X C U t t Y S A H P Y *tt • o ’ * • * > «-T 3Cf X T D * 0 0 * 0 0 * s c r C U V C f » L T iTAran M n PT. ARGUELLO TO SANTA BARBARA S E O IM E N T T Y P E S Figure 7 VCNTUU S A N T A B A R B A R A TO P O IN T D U M E SEDIMENT TYPES Figure 8 V POINT DUME TO NEWPORT SE D IM E N T T Y P E S Figure 9 (0 cn NEWPORT TO MEXICO SEO m iN T TYPES Figure 10 ( O o> 27 sent distribution Is patchy, so that not everywhere Is there a simple seaward progression, nor a relationship to depth of water. The shelf deposits do not oonslst en tirely of modem detrital materials that are oarried from land by streams and distributed throughout by waves and currents. Many other factors besides ware action of pre sent sea level influenced sediment on the mainland shelf. Another classification of sediments according to their size characteristics can be made by median grain diameter. Measurement of medians supplies a numerical ByBtem that shows in greater detail relative variation in sediment size. Each of the fundamental sediment groups (gravel, sand, Bilt, and day) is subdivided into frac tions, designated coarse, medium, fine, and very fine (Wentworth, 1922). Median diameter may be used to classify each sample. Use of medians has oertain dis advantages that must be kept in mind. Por example, if a sediment consists of materials from two different sources having different size characteristics, median diameter may indicate a grain size that is present in only small amounts. This parameter does not always adequately des cribe sediment size. Of the 645 bottom samples uniformly analyzed for this study, median diameters ranged from 0.00$ am to 0.625 am* The histogram of median diameters on the mainland shelf (Fig* 11) shows that very fine sand (0*125 mm to 0*062 mm) Is the most abundant sediment size (37 per oent of all samples), but that ooarse silt (0.062 am to 0*031 mm) is almost equal In abundance (35 per oent)* The average median diameter for the shelf Is 0*060 am* Median dlameterB larger than very fine Band (0*125 mm) and smaller than ooarse silt (0*031 mm) total only 27 per oent of all samples analyzed* Beoause these samples have a reasonably equal distribution throughout the region, the figures may be accepted as typical of the sediment characteristics of the mainland Bhelf* Areal distribution of median diameters Is shown In Figures 12-17* Sediments with smallest median diameters, averaging 0*041 mm, are. concentrated on the central part of the shelf between the cities of Santa Barbara and Ventura (Fig* 13)* Ooarse sediments occur throughout the shelf in numerous patches, but are most abundant on the wide shelf near San Diego (Fig* 17)* where the average Is 0*107 mm* In many places there Is a trend from fine and very fine sand near shore to coarse Blit farther seaward* Such a trend probably Indicates deposition of modem detrital sediments under present environmental conditions* Where contours of median diameter are not parallel to the present shoreline, or where they are parallel but the sediments become coarser with distanoe from shore, another 29 < /) UJ < i/i < ¥ ~ O UJ o <r UJ 0. 35 30 25 20 15 10 — VERY — f in e COARSE — SAND SILT — FINE _ _ SAND >0.500 MEDIUM SANO MEOIUM SILT FINE SILT <0.006 0.500 0.2500.125 Q062 Q03I 0.016 0.008 M E D IA N D I A M E T E R ( M M ) HISTOGRAM OF MEDIAN DIAMETERS Figure 11 4 c r 40* OMOTA PT. ARGUELLO TO SANTA BARBARA MEDIAN DIAMETERS CONTOURS IN MM Figure 12 u o / / itiTm M l SANTA BARBARA TO POINT DUKE MEDIAN DIAMETERS CONTOURS IN NM Figure 15 OS H Figure 14 S A N T A M O N I C A BAY ftODUN DIAMETER (MM) •*>« 500 f t DEPTH CONTOUR o - w c* to Figure 15 SAN PEDRO M E D IA N D IA M E T E R (MM) S A N P E D R O — FT DEPTH CONTOUR 01 01 V NEWPORT TO MEXICO MEDIAN DIAMETERS Figure 16 36 « > o o n Q ) \ 0 - 300 FT DEPTH C O N TO U R Figure 17 explanation for their occurrence must he sought 36 Sorting ill of the various methods of oomputing sediment sorting are designed to indicate the degree of grain size uniformity within a sample. Sediment that consists only of sand grains frequently is well sorted but may be poorly sorted if nearly equal amounts of coarse, medium, fine, and very fine sand are present. On the other hand, sandy silt may be well sorted if most of the grains have diameters that approximate 0.062 mm. Other samples of sandy silt may, of course, be poorly sorted. 1 measure of sorting is the phi standard deviation. The phi soale (Krumbein, 1934) is a mathematical devloe that permits application of statistical procedures to sedimentary data. Grain diameter (d) in millimeters is oonverted to phl-unlts by the relationship: phi = -log2 d. Various sedimentary parameters, analogous to the moment measures of statistics, can be expressed. One of these, phi standard deviation, is a measure of sorting whleh indicates the number of phi-units (MoManus, 1963) within whloh 67 per cent of the grain size frequenoy distribution is included. Samples with standard deviation values of 0.00 phl-units are perfeotly sorted (that is, all grains are of the same size— an impossibility in natural sedi ments). Samples with high values are more poorly sorted than those with low values. In Pigures 16-23 the geo graphic distribution of phi standard deviation ranges from 0.23 to 3*48 phi-units. The average for the mainland shelf is 1.00 phl-unlts (based on samples having uniform geographic distribution throughout the area). Xmery (195*), in a study of average sediment parameters for various environments inoluding mainland shelves, points out that the degree of sorting (well sorted, moderately sorted, and poorly sorted) is meaningful only within a restricted geographlo area and that numerloal classifica tions cannot have worldwide application. Boundaries in phi-units between well sorted sediment (0.50 or less), moderately sorted (0.50 to 1.00), poorly sorted (1.00 to 2.00), and very poorly sorted (more than 2.00) have been arbitrarily ohosen after studying natural groupings and the total range of sorting variation on the mainland shelf (Pig. 24). There is some tendency for sediments with medians about 0.062 mm to have the best sorting (Pig. 25). Samples with medians progressively finer than 0.062 mm are more poorly sorted, but the trend is less definite for samples with medians ooarser than 0.062 mm. Skewness In "normal" sediment else distribution, median diameter oiincldes with sample mean. Departures between •a PT. 100- o o - « r PT. ARGUELLO TO SANTA BARBARA SORTING - PHI STANDARD DEVIATION Plgure 18 oi © I V SANTA BARBARA TO POINT DUME SORTING - PHI STANDARD OEVIATION Figure 19 w to Figure 20 KCOWOO F i g u r e 2 1 50' 20' 1 0 ' c o Ui o tc Zui 4 > 1 1 0 * r S O R T IN G 50 UJ § * P H I S T A N D A R D D E V IA T IO N S A N P E D R O 4 C O N T O U R 4 6 33* 40' s t a t u t e M I L C S PEDRO 33* 40' 30' 0.00 -0.50 0.90- 1.00 1.00-2.00 2.00-4.00 2 0 ' WELL SORTEO MODERATELY SORTEO POORLY SORTEO VERY POORLY SORTEO ____________________I _____ 1 0 ' S a. * u i co us* 30' NEWPORT TO MEXICO SORTING - PHI STMOARO DEVIATION Figure 22 43 SAN DIEGO C D 4 C - - ¥} POMT LOMA V \ Figure 23 PERCENT OF TOTAL SAMPLES 301 — 44 25 20 15 10 W E L L iORTED _L AVERAGE SORTING I POORLY SORTED I VERY POORLY S O R T E D « > 0.25 0.50 0.75 1.00 L50 2.00 2.50 3.00 PHI STANDARD DEVIATION (SORTING) HISTOGRAM O F SORTING (PHI STANDARD DEVIATION) 3.50 Figure 24 Flguro 26 FREQUENCY OF OCCURRENCE PER UNIT AREA >3% 23-3% K 2 00 15-2.3% 3 03-13% 0.1-0.8% UNIT AREAs Q 0 o 0.290 0.062 0 . 1 2 9 DIAMETER IN MM 0.008 0004 MEDIAN DIAMETER vs. SORTING O t 46 mean and median are measured by phi skewness. Skewness indicates presence of small aaonnts of partlolee at the size extremities. These particles are not sufficiently abundant to influence the position of Median diameter. Thus if a small surplus of fine sediment, say 10 per cent, was added to a sample with a nearly noxmal size frequency distribution* the Burplus does not appreciably alter the median, but results in a skewed size ourre. This measure ment is of value to show multiple sources of sediments in oertaln areas. Theoretically skewness la Independent of the average grain size of a sample. Skewness is measured by many methods. Those used in this report are first phi skewness* computed from the 16th and 84th percentiles of the cumulative size frequenoy curve, and second phi skewness, computed from the 5th and 95th percentiles. Seoond phi skewness lndloates a surplus of small amounts of sediment; first phi skewness* a larger surplus. Samples with skewness values close to zero most nearly resemble normal sediment distribution. Those with negative values have an additional quantity of material added at the coarser end of the sizes present; those with positive skewness values have a surplus of material on the finer end of the curve. Arbitrary boundaries to skewness classes must be used in order to classify mainland shelf sediments. These limits wert chosen by observation and general usefulness. 47 For first phi skewness the boundary between weakly and strongly positive skewness (both having a surplus of fine ■aterlal) Is taken at the value of 0.40 (Tig. 26). Vo distinction Is Bade between weakly and strongly negative skewness, beeause relatively few samples have large nega tive values. Most samples from the mainland shelf have weakly positive skewness (0.00 to 0.40), which indicates a slight surplus of fine material. A large part (27 per oent) of shelf Bamples have strongly positive skewness. Abundance of Bkewed sediments suggests multiple origins, only one of which Is marine deposition of detritus from terrestrial regions under present environmental conditions. Others may t be organic origin In the form of shell fragments or beach origin when sea level was lower. Areal distribution of first phi skewness on the mainland shelf is shown in Figures 27-32. Second phi skewness, which measures distribution of sediment grains between the 5th and 95th peroentiles of the cumulative else frequency curve, has a similar concentra tion of positive values (Fig. 33). Only 20 per cent of the mainland shelf samples have negative seoond phi skewness values. Of the positive values. 50 per cent of all samples are strongly positively skewed (values more than 0.90). and 33 per oent are weakly positively skewed (0.00 to 0.90). A predominance of positive values indicates that small PERCENT OF TOTAL SAMPLES 46 25 20 15 10 NEGATIVE ± I I W E A K L Y POSITIVE I I S T R O N G L Y POSITIVE -0.60 -0.40 -0.20 0 0.20 0.40 FIRST PHI SKEWNESS 0.60 HISTOGRAM O F F IR S T PHI SKEW NESS Figure 26 JO' 9 t f OMOTA *Cf s c r PT . ARGUELLO TO SANTA BARBARA F IR S T P H I SK EW N ESS Figure 27 SANTA BARBARA TO POINT DUME FIRST PHI SKEWNESS Figure 28 o Figure 29 3V «»ST PHI SKEWNESS - - 300 f T OtPTN CONTOUR E <000 NCQATIVC r 00-040 «CttLY ROttTNt >0 40 STNOMLT POtlTIVf - S O - SO 2 V * 0 Figure 30 5 0 ' 20’ “T 50’ FIRST PHI SKEWNESS SAN PEDRO |T| < 0.00 NEGATIVE (T| 0.00 • 0.40 WEAKLY POSITIVE POSITIVE 3 3 * 40‘ SAN PEDRO & — F T D EPTH 0 2 CONTOUR * e V t l u ’ t M i t t s FIR ST PHI S K E M E S S Figur* 31 s L. 64 4 5 * SAN OICGO 4C - PONT LOUA Figure 52 PERCENT O F TO TA L SAMPLES 56 30 25 20 15 10 I NEGATIVE I <-0.45 I W EA KLY PO SITIV E S T R O N G L Y POSITIVE _L I I >4 00 J_____ -0.45 0 0.45 0.90 200 300 400 SECOND PHI SKEWNESS HISTOGRAM OF SECOND PHI S K E W N E S S Figure 33 56 quantities of fine-grained material are being added to an otherwise normal sediment distribution* This surplus of fine material probably reflects slow adjustment of shelf sediments to present environmental conditions. Areal dis tribution of second phi skewness is shown in Figures 34-39. 8and Content Sand content of the sediments ranges (Fig. 40) rather uniformly from 10 per oent to 90 per oent* Greater abundance of samples with sand oontents from 90 per oent to 100 per oent results from the many shallow water samples* A similar number of samples with low sand content results from the concentration of samples on the shelf near Banta Barbara* where medians are in the silt range. Aside from these two somewhat anomalous concentra tions* an even distribution of sand exists on the shelf as a whole (Fig* 40)* In other words* samples with sand oontents between 10 per oent and 20 per cent are about as abundant as those between 20 per oent and 30 per oent or between 30 per cent and 40 per cent* etc* The areal dis tribution of Band oontent on the mainland shelf is shown in Figures 41-44. w * 1 PT AMUELLO QMOTA :■ m PT. ARGUELLO TO SANTA BARBARA SECOND P H I SKEW NESS Figur* 54 (n I I ! 1 i (w < * \ SANTA BARBARA TO POINT DOME SECOND PHI SKEWNESS Figure 35 o i CD Figure 36 ft W- * C ---------- ft NIC A BAY SKEWNESS ■ I f OCPTW CONTOUR K M T lV t W IMLV FOOTWV s t r o n r l t Rotmvc - W ■ir cn (D 20' 118 ' 50' 50' m S E C O N D P H I S K E W N E S S S A N P E D R O oce 5? LU <0.00 NEGATIVE |T) 0.00*0.90 WEAKLY POSITIVE m >0.90 STRONQLY POSITIVE SAN PEDRO 33* 40' w F T OEPTM C O N T O U R 30' 30' 20' MB* V NEWPORT TO MEXICO SECONO PHI SKEWNESS Figure 58 62 DIEGO 0 5 0 .a.?— W E * ' C O SECOND PHI SKEWNESS SAN DIEGO COHONAOOS 1 I SLAWS I D < 000 negative ISOOO-090 WEAKLY POSITIVE (S »0M strongly positive 500 f T . depth CONTOuh Figure 39 0 D 20 30 40 SO GO 70 60 PERCENT SAND CONTENT HISTOGRAM OF SAND CONTENT F ig u re 40 rs« . 75* *0 * 4 o r ............... tttTVtl Mbtt PT. ARGUELLO TO SANTA BARBARA SAND CONTENT CONTOURS IN PERCENT OF TOTAL SAMPLE Figure 41 2 t ___ g ___ r « ___ i m i SANTA BARBARA TO POINT DUKE SAND CONTENT CONTOURS IN PERCENT OF TOTAL SANPLE Figure 42 o» 01 V POINT DUME TO NEWPORT SAND CONTENT CONTOURS M PERCENT OF TOTAL SAMPLE Figure 43 01 Ok NEWPORT TO MEXICO SANO CONTENT c w w mu a m c t a r or toth. m Figure 44 o> -4 68 §11£ Ognjeiit About one-fifth of mainland shelf samples have silt contents (0.062 am to 0.004 am) between aero and 10 per oent (Pig. 45). These are mostly sands from the nearshore regions and a coarse to medium red sand found mostly in the Tlclnlty of San Diego. Using 10 per oent silt content intervale, sample abundance varies from 7 per oent of the total samples to 12 per oent. Generally the per oent dis tribution for eaoh 10 per oent silt interval is uniform up to values of 90 per cent. Only 2 per oent of the samples oontalned 90 per cent to 100 per cent silt. Areal dis tribution of silt content on the mainland shelf is shown in Figures 46-49. Olav Content The per cent Baaple distribution of olay content (Pig. 50) differs from silt and sand distributions in that equal per cent classes do not occur in approximately equal abundance throughout the shelf. More than 36 per cent of the samples analysed had olay contents less than 2 per cent. These are mostly beach and coarse reliot sediments where no fine material is now being deposited. For samples trtth olay oontents less than 10 per oent there is a de crease in percentage of sediment samples corresponding to an increase in olay content. Probably this indloates that PERCENT O F TO TA L SAMPLES 69 22— 20— 18— 16— 14 — 12 — 1 0 — 6— 4 — 2— ------------ 0 (O 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 100 PERCENT SILT CONTENT H ISTOGRAM O F S I L T C O N T E N T F ig u re 46 •o r »Mtf OMOTA s c r P T . ARGUELLO TO SANTA BARBARA S IL T CO N TEN T CONTOURS IN PERCENT OF TOTAL SAMPLE Figure 46 o iwvn «ui SANTA BARBARA TO POINT DUME S IL T CONTENT CONTOURS IN PERCENT O f TOTAL SAMPLE Figure 47 M A i«*»n M l POINT DUME TO NEWPORT SILT CONTENT CONTOURS IN PERCENT OF TOTAL SAMPLE Figure 48 NEW PORT TO MEXICO SILT CONTENT CMTMM MKKUT or tSMt. M M Figure 49 -a w PERCENT O F TO TA L SAMPLES 40— , 36-” 32- - 28- 24- 20- 16- 12 - >16 8 1 0 1 2 1 4 l < PERCENT CLAY CONTENT HISTOGRAM O F CLAY C O N T E N T Figure 50 75 olay 1* not a normal sediment constituent on the mainland shelf, and its occurrence In a few locations la atyploal. In oontraat to sand and silt contents, which range from aero to nearly 100 per cent, most olay contents are less than 16 per oent, and none Is greater than 52 per cent, ▲real distribution of olay oontent on the mainland shelf Is shown In Figures 51-5^• Gravel Oontent Only 7 per cent of samples from the mainland shelf contained grains larger than 2,0 mm. Of these, about one- half had less than 5 per cent gravel. Percentages within succeeding 5 per cent Intervals drop to progressively lower values. Maximum gravel content of these samples Is 29 per cent. The progressive gravel deorease indicates that gravel, as well as olay, Is not a typical sediment constituent on the mainland shelf. Chemical Properties Organic Matter and Nitrogen Oontent Oontent of organic matter in more than 500 samples from the mainland shelf was reported by Uchupi (1961a) to be minor. Sources are terrestrial-vla-rlvers, sewage, and phytoplankton. Only a small percentage of organlo matter escapes destruction in falling through the water column, so* M n. ;uo \ OMOTA « a r «r PT . ARGUELLO TO SANTA BARBARA CLA Y CO N TEN T CONTOURS IN PERCENT OF TOTAL SAMPLE Figure 51 •4 0> S A N T A B A R B A R A TO P O IN T D U M E CLAY CONTENT CONTOURS IN PERCENT OF TOTAL SAMPLE Figure 52 3 A itun nit POINT DUM E TO NEW PO RT CLAY CONTENT CONTOURS IN PERCENT OF TOTAL SAMPLE Figure 55 NEWPORT TO NEXICO CLAY CONTENT Figure 54 -a «o 80 and auoh of that which roaches bottom la later rejuvenated by bacterial action* Nitrogen oontent of sediments is directly related to content of organic matter by a ratio of 1:17; hence» nitrogen oontent may be used as an indicator of both (Uohupi, 1981a). Nitrogen oontent in general Increases as grain else decreases, as indicated by the following table (after Uchupl, 1961a): TABLE 2 Nitrogen Oontent of Sediment Types Present on the Mainland Shelf Sediment Tree Average Nitrogen Oontent Sand *017% (160 samples) Silty Sand .040* (135 samples) Sandy Silt .041* (116 samples) Silt .056* ( 76 samples) Olayey Silty Sand *082* ( 5 samples) Clayey Silt .092* ( 16 samples) Olayey Sandy Silt *094* ( 13 samples) Silty Olay .120* ( 2 samples) This correlation with grain else is partly due to organic debris having low settling velocities that are comparable to finer grained sediments. Smaller pore spaces of fine sediments may inhibit water circulation and 81 retard decomposition of organic matter* although thie le not certain. Low values oloee to shore* on topographio highs* and in areas of low detrital sedimentation indicate rapid decomposition of organic debris. In contrast* areas relatively high in organic matter (such as off the mouth of Santa Olara Elver) indicate rapid burial before de composition and therefore a higher sedimentation rate. Hitrogen content in mid-shelf depths is greater (more than .05 per oent) than near the shelf-break or near shore (less than .05 per oent) on Point Oonoeption Shelf and in Santa Monica Bay. Near Santa Barbara* the pattern of nitrogen oontent is complex* following the textural pattern. San Pedro Shelf and San Diego Shelf are markedly low in nitrogen oontent (less than .05 per cent). Emery* e£ «!• (1952) found no organio matter in a beaoh sample and values from 0 to 1 per cent along a profile across the shelf near the Tia Juana River. The shelf from Newport to San Diego is low near shore and increases to values greater than .05 per oent at the shelf-breek. High nitrogen con tent (greater than .10 per oent) was found off White's Point* in the vioinlty of Los Angeles County sewage out fall. Organio matter and nitrogen oontent of sediments on the mainland shelf are thus partly man-oontrolled but mostly are the result of the rate of sediment deposition. Where deposition is slow* these constituents are small beoause 82 the/ are destroyed on the eea floor before burial. Calcium Carbonate QgJLteltf Benthonlo foramlniferal tests, larger shelled animals (such as bryozoa and gastropods) and caloareous algal fragments constitute a minor part of the mainland shelf samples. Chemically precipitated carbonate has not been found off southern California. Uchupi (1961a), reporting the results of more than 500 determinations from the mainland shelf, found that calcium carbonate oontent rarely exceeds 5 per oent, ex cept for shell concentrations near Port Arguello (17 per oent), in Santa Monica Bay (16 per cent), off Palos Verdes Hills (20 per cent), and near Point La Jolla (16 per cent). Beery, fit f c i . . , (1952) found similarly loir values near shore (less than 5 per oent) off San Biego and values between 5 per cent and 10 per cent at mid-shelf depths. Close to shore off Point Loma, oaloium carbonate Is about 25 per oent. In the oenter of Santa Monica Bay (Terry, al.. 1956) oaloium carbonate content is high but decreases shoreward to a general value of 5 per oent for most of the shelf. Strong ourrents and bottom turbulenoe keep these areas of high oaloium oarbonate oontent owept dean of finer terrigenous material, bmt allow accumulation of 83 larger inrertebrate shell fragments. Samples from the remainder of the mainland shelf have low oaloium carbonate oontent and large sample-to-sample variation that shove no reoognlsable trend. MAINLAND SHELF SEDIMENTARY UNITS A consideration of sediment properties» their relations to bottom topography, their geographical extent, color, type of shelf on whloh they ocoor, and other factors have resulted in the development of a lithofacies pattern on the mainland shelf (Fig. 55)* A discussion of these units, their properties, areal extent, and possible source areas is presented in the following sections. Point Conception Narrow-shelf Complex From Point Arguello to Santa Barbara Point the shelf is relatively narrow, averaging 4 miles, and extends 50 miles adjaoent to Santa Ynez Mountains* The trends of the mountains and the shelf are east-west, with Point Con ception protruding southwestward as a prominent physio graphic feature. This shelf is characterized by a complex textural pattern. Bottom materials are highly variable in size, distributed in patches, and a general progression of coarse sediment near shore to fine sediment offshore ooours in only a few places* Between Point Arguello and Point Conception, sedi ment type is mostly sandy silt (Fig. 7), but a progression outward from very fine sand to silt (Fig* 12) is revealed 86 rt m mu v / LITHOFACIES PATTERNS J H , Figure 55 by median diameters. Samples closer to shore are better sorted (0*00 to 0.50 phi-units) than those in deeper water (Tig. 18). First phi skewness values (Fig. 27) are weakly positive and seoond phi skewness values (Fig. 34) are strongly positive. Both sediment parameters lndioate the presence of a surplus of fine sediments, but in small quantities. The area between the two points of land re flects the influence of efficient wave action that oaused most of the fine material in suspension to be deposited far from shore. The surplus of fine grains, as shown by Bkewnese, means that distribution of sediments does not quite keep paoe with sediment supply. Between Point Conception and Gavlota, a blanket of fesnd and Bilty sand (Fig. 7) covers the shelf to a water depth of 300 feet. Nearest the point is very fine sand, and farther to the east fine sand is present. A . progres sion of ooarse to fine sediments with lnoreaslng distance from shore is lacking. Samples nearest the projeoting point of land are moderately sorted (0.50 to 1.00 phl- units), but to the east they are well sorted (0.00 to 0.50 phi-units), as shown by Figure 18. Skewness values are similar to those of the Point Arguello-to-Point Oonoeptlon region (Figs. 27 and 34), again indicating that small quantities of fine material have been added, probably reoently, to the shelf from land. Ooourrenoe of sand at all water depths to 300 feet just east of Point Oonoeptlon 87 Is probably the result of ware refraction around the point. ThiB concentration of wave energy prevents deposition of nodern detrital Materials, resulting in relatively ooarse sediment (fine sand). ?roB Gavlota to Goleta sediment distribution is quite different. Sediment types are silty sands and sandy silts (Fig. 7)» but no trend of ooarse to fine with dis tance from shore occurs, nor Is there a consistent sedi ment type. Median diameters (Fig. 12) are in coarse silt to very fine sand sizes, but the areal distribution is ir regular and complex. Part of this area shows a reversal of the usual trend, for fine sediments lie closer to shore than coarse materials. Deposits over the entire region are poorly sorted (Fig. 18). Values are greater than 1.00 phi-units and indicate lack of efficient wave sorting action. Both first and second phi skewness values (Figs. 27 and 34) are strongly positive, suggesting greater proximity to a source of fine sediment than the adjacent regions to the west. Sonoprobe profiles, which reoord sediment thickness and underlying bedrook structure by means of an acoustlo- reflection device, have been made by the United States Navy in the offshore region of southern California (Moore, I960). A sonoprobe profile off Goleta Point shows bedrook consisting of an east-west trending, truncated antlollne with its axis about two-thirds the shelf width from shore. In his dlsousslon* Moore eald a sediment cover less than 3 feet thick is not detectable on the records* whioh glree an indication that the sediment oover is thin. Between Gariota and Goleta* the shelf has not reoelTed an appreoi- able amount of modem detrital material* and the sediment pattern Is influenced by underlying bedrock, is sea level rose across the shelf It loosened and reworked debris from outcropping rock* distributing the fragments over the newly submerged surface. Present wave action has not Influenced these Bedlments enough to produce a seaward progression of coarse to fine fragments. The absence of a sedimentary cover of modem detrital materials from land areas is attributed to the rarity of streams and* con sequently* a lack of sediment supply. Eastvcu?d from Goleta Point to Santa Barbara Point* a seaward progression of coarse to fine sizes is present. Sediment types are sands and silty sands (Pig. 7). Median diameters (Fig. 12) indicate that fine sand is close to shore and that there is a seaward gradation to very fine Band and ooarse silt. The deposits have average sorting (0.50 to 1.00 phl-units) near shore and poor sorting (greater than 1.00 phi-unite) on the outer part of the shelf (Pig. 18). Both skewness values are strongly posi tive (Pigs, 27 and 34)» again showing proximity to a fine grained sediment source. This part of the shelf is receiv ing small amounts of land-derived detrital sediments vhloh 89 are now being distributed by wave action, producing a sea ward ooarse to fine progression* In summary, Point Conception Shelf is characterized by complexity of its sediment pattern* Some aaterials are received from land and distributed by waves* Portions of the shelf, however, are not now receiving significant amounts of sediment from land, and residual bottom deposits result from reworking by an advancing surf zone* Carpinteria Shelf-rise Deposit The shelf between Santa Barbara Point and Port Hueneme trends in a northwesterly direotlon, is 35 miles long and 10 miles wide* Bottom slope averages 30 feet per mile, or 0*28°* ContourB of the bottom (Pig* 56) show that the shelf is not a smoothly sloping plane, but con sists of irregularities that indicate the presence of structural features and areas of variable sedimentation rateb after shelf formation. Depth contours, based upon United States CoaBt and Geodetic Survey depth recordings, reveal a linear elevation trending east-west and inter secting the coast in the vicinity of Oarplnterla, Cali fornia* This shelf-rise is 8 miles long, 2 miles vide, % and rises 20 feet above the general level of the shelf floor* It begins 2 mlleB from shore south of Carpinteria and extends westward to 3 miles south of Santa Barbara Point* Although this rise extends obliquely aoross the SCf I D ' 4 0 .PT.LAS ftTAS F lg u r* 66 SUBMARINE TOPOGRAPHY OF MAINLAND S H E L F -S A N T A BARBARA TO PORT HUENEME 91 shelf, it parallels the general trend of Santa Tnes Mountains to the north. It aligns closely with an anti cline of Pico (Pliocene) sediments extending eastward froa Point Las Pitas (Thomas, et al., 1954) but is offset 2 ■lies from that anticline. Existenoe of the shelf-rise is further demonstrated by bottom sediment characteristics. Thirty samples show the shelf-rise consists of sand, with silty sand on the inner and outer ends (Pig. 8). The southern flank grades into finer silts on the central shelf plain through a distance of 4 miles. The northern flank, in contrast, abruptly changes from sand to clayey silt within a distanoe of 1 mile. The fine-grained sediments ocoupy a trough-like depression. Median diameters of the shelf-rise indicate the presence of some medium Band (Pig. 13), but mostly very fine sand. Sorting is moderate to poor (Pig. 19)* Plrst phi skewness is weakly positive (Pig. 28), and second phi skewness is strongly positive (Pig. 35), indicating move ment of a small amount of fine material onto the rise. Prom second phi skewness data the northwest flank has a smaller surplus of fines than the southeast flank. Sand fraction of the shelf-rise is probably a reeldeal remnant of resistant Pllooene rook projeoting through unconsolidated oover. Continuation of the Pioo anticline on the mainland is suggested, but the submarine rise is offset northward. Trends of the two features are ^ parallel. Examination of ooarse fractions from the rise shows high oontent of the authlgenio mineral glauconite. Of an irregular papllliform tjpe (Pratt* 1962), this glauoonits is similar to grains in Plioosns rook fragments in cores from the same region. Glauconite oasts of fora- minifera indioate deposition in deeper water than now exists on the mainland shelf. In addition, foramlniferal content of the non-glauoonitlc part of the shelf-rise indicates Pllooene age (Johanna Reslg, personal communica tion) . One sample near the shoreward end of the rise is composed mostly of larger invertebrate shell fragments. Acoustic reflection studies indioate this structure is an anticlinal nose having unconsolidated sediment oover of 3 to 6 feet and some exposed consolidated rock (P. G. Moore, personal communication). Exposure of a Pliocene outorop on the sea floor indicates an area of non-deposition (the shelf-rise) exists adjacent to an area receiving abundant land-derived material from Santa Clara and Ventura Rivers. Wave action is evidently keeping the elevated area swept dean of fine debris. Santa Clara Prodelta Beposit Bottom contours of southeastern part of the wide shelf (Fig. 56) show a gradually steepening bottom slope from shore to outer edge. Contours, which west of Point ^ La* Pita* trend parallel to shore* swing seaward in a broad arcuate pattern indleating shallowing of the sea floor that extends as far as Hueneae Submarine Canyon* a longshore distance of 16 miles* This low arching bulge In the sea floor Is the prodelta of Santa Clara Hirer. Seaward boundary of the prodelta Is the mainland slope* where the sea floor dips more steeply Into Santa Barbara Basin, 1500 feet below sea level. This prodelta has a seml-olrcular plan with a radius of 8 miles and extends from Point Las Pitas to Port Hueneae• It is bounded by Hueheme Canyon on the southeast* a flat oentral shelf plain on the northwest, the mainland slope on the seaward side, and Oxnard Plain (Thomas, e£ al.* 1954-) landward of the shoreline. The map of sediment types (Pig. 8) shows a general seaward gradation from sand near mouth of Santa Clara Elver through silty sand* sandy silt* silt, to clayey silt* which is encountered about 10 miles from the river mouth. The axiB of decrease In grain sise is oblique to the axis of the shelf* but is perpendicular to shore where the river discharges. Outer limit of the topo graphic feature coincides with the boundary between silt and clayey silt. Sediments are well sorted near shore* have moderate sorting farther seaward, and are poorly sorted about 7§ miles from the river mouth (Pig. 19). First phi skewness values are weakly positive near shore and strongly posltlvoj In deeper water (Pig. 28), whereas eeoond phi skewness values are strongly positive throughout the entire pro delta (Pig. 35)• This indioates that fine material occurs as a snail surplus throughout the region and as a greater surplus only on the seaward part of the deposit. Vawe aotlon is not sufflolent to distribute the sediments evenly owing to the great abundance of material supplied by the river. 1 surplus of fine grains in small quantities re sults. Sediments from the outer part of the prodelta oon- taln large quantities of plant fragments that have been carried to sea by the Santa Olara Elver (Uohupl, 1961a) and deposited with the fine-grained sediments near edge of the shelf. Seaward bulge of depth oontours, radial progression of ooarse to fine grains, and abundance of plant debris Indioate these sediments oame from Santa Olara and Ventura Rivers very recently. Las Pitas Mud Deposit Between the Oarpinteria shelf-rise and the Santa Olara prodelta, the sea floor forms an elongate depression trending almost east-west (Pig. 56). In this depression are the finest-grained sediments that ooour on the main land shelf. They contain more than 10 per oent Clay and are mostly olayey silts (Pig. 8). Median diameters (Pig. 13) are in fine silt sizes (0.016 mm to 0.008 mm). The __ 95 central part of the fine deposit contains the smallest medians (0.007 mm to 0.008 mm) of the entire shelf. On the east* the Las Pitas mud deposit Is bounded bj the Santa Olara prodelta deposit* with vhich It forms a continuous progression from medium silts to ooarse silts at the boundary. On the vest* the mud deposit meets the Carpinteria shelf-rise. Hear the latter* grain else of the mud Increases* possibly ovlng to transportation of some ooarse sediment Into the mud region. Band content of the Las Pitas mud deposit (Pig. 42) 1b generally less than 1 per cent and consists almost exclusively of plant debris* organic aggregates, and shell fragments. ▲ seoond smaller area of equally fine-grained sedi ments oocurs betveen the shelf-rise and Santa Barbara Point. Here clayey sediments (Pig. 8), with medians (Pig. 13) of fine silt sizes (0.016 mm to 0.008 mm), are situated betveen, but In close proximity to, sands of Santa Barbara Point and Carpinteria shelf-rlBe. Continuity of the topo- graphlo rise (Pig. 56) 1b the basis for separating the Las Pitas mud deposit Into tvo parts, one on either side of the elevated area. Sorting of the Las Pitas mud deposit (Pig. 19) Is poor to very poor (values greater than 1.00 phi-units). Both first and seoond phi skevness parameters have veakly positive values; that is, they have size frequency curves vhloh Indicate only a slight surplus of fine material. Seoond phi skewness values (Pig. 35) of Las Pitas mud (0.00 to 0.90) are in narked contrast to those in the ad jacent Santa Olara prodelta9 where second phi skewness is strongly positive (values greater than 0*90). This sug gests that Santa Clara River iB a source of abundant fine sediments, and that a slight surplus is settling on the prodelta. Parther from the river south, where sedinents are finer because of greater distance from shore, fine sedinent registers as a more normal component of the total sample. In summary, the mainland shelf between Santa Barbara Point and Port Hueneme (Wimberley, 196?) consists of three sedimentary units, one of which is divided into two parts by a topographic high. The map of sand content (Pig. 42) well illustrates these units. Near the mouth of Santa Clara River (Just south of Ventura) sand content exceeds 75 per cent, and radially from the river mouth sediments grade through decreasing sand values to edge of the pro delta. Beyond the prodelta is a oentral shelf plain con sisting of fine sediment (fine silt and very fine silt) that has settled to the bottom in a seaward-dipping depression. Possibly highlands on either side (Pig. 57) provide sufficient protection to permit deposition of fine grains which elsewhere are found only in deep basins of the continental borderland or behind man-made breakwaters. The shelf-rise near Carpinteria, the protecting feature on the Jto- ja o - H ! s x i » ioh to- M M T A C U IU P A O O E L .T A LAS PITAS M UD GRAIN SIZE BOTTOM TOPOGRAPHY T ~ tx ~ r to T~ T a ~r o ~r o i i m i n k s m m u s mm s a n h cuum m vcr m outh P lg u r « 5 7 GRAIN S IZ E AND BOTTOM TOPOGRAPHY SANTA BARBARA POINT TO SA N T A CLARA RIVER e -a 98 northwest* is a topographic expression of underlying Plio cene rock. At the sea floor surfaoe this rook is weathered and disaggregated hut not transported. It is a region of non-deposition containing a residual sediment (Beery* 1952). Exposure of a Pliocene outcrop on the sea floor indicates that an area of non-deposition exists adjacent to an area receiving abundant land-derived material (the prodelta of the Santa Olara River)* wore material ap parently than anywhere else along the southern California coast. Pliocene rocks extend upward through the Recent sediment like an island and are slowly being buried by river-delivered sediment. Absence of fine material on the shelf-rise such as lies in the oentral shelf depression and In the trough near Santa Barbara Point is due to the capa city of the ocean even in water depths of 200 to 500 feet to winnow (or keep in suspension) fine-grained sediment until it has moved seaward beyond the mainland shelf. Sea mounts on the floor of the deep ooean (Hamilton* 1956) and submerged banks on the continental borderland (Uchupi* 1961b) hare similar characteristics of ooarse material on top surrounded by fine material at the base. Santa Monica Shelf Complex Santa Monica Bay is a 15-mile indentation of the coastline between Santa Monica Mountains and Palos Verdes Hilla. The hay* and particularly its sediments* were studied in detail by Terry* Keesling* and Uchupi (1956). Highlands that border the bay are uplifted blocks separated from the Los Angeles Plain by east-west trending faults* Hirer drainage into the bay is mostly from the Santa Konioa Mountains* The southern part reoelTes almost no land drainage because high sand hills border the bay from Playa del Rey to Palos Verdes Hills. Until the mld-19th Oentury* Los Angeles River followed the present tfoarse of Ballona Greek and emptied into Santa Monloa Bay* Sub sequently its course ohanged to discharge into San Pedro Bay* Presumably greater quantities of sediment were contributed to the bay before the drainage ohange. In Santa Monica Bay the shelf break occurs at 270 feet. The arcuate nearshore part of the bay shallower than 270 feet consists of a smoothly sloping (0*5°) surface (Pig* 58)* A central plateau (called the "central shelf projection" by Terry* Keesling* and Uohupl) is a wide flat area between submarine canyons where the 300-foot depth contour changes from a gentle concave-west curvature to a westward bulge. The central plateau has variable relief of 10 to 40 feet. Two submarine canyons incise the shelf: the northern one* Santa Monica Canyon* is relatively wide with gentle flank slopes; the other* Redondo Canyon* is narrow and has steeper flanks. Santa Monica Canyon extends to within 3f j H H S ' * *« 3 * o r i • 0 I?! I I pro £ o •d k* HO * • 0 H# <00 SM s 1. SUBMARINE TOPOGRAPHY SANTA MONICA IAT C Q N t p u P iN TCRyALS SANYA MONICA 101 miles of shore, whereas the head of Redondo Canyon Is within a few hundred feet of shore. Data of shelf sediments from the 1956 study of Santa Monica Bay were plotted and contoured in Figures 14, 20, 29* and 36 in combination with 41 samples collected and analyzed for thiB study. The more recent samples indioated no significant change in bottom sediments during the Bhort intervening time between collections of the two series of samples. Sediment types in Santa Monica Bay are silts (Fig. 9) in the northern part, sandy silts in the nearshore vicinity of Santa Monica, and sands and sandy silts grading southward to finer sediments from the mouth of Ballona Greek to Bedondo Canyon. The southward progression of fine-grained materials may represent contribution of sedi ment by Ballona Creek to the bay. The sediments are mostly quartz-feldspar sands of gray or olive green color. Rock fragments ooour near the outer marftin of the shelf just north of the central plateau. Patches of glauoonitlo sand (that is, at least 20 per cent glauconite grains) occur near the shelf-break and on the flanks of submarine canyons. Phosphorite nodules, as well as glauconite and shell sand, occur on the central plateau between topographic protuberances. Several patches of iron- stained coarse to medium subangular sand having a distinct reddish or brownish color occur in the bay. Onejpatch of __ 102 brown sand and abundant shell fragments is near shore be tween Redondo Canyon and Palos Verdes Hills. Other patches of more reddish sand and lesB shell material ooour in shallow water near Venice and Playa del Hey. In Santa Monica Bay these red sands are shallower than 75 feet. Median diameters in Santa Monica Bay (?ig. 14) show a seaward progression from very fine sands to ooarse silts in the northern part of the bay. Contours of medians bulge slightly seaward south of the mouth of Ballona Creek. Most sediments on the central plateau are very fine sands ( m e d l a n B 0.062 mm to 0.125 mm), but some samples are as coarse as 0.60 m m . 1 strip of coarse silt extends parallel to shore between mouth of Ballona Creek and the central plateau. The significant phenomenon in Santa Monica Bay is the progressively seaward decrease in grain else on the northern shelf and a similar decrease part way aoross the southern shelf. About 4 miles from shore this trend changes (minimum median diameter of 0.038 mm) to one of increasing grain Blze toward outer shelf and central plateau, where medians are nearly 1 mm. The arcuate nearshore region consists of well sorted and moderately sorted sediments (Pig. 20), whereas the outer shelf and central plateau contain sediments that are poorly and very poorly sorted. Suoh poor sorting may be attributed to: (1) lack of wave action at greater water 103 depths, (2) multiple sediment origin, such as development of authigenlo minerals, shells, or fragmentation of sub merged rook, or (3) relict and residual features, such as lag deposits left bj an advancing shoreline. The marked difference in sedimentary trends between nearshore and outer regions requires different explanations of sediment origin in the two areas. Sediment skewness is also different in the two regions. The shoreward arouate rim of the bay has a weakly positive trend which seaward changes to negative, but the boundary between the two areas lies farther shoreward than is the change between trends of median diameters or sort ing. Thus skewness indicates a surplus of coarse sediment farther shoreward than do medians. Negative skewness on the seaward fringe of the decreasing grain Bize and well sorted sediments reflects mixing of some coarser particles with finer-grained land-derived materials. Bottom turbulence to cause mixing and possibly shoreward migra tion of coarse particles dre suggested. This seems to be a plausible explanation for the presence of small amounts of additional coarse sediments along the outer margin of the area of present deposition. The pattern of second phi skewness is intrloate (Fig. 36). Positive Bkewness is confined to the very near shore area and to stringers whloh extend across the shelf in a somewhat irregular patchwork. Inasmuch as seoond phi 104 skewness records the extreme tails of the grain size fre quency distribution, this suggests even farther landward ■lgration of a saall amount of coarse material. At least, the Increased areal extent of negative values of seoond phi skewness compared to first phi skewness and of first phi skewness to other sediment parameters indicates proximity of a coarse-grained area to the fine-grained area. Presence of suoh a coarse area is first revealed by extreme ends of each size frequency distribution, suoh as is re corded by the 5th peroentile. In summary, sediments on Santa Monica Shelf are a complex of reliot materials and modern materials contributed by erosion of nearby land areas, followed by reworking by the ocean at its present level. A general progression of coarse debris near shore to fine offshore exists exoept on the central plateau and in a few other soattered places, where coarBe rock fragments, authigenic minerals, and shell materials Indioate areas of non-deposition. Sorting and skewnesw values differentiate betveen modern detrital sedi ments and those of the central plateau. Veil sorted fine grained Bediments are being deposited on the shoreward detrital province; the central plateau has poorly sorted material with minor surpluses of coarse particles. San Pedro Shelf Complex 105 San Pedro Shelf le a 12-mlle wide area between the 1400-foot highlands of Palos Verdes Hills on the west and a low coastal plain on the east and north. Shelf break oc curs at about 240 feet. The shelf Is a smooth plane slop ing gently at about 0.3°* except for a low northwest- southeast topographic nose which projects across the central part. 1 roughly circular depression about 1 mile in diameter and about 10 feet deep exists behind the nose. ▲ man-made breakwater nearly enoloses one-fifth of the shelf, forming Lob Angeles Outer Harbor. Los Angeles Hirer now flows into the Outer Harbor behind the break water, and the San Gabriel Hirer flows onto the shelf im mediately east of the open eastern end of the breakwater. At the outer edge of the shelf are two sea ralleys; the western one, San Pedro Sea Valley, trends generally east- west, but swings northeast toward the mouth of the San Gabriel Hirer. No topographic erldence remains of a con nection between rirer and sea ralley from shore to water depths of 20 fathoms because the channel has been burled by later sediments. Another sea ralley has two branches whloh cut the shelf as shallow as 160 feet before losing their identities. San Pedro Shelf was inrestigated in detail by Moore (1954) and by Sterenson, Oonrey, and Gorsllne (1954). Maps of sediment parameters in this report are based upon Moore's 75 samples coupled with data from 53 samples sub sequently analysed for this work. Moore reported a large area of the central shelf where rook samples were ob tained, indicating exposure of an anticline at the sur face. Middle Miocene, Late Miocene, and Early Pliocene rock fragments were dredged from the sea floor. This rooky area is flanked by unoonsolidated yellowish-brown, coarse to fine sand that oovers about 5 per oent of the San Pedro Shelf. Moore classified the rest of the sedi ments (other than the rocks and the brown sand) into three groups of sands and a "very fine sand to day" behind the breakwater. Construction of the breakwater oaused fine sediments to cover the area behind it rather than allow this material to remain in suspension for transport aoross the shelf to deeper waters of offshore basins. Presence of fine sediment behind the breakwater therefore lndloates little or no sand contribution to the shelf at the present. Sand does exist on San Pedro Shelf, probably remaining from former environmental conditions that allowed it to ac cumulate • Median diameters (Fig. 15) are mostly in the very fine sand range (0.062 mm to 0.125 mm). This sand is an olive green or gray quarts-feldspar sand having median diameters slightly larger than 0.062 mm. The area of out cropping rook and its surrounding yellowish-brown ooarse Jfco^ medium Band has medians as large ae 0.40 mm. Another ooarse area to the east has medians up to 0*30 mm. In the southeastern part of the shelf, medians are slightly less than 0.062 am hut not less than 0.034 mm. Median diameters of fine sediments behind the breakwater range from 0.062 mm near the eastern end to 0.006 mm near the oenter. In ad dition to yellow-brown sand surrounding the oentral shelf rocky area, one sample of reddish quartz-feldspar sand was found In the northern part of the shelf very near the mouth of the San Gabriel River. Stevenson, e£ al. (1934) reported red sand off the river mouth In water as deep as 60 feet. Red sand of the western portion of the area Is probably olosely related In origin to nearby rooks; no rooky areas occur near the eastern red sand, and Its origin is more closely related to that of red sand in Santa Monloa Bay. Sediment sorting (Fig. 21) on San Pedro Shelf Is mostly in the 0.00 to 0.30 phi-units range (well sorted). Rzceptlons are the outer shelf where values indioate moderate to poor sorting and the inner shelf near the harbor where values are similar. Average sorting (standard deviation) behind the breakwater Is 1.23 phi- units, whereas the average for San Pedro Shelf Is 0.40 phl- unlts. It Is noteworthy that sorting of yellow-brown sand surrounding rook outcrops on the central shelf Is no dif ferent than sorting of olive green and gray sands elsewhere 108 on San Pedro Shelf. Pirat phi skewness (Pig. 30) shows most of the shelf to be weakly positively skewed, including at least one-half of the region behind the breakwater. Two major exceptions to this are negative skewness around rocky areas and a nearshore area extending southward from the mouth of San 4 Gabriel Elver. These areas are where red (or brown) sand occurs, and positive skewness indicates a surplus of ooarse grains as compared to "normal" sediment distribution. These areas of positive Bkewness extend into olive green and gray very fine sand areas and may Indicate a slight degree of mixing of coarse grains into finer samples. Second phi skewness values of Moore's samples were not available, so the map (Pig. 37) is based upon fewer samples than the other maps of San Pedro sediments. The 53 samples later analyzed for this study show the shelf to be mostly weakly positively skewed with the rooky area and the zone south of San Gabriel Elver negatively skewed. The outer shelf and an area just east of the open eastern end of the breakwater are strongly positively skewed, a character!atie whloh first phi skewness did not show. Both of these areas are immediately adjacent to fine-grained areas, and their positive skewness (indicating additional fine material) reflects this proximity. In summary, the sediments of San Pedro Shelf are a complex, consisting mostly of olive green and gray very 109 fine* well sorted sands showing no correlation of grain size with water depth nor distance from shore. They are mostly slightly positively skewed. Exceptions are ooarse red (or brown) sands surrounding a rooky area on the oentral shelf and near San Gabriel Hirer, and finer sedi ments (fine to ooarse silts) behind the harbor breakwater. Because any sediment contributions to the shelf are trapped behind the breakwater or carried beyond the shelf to deeper water, the sands on the shelf must be remnants from earlier sediment deposition or formation. Probably these sands were left as sea level slowly returned following the last glacial lowering. Oceanside Narrow-shelf Complex The shelf from Newport to Point Loma is narrow com pared with most of the southern California mainland shelf. The average width is 3 miles and maximum width is 6 miles (Pig. 4). Land drainage is by numerous rivers, lnoluding the Santa Margarita, San Luis Hey, and Esoondldo Hi vers, which flow westward from the Santa Ana Mountains. Many smaller streams are ephemeral and their mouths are blocked by sand bars, except in winter. The shelf-break progres sively deepens from 240 feet in the north to 320 feet in the south, which reflects the general westerly downwarp of the continental borderland of southern California (Emery, 1958). Sediment types (Pig. 10) on this shelf show a regular! 110 progression from eande along shore to silts offshore. Median diameters of sediments close to shore Indioate the domlnanoe of very fine sand (Fig. 16). The remainder of the shelf deposits as far south as Oarlsbad are coarse silts with median diameters rarely less than 0.040 mm. Correlation of median diameters with water depth (Fig. 59) indioates that the shelf between Oorona del Mar (near Newport) and Carlsbad has been strongly lnfluenoed by waves which move finer material progressively farther from shore. The nearshore coarser sediments are well sorted (Fig. 22) whereas those in deeper water have average sort ing. First phi skewness (Fig. 31) shows nearshore detritus to be weakly positively skewed, and the area seaward Btrongly positively skewed. Seoond phi skewness (Fig. 38) shows that all sediments are strongly positively skewed. In other words, an exoess of fines is being deposited over the entire shelf, but in larger amounts at the outer half. The Carlsbad-to-La Jolla section is different from the northern area. Sediments a r e coarser, being mostly sands and some Bllty B a n d . Median diameters are in the very fine sand range (0.062 mm to 0.125 mm) from shore to edge of the shelf. MoBt s e d i m e n t s are moderately sorted (0.50 to 1.00 phl-units), s h o w i n g no correlation with water depth, such as oocurs farther north. Skewness values show no geographlo grouping, except near Del Mar, where sediment curves exhibit a zone of weakly positive second phi skew- DEPTH IN FATHOMS 111 10 H 20 - 30 - 4 0 - 8 0 - 6 0 - 70- 80 - 90 MEOIAN DIAMETER IN •075 .0 6 0 I ________ I __ • • #• MEDIAN DIAMETER VS CORONA DEL MAR TO Figure 59 W AT ER DEPTH CARLSBAD 112 ness. Inability of the ocean to rework and progressively distribute sediments in the area of Carlsbad may partly be result of protection afforded by the projecting point of land at La Jolla. This projection may cause wave refrao- tion to the extent that sedimentary debris is kept In sus pension and transported beyond the shelf. Coarser material of the Carlsbad-to-La Jolla shelf possibly indi cates lag deposits left by an advancing shoreline and remaining uncovered by modern detrltal materials. Sediments from La Jolla to Point Loma, where the shelf is also narrow, are sands for more than a mile from shore. Outer part of the shelf is sandy silt. An elongate tail of finer sediments (silty sand near shore and silts farther Beaward) extends from the mouth of Mission Bay and curves southward. Sandy silts on the outer half of the shelf terminate Just south of Point Loma. Progression of coarse to fine sediments in a seaward direction on a narrow shelf segment adjacent to high land illustrates the ef ficiency of waves in sorting and distributing sediments from a nearby source. Seaward sediment-slze decrease terminates at the southern limit of the narrow shelf (at Point Loma). Median diameters on the shelf between Point La Jolla and Point Loma show medium sands (0.25 mm to 0.50 mm) around Point La Jolla and a general decrease in grain size both seaward and southward along the coast (Fig. 16)* Seaward, sediment grain size decreases to coarse silt (0.031 mm to 0.062 mm) in water depths of 300 feet. South ward very fine Band occurs in the vicinity of the mouth of Mission Bay, and ooarse silt blankets the outer half of the shelf as far as Point Loma. San Diego Shelf Complex Off San Diego the shelf is nearly twide as wide (10 mileB) as the area Immediately to the north. Shelf break occurs at a depth of about 330 feet. Landward is a gradual slope of 0.2°. Greater width of this shelf exists because of coastal indentation between Point Loma and Los Coronados Islands, 15 miles farther south. The Bhoreline is mostly a low sand spit (Coronado Strand) curving northward from Tia Juana River to Point Loma; the intervening gap is the entrance of San Diego Bay. Incising the shelf as shallow as 37 fathoms is Coronado Canyon. The seaward margin of the shelf north of Coronado Canyon is the shoreward flank of Loma Sea Valley, a straight, gently sloping feature that trends northwest. Beyond this valley is Coronado Bank, a flat-topped area 70 fathoms below sea level. This bank would be part of the mainland shelf if the valley did not isolate it. Emery, et ml. (1952) studied the area off San Diego in detail. Maps of sediment parameters (Pigs. 17, 23, 32, and 39) of 114 this report are the result of combining laboratory analyses of 165 samples from the earlier study with 67 samples col lected later and analyzed for this work. Sediment distribution off San Diego differs from the narrow shelf to the north In that sediment types are mostly sand and sandy silt* Sediments of San Diego Shelf bear greater similarity to those of San Pedro Shelf than to the Intervening area. Another similarity between the two areas Is presence of rook outcrop. The rook is mostly light gray shale of similar llthology to the Cretaceous Ohlco Formation on Point Loma. An area of sandy silt oc curs on the inner Bhelf near Coronado Strand* but this fine grained material may have been introduced by dredging operations In San Diego Bay. The sands are of two colors: one is a fine gray sand occurring in the north* east* and south; the other is a medium to coarse brown sand similar in appearance to red sand on San Pedro Shelf (near the mouth of San Gabriel Biver) and in Santa Monica Bay (near the mouth of Ballona Creek). In contrast to the latter areas* the red sand of the San Diego region occurs in water depths as great as 300 feet. Coarse fractions of gray sand are similar to ooarse fractions of sediments on the narrow shelf to the north* but the fact that gray sand extends seaward to the 300 foot depth contour is in oontrast with the Ooeanside Shelf* where the outer limit is in water depths of about 50 feet 1X5 (Fig. 59)* Presence of sand at much greater distance from shore (7 to 10 miles) off San Diego suggests that gray sand, as veil as red sand, is not modern detrital material distributed by the ocean under present conditions. A more likely explanation is that the gray sand vas left behind after being reworked by the advancing shoreline during glacial rise of sea level. If true, the gray sand of the San Diego region is more closely related in origin to red sand than to gray sand of the Oceanside Shelf. Median diameters do not distinguish mid-shelf red sand from its surrounding gray sand, but the former is coarser, having medians greater than 0.5 mm. Sand content of the red sand is consistently greater than 98 per cent. Plner sediments having medians between 0.125 mm and 0.062 mm occur shallower than coarse gray sand, in water depths of 30 to 120 feet. This is off the mouth of Tia Juana Hlver and extends northward almost to the end of Coronado Strand. Thus south of Point Loma median diameters are either relatively constantly coarse-grained from shore to depths of 300 feet or are somewhat finer-grained shoreward and coarser seaward. North of Point Loma, coarse sedi ments deorease progressively seaward to the upper olass of silt sizes (0.031 mm to 0.062 mm). Beyond Loma Sea Valley, Ooronado Bank caloareous sediments have median diameters greater than 0.125 am. Most of the sediment of the San Diego Shelf is 116 moderately sorted (Fig. 23)* having standard deviation values of 0.50 to 1.00 phl-unlts. This Is true of both red sand and gray sand* but In sone plaoeB red sand Is veil sortedv and one east-vast elongate zone of gray sand Is poorly sorted. Sorting does not distinguish readily be- tveen the tvo sediments of different colors. Values of first phi skewness are veakly positive near shore and oover Increasingly wider areas of the shelf In a southvard direction (Fig. 32). 1 narrov strip of lov negative values extends obliquely northvard across the shelf toward the mouth of San Diego Bay. JLreas of strongly positive skevness occur near the shelf break. First phi skewness, therefore, shows the shelf to be mostly slightly positively skewed with some variations In both directions, ▲gain, no differentiation between red sand and gray sand is suggested by this sediment parameter. Second phi skewness (Fig. 39) shows almost the en tire shelf south of Point Loma to be slightly positively skewed. Exceptions are a continuation of strongly positive skewness southward from outer shelf north of Point Loma and small areas of negative skewness within the red sand. Negative skewness also occurs near shore at and north of Point Loma and near Ooronado Strand, lgain, no striking difference is denoted between red sand and gray sand, but both are distinguished from the narrow-shelf sediments north of Point Loma by lover skewness values. The similarity of sediment parameters in sediments of different colors suggests they were treated by the sea as a unit and deposited without differentiation. Their ooourrenoe in different geographic areas might be ex plained by a difference in sediment origin when they were last reworked. When sea level was lowered perhaps 300 feet during the last glaeial advance, the exposed San Diego Shelf must have developed coastal features, suoh as dunes and beaches at the shore, river bars and blanket sands on the lowlands nearby. If the red stain on the grains Indicates an oxidized Bubaerlally-foxmed deposit, the red Bands most likely represent coastal dunes and the gray sands are materials left by rivers. Thus a somewhat different geographic distribution resulted. Then as the glaciers receded and sea level rose across these sands, they were reworked unpreferentlally and redistributed ac cording to their hydraulic properties but not moved any great distance from the previous source area. Because sea level rose relatively rapidly, coarse sands were left be hind. They have not been covered by finer sediments from * present land sources because modem sediments are trapped within San Diego Bay, and the contribution of the Tia Juana River, other than very fine sand Just north of the river mouth, does not have great areal extent. These uncovered gray and red sands, then, may be remnants of the conditions before sea level advanced. 118 Nearshore Environment i collection of sediment samples from the littoral zone was made using a motor launch and hand-operated sampl ing gear. 1 total of 110 samples was taken along 33 pro files (Fig. 60) oriented perpendicular to shore. These profiles extend from the surf zone to water depthB of 30 feet. The nearshore profiles generally show a decrease in grain size from the shallowest sample to water depths of 15 feet. Farther from shore, decrease in grain size with distance from shore is less distinct, but a tendenoy of decreasing sediment size continues to water depths of 39 feet. Variations from the trend are the result of shell material or nearby sources of coarse clastio particles. Size characteristics of samples from the same depth of water are not oomparable from profile to profile because of looal environmental and source factors. Samples from the nearshore environment are brown or gray in contrast to olive-green and gray sediments of most of the mainland shelf. The material is well sorted (standard deviation values less than 0.50 phi-units) and generally has negative skewness values, indicating a surplus of coarme particles. This seems to be true of all near shore sedlmentB. Samples nearest shore have negative values for both skewness parameters, but in some places 119 II 7 ° 110 ° L_. 119° 120° 121° iTA. BARBARA PT. CONCEPTION P T. DUME 34 N E W P O R T -33° SAN D IE G O -32 50 PROFILES i i - S T A T U T E M IL E S 121° 120° 119° LOCATIONS OF SAMPLING PROFILES OF THE NEARSHORE ENVIRONMENT Figure 60 120 there le a transition from nearshore negative values to positive values on the Inner Bhelf. Negative values of nearshore profiles are In marked contrast to positive values of most of the mainland shelf* This results from proximity to beaches and vigorous sediment transport by vaves breaking along the shore. Samples from shallow water depths along the entire shore are more closely related to each other In sediment characteristics than they are to samples from deeper parts of the mainland shelf. Nearshore materials are considered as a separate sedimentary unit comparable In significance to other sedimentary deposits on the mainland shelf. The geographic distribution 1b somewhat different, because It extends discontlnuously the full length of the mainland shelf from Point Conception to Mexico. The nearshore faoies is transitional to deeper water sediments and shows marked ohanges in sediment characteristics within a short seaward direction. Nearshore sediments have relatively constant characteristics parallel to shore. GENERALIZATIONS ABOUT THE MAINLAND SHELF Sediment Variation with Time 0f the earlier sediment Investigations on the southern California mainland shelf* the following studies covered sufficiently large areas to be valuable for Infor mation concerning sediment change with time: (1) Santa Monica Bay (Shepard and Maodonald* 1936* and Terry* Keesling* and Uohupl* 1956)* (2) San Pedro Shelf (Moore* 1951* 1954, and Stevenson* Conrey* and Gorsline, 1954)* and (3) San Diego Shelf (Emery* Butcher* Gould* and Shepard* 1952). Original laboratory analyses data for the Terry* et al.» study and the Bsery* et al., study were acquired* Cumulative grain size frequency curves were redrawn and sediment parameters were computed* For the Shepard and Maodonald study* only sediment curves could be found* from which the phi percentiles were derived and sediment para meters computed. Moore's original data and sediment ourves oould not be located (Moore, personal communication)» but four sediment parameters (median diameter* phi standard deviation* phi skewness* and water depth) were available (Moore* 1951)* This provided some, but not oomplete* In formation for comparison with the present study of the San Pedro region. Also a report* ULthout all illustrations* 122 concerning L o b Angeles Harbor Approach Area, prepared by Stevenson, et al., (1954) was available. Santa Monica Bay The study of sediment samples from Santa Monica Bay In 1936 (Shepard and Macdonald, 1938) included size analyses of 133 samples. The majority of these, however, were concentrated in the region of submarine oanyon heads, and only 47 were from water depths less than 300 feet and epread throughout the bay. Mostly they were from two straight profiles, one extending eastward from the central plateau, the other southeastward (Fig. 61). Sediment parameters of Bamples collected in 1955 were plotted, contoured, and oompared with the information from samples taken for the present study (hereafter dated 1959, although sampling was spread from 1957 to I960). Negligible difference was found and the information from both surveys was included in preparing Figures 14, 20, 29, and 36. The short time interval between the two sampling programs accounts for the similarity of resulting sediment patterns. Comparison of the Bediments in 1936 to samples taken in the late 1950's reveals a marked decrease in sediment size during the 20-year interval. Along both profiles, sediment grain size in later yearB averaged one phl-unit smaller than in 1936 (Fig. 61). For example, the 0.062 mm SEDIMENT SIZE SANTA MONICA 1936 - 1956 1956 1956 SAMPLE L O C A T IO N S ' 1 9 3 5 S T A T U T E M I L E S F RO M SHORE 1 2 3 124 median diameter contour In 1959 extended essentially parallel to shore and about one-third the dlstanoe from shore to the 300-foot depth contour. Seaward of this line sediments were silts, except for coarse materials of the central plateau. In 1936, In contrast, no samples along the two profiles had median dlameterB finer than 0.062 mm, the boundary between sand and silt sizes. United States Coast and Geodetic Survey Ohart No. 1341a of Monica Bay, California, dated 1877* provides bottom sediment notations for the area shallower than 600 feet. The east-west part of the mainland shelf Is marked as consisting of gray sand on the shoreward half and gray mud seaward. At about the area where the mainland shelf aligns northwest-southeast, which Includes the northern of the two 1936 profiles, bottom sediment is noted as fine gray sand for the most part and as fine gray sandy green mud about two-thirds the distance from B to A (Fig. 61), where the bottom is at depths of more than 30 fathoms. A similar relationship occurs along the southern of the two 1936 profiles, where green mud is recorded along the flank of Redondo Canyon. Elsewhere bottom notations are dark gray sand or rocky. These bottom notations were apparently based upon shipboard descriptions in the late 1800's, when a sediment having a median diameter of less than 0.1 mm might readily have been described as mud. To summarize, the 1877 bottom survey does not disagree with the 1936 survey. 125 Information from the 1936 survey Is based upon only two linear profiles in proximity to the central plateau and is not representative of the entire bay* A change in river drainage occurred in mld-1800's (Emery* I960) when the Los Angeles Elver outlet was diverted from Santa Monica Bay to San Fedro Bay. It is doubtful that this was directly responsible for decrease in grain size during the 20-year Interval beginning in 1936. A more likely explanation is the activity of man* including reservoir construction and reduction of stream flow. San Pedro Shelf Bata from the 1950 study of San Pedro Shelf (Moore* 1954) presented a pattern Identical to the 1959 samples* indicating no significant change during the short 9-year Interval* except for a small area near the entranoe to Los Angeles Harbor. Finer-grained sediments found in the later survey are probably the result of dredging to keep the harbor open to navigation. Both sets of the data souroes were used in construction of Figures 15, 21* and 30. Drainage into San Pedro Bay by the Los Angeles and San Gabriel Rivers occurs only during times of heavy rain* mostly in January and February* when considerable fine sediment eroded from the San Gabriel and Santa Monica Mountains is introduced into the Outer Harbor. Fine sedi 126 ment la being trapped behind Loa Angeles Harbor Breakwater, inasmuch as moBt of the deposits of San Pedro Shelf are aanda coarser than the eilt and clay deposited behind the barrier. San Diego Shelf Comparison of the 1943 data from San Diego Shelf (Emery, e£ al., 1932) with data from samples oolleoted be tween 1936 and I960 shows no significant change. Sediment parameter contours of the two sets of'data superimpose well* except where samples were far apart, and only minor alterations of contours were required to make the two sets of data compatible. Ho major rivers flow onto the shelf, exoept the Tla Juana Blver, which apparently contributes very little sediment to the shelf. As previously sug gested, most of this shelf consists of relict and residual sediments that are not the result of present environmental oondltions. These older deposits remain uncovered by modem sedimentb because of lack of source materials. Any thing delivered to San Diego* Bay by river drainage is trapped within the bay. Thus the sediment pattern of San Diego Shelf has generally remained stable during the 15- year period beginning in 1943 and probably for a much longer time. Geographical Generalizations 127 Shelf Width The southern California mainland shelf consists of four segments having Bhelf widths narrower than 6 miles: Point Conception to Santa Barbarav Port Buenems to Point Dune, Palos Verdes Shelf, and Newport to Point Loma. The four intervening areas have widths greater than 6 miles. No significant difference between either average values of sediment parameters of the wide and narrow Bhelves or between the individual segments of the mainland shelf exists, so Bhelf width does not control the present sediment pattern. Other factors, such as pinpoint oenters of sediment source (for example, the mouth of the Santa Clara Blver), water depth (Oceanside Shelf), and distance from shore (inner margin of Santa Monica Bay) exert greater control on sediment distribution. Considering these factors, there still remain segments of the mainland shelf whose sediment distribution cannot be explained by present environmental conditions (for example, the San Diego region, Carplnteria. shelf-rise, and the shelf from Point * Conception to Santa Barbara). The indication is that sedi ments in these areas are results of processes other than delivery to the ocean by streams and subsequent distribu tion by ocean waves and currents. Sediment 3ouroea 128 Seven major rivers drain onto the mainland shelf* the Ventura* Santa Olara* Los Angeles* San Gabriel* Santa Ana* Santa Margarita* and Tia Juana* Between them* the coast is almost everywhere steep or cllffed. Exceptions are the low-lying coasts of part of Santa Monica Bay* San Pedro shoreline* and the sand spit which nearly closes the mouth of San Biego Bay. As noted* Ventura and Santa Olara Blvers have built a prodelta covering 123 square miles of the mainland shelf. Both the Los Angeles and San Gabriel Blvers deposit most of their sediment in estuaries or be hind the Los Angeles Harbor Breakwater. Santa Ana Blver discharges on the southwestern margin of San Pedro Shelf* where no effect of a sediment contribution is indicated by sediment parameters. Santa Margarita Biver causes a slight seaward bulge of the sediment size oontour and also a marked Increase in mica content to the Bouth of the river mouth. Tia Juana Blver causes a slight seaward bulge of sediment contours alBO* particularly sediment skewness. In summary, importance of rivers as sediment sources is moderate near most rivers, with the exception of the vicinity of Santa Olara and Ventura Blvers, where it is great. The difference in magnitude results from the pre sence of a higher land mass and steeper river gradients. Elsewhere than near the major rivers, sediment patterns are 129 most Btrongly influenced by such factors as direction of wave approach or lack of sediment supply. Influence of Submarine Canyons Six submarine canyons (Hueneme» Mugu, Dume, Redondo, Newport, and La Jolla) constitute major lnclsements that extend across the mainland shelf to within a mile of shore. They font barriers to longshore bottom sediment movement except immediately adjacent to beaches. Any sediment moved parallel to shore in deeper water fallB into the canyons and is carried seaward by turbidity currents that periodi cally move along canyon axes. Four other submarine canyons (Santa Monica, San Gabriel, Carlsbad, and Coronado) do not extend as far towards shore. If sediment movement occurs in the8e canyons, the materials must have come from the middle or outer shelf. Emery and Hulsemann (1963) give a detailed description of these submarine canyons. Ocean waveB approaching the mainland shelf are retarded sooner over the shelf than over the deeper bottom of a submarine canyon. Wave fronts over a canyon cor respondingly bend, forming a shoreward bulge, and more wave energy is applied to the sea floor on the flanks of submarine canyons than is available at the same water depths elsewhere. Thus, mainland shelf sediments may be coarser or better sorted In the vicinity of submarine can yons, where additional energy prevents deposition of fine 130 particles. Furthermore, If waves approach the mainland shelf obliquely, a difference in sediment characteristics on the two flanks of the canyons might be expected. Average sediment parameter values were determined for areas around each of the 10 submarine canyons. In the graph (Fig. 62), the central blaok dot represents averages of samples on corresponding left or right flanks (looking shoreward) of each canyon. These dots are connected to the central dot representing total averages by straight lines; thUB, the slope of the connecting lines Indicates relative change from one side to the other. Circles represent averages of the mainland shelf segment in which the canyon exists. Averages of grain median diameter of eight oanyon flank areas are between 3.40 0 and 4.00 0 (0.095 mm and 0.062 mm). The Carlsbad Canyon flank area is markedly finer (4.77 0 or 0.037 mm), and Coronado Oanyon is coarser (2.38 0 or 0.192 mm). Oarlsbad Oanyon lies in an area of modern sediment deposition whereas Coronado Canyon is in an area of coarBe relict deposits. The average of diameters for the canyon flanks is coarser than the average size of sediments of the mainland shelf segment everywhere except near San Gabriel and Carlsbad Canyons. Both do not fully incise the mainland shelf, which partly explains the absence of the expected effect of a canyon on bottom sedi ments. I FIRST PHI STANDARD PHI MEDIAN PHI SKEWNESS D I A M E T E R DEVIATION f \ > <* U H U E M E M E M U G U C A N Y O N D U M E C ANYON S A N T A MONICA C A N Y O N C A N Y O N e- S A N GABR IEL C A N Y O N N E W P O R T C A N Y O N C A R L S B A D C A N Y O N L A J O L L A — C A N Y O N C A N Y O N < C O R O N A D O 132 111 but three canyons (Mugu, Newport* and Coronado) have coarser sediment on the right flank. If it 1b as sumed that bottom movement of fine sediment is inter rupted by a submarine canyon and coarse sediment is "downstream*" then the implied direction of bottom sedi ment movement in the vicinity of each oanyon is: 1. Hueneme Canyon: eastward. This is possible be cause of the nearby source of abundant fine grained sediment discharged by Santa Olara River. 2. Mugu Canyon: westward. Because Mugu Canyon is so close to Hueneme Canyon, sediment supply is cut off by the latter, possibly accounting for the Implied (but not necessarily real) westward movement of bottom sediment. 3. Dume Canyon: eastward. This is possible, but the sediment source must be mostly from cliff erosion of the Santa Monica Mountains. 4. Santa Monica Canyon: southeastward. Sediment source is Btream Introduction, cliff erosion, and sediment movement around Point Dume. 5. Redondo Canyon: northwestward. 8ediment para meters of the two canyons within Santa Monica Bay are reversed with respect to the canyon axes; that is, properties that are relatively higher on the left flank of one canyon are higher 6. 7. 8. 9. 10. 133 on the right flank of the other canyon. If wave approaoh is from the southwest* wave frontb first encounter two headlands* Point Dume and Palos Verdes Hills. Ware fronts bulge Bhoreward centrally following the con figuration of the arcuate shoreline. 1 long shore movement of sediment from the two head lands toward the center of the shoreline arc results* thus causing a southeastward sediment movement toward Santa Monica Canyon and a northwestward movement toward Redondo Canyon. These movements are reflected in the finer- grained sedimentB "upstream," as indicated in Pig. 62. San Gabriel Canyon: eastward. Newport Canyon: westward. Sediment character istics indicate that the shelf southeast of Newport Canyon is receiving abundant Bediment but the area northwest 1b reoeiving very little sediment* hence finer sediments are on the east. Carlsbad Oanyon: southward. La Jolla Canyon: southward. Coronado Canyon: northward. The vloinlty of Coronado Canyon is an area where sediment characteristics are determined by other than present environmental conditions. Plank sedi- 134 mentB need not be explained in t e n s of present Bediment movement. In the vicinity of all 10 canyons, flank areas indicate a sediment size discontinuity that suggests reasonable directions of sediment movement, the finer- grained areas being upstream. All canyonB that trend north-south (Hueneme, Mugu, Dume, San Gabriel, and Newport) have better sorted sedi ments on the right flank than on the left flank. Two other canyons (Santa Monica and Redondo) which are within Santa Monica Bay trend east-west. Better sorted sedimentB are on the left flank of Santa Monica Oanyon and on the right flank of Redondo Canyon (Fig. 61). Waves approaoh- ing north-south trending canyons from the southwest would feel bottom sooner and have greater sorting capacity on the left flankB of those canyons. Similarly greater sort ing capacity would be spent on right flankB of east-weBt trending canyons. For Santa Monica Bay the area between the two submarine canyons consists of poorly sorted coarse grained relict deposits that could not be expected to fdllow the above generalizations because of shoreline con figuration. Regional Characteristics Average regional grain size (Fig. 63) is greatest on San Diego Shelf (0.10 mm) where sediments are remnants AVERAGE VALUES SEDIMENT GRAIN SIZE Figure 65 PHI STANDARD PHI MEDIAN DEVIATION D I A M E T E R S E C O N D PHI S K E W N E S S FIRST PHI S K E W N E S S O — r\> ro GJ tn cn w PT.— C O N C E P T I O N S H E L F S a n t a B A R B A R A S H E L F S A N T A S H E L F M O N I C A S A N P E D R O S H E L F O C E A N S I D E SHELF SAN DIEGO S H E L F N E A R S H O R E E N V I R O N M E N T M M Q* OI f r o m f o r m e r e n v i r o n m e n t a l c o n d i t i o n s t h a t n o l o n g e r e x i s t . T h e s e c o n d i t i o n s m a y h a v e b e e n a r i B i n g s e a l e v e l w i t h w a v e s r e w o r k i n g c o a r s e a e o l i a n o r r i v e r d e p o s i t s . Average median diameters of Point Conception Shelf (0.080 mm) and San Pedro Shelf (0.078 mm) are intermediate in value because they too are areas where sediments reflect former conditions. Santa Monica Shelf 1b somewhat finer grained (0.067 mm). Having the smallest average of the entire mainland shelf is Santa Barbara Shelf (0.041 mm), which, although containing some non-modern sediments, is dominated by fine-grained present-day sedimentation from the Santa Clara and Ventura RlverB. Although Figure 63 shows a regional southward trend of increasing sediment coarseness, the trend is controlled more by local sedi mentary conditions than by geographic position. Average sorting (standard deviation) values range from 0.66 phi-units (better sorted) for San Diego Shelf to 1.24 phi-units (more poorly sorted) for Santa Barbara Shelf with a trend of better sorting toward the south (Fig. 63). Santa Monica, San Pedro, and Oceanside Shelves have about equal sediment sorting values, whereas Point Conception Shelf and especially Santa Barbara Shelf sedi ments are markedly poorer in sorting (1.09 and 1.24 phi- units, respectively). This may possibly be the result of east-west orientation of the latter areas and also of off shore barriers which the four Channel Islands (San Miguel, 137 Santa Rosaf Santa Cruz* and Anacapa) form to waves ap proaching from the southwest* Other islands ooour off southern California* but they are not aligned to form ef fective barriers to wave approach. A decrease in skewness values similarly ocours in a southward direction (Pig. 63)* illustrating introduction of fine sediments in all regions* but more so in northern oneB. Santa Barbara and Oceanside Shelves show large positive values whereas Santa Monica* San Pedro* and San Biego areas have lesser positive valueB* The nearshore environment* composed mostly of sand* has negative skew ness* which is true of nearly all coarBe nearshore sedi ment. It is important to note that although average sedi ment grain size is coarser on San Biego Shelf than in the• nearshore environment (Burf some to water depth of 30 feet)* skewneBS of the former is positive and of the latter* negative. The three average size parameters plotted on a three-dimenBional graph indicate they are not entirely independent of one another (Pig. 64). As average median diameter decreases from 3«0 0 to 5.0 0 , sorting becomes poorer from 0.50 to 1.25 phi-units* and skewness in creases from negative values (-0.04) to positive (+0.33)• Their inter-dependence is shown by the heavy line AB in the cube of Figure 64. In a study of river bar sands* Folk and Ward (1957) PHI STANDARD DEVIATION 1.0 V) 136 Figure 64 BLOCK DIAGRAM AVERAGE SIZE PARAMETERS -4 1 .3 .2 0 . 1 o 4- .5 1.0 PHI S T A N D A R D DEVIATION FIRST PHI S K E W N E S S o c ui L lI 2 < Q Z < o LU . 2 'FIRST PHI SKEWNESS x CL PHI S T A N D A R D DEVIATION PHI MEDIAN D I A M E T E R 139 found that the trend of mean grain else versus sorting versus skewness follows a helical path. The resultant line In the blook diagram of Figure 64 is a very short segment that fits well into the helix. These values are averages of the sediments of each mainland shelf segment and hence do not outline the entire helix. Influence of Headlands Smooth arcuate configuration of the southern California shoreline is interrupted by projections of land in nine places. Five of these are major features accompanied by narrowing of the mainland shelf, probably the result of faulting and greater resistance to erosion. These are Point Conception, Point Dume, Palos Verdes Hills, Point La Jolla, and Point Loma. Four others (Goleta Point, Santa Barbara Point, Dana Point, and San Mateo Point) form lesser projections of the shoreline. Where such projections occur, wave refraotlon re sults in a concentration of wave energy on the shelf in front of each point. This may cause a different depositional environment near the points than elsewhere on the mainland shelf, which may be reflected by sediment variation. Such wave energy concentration would have oc curred in the past at intermediate and lowest sea level, providing the shelf floor continues those projections sea ward. 140 Bottom sedimentb are notably coarser In the vicinity of the major headlands than the average sediment (Fig. 65), but the average for minor headlands is about the same as the total average. There are exceptions in that sedimentB in front of Dana Point (a minor headland) are muoh finer than the shelf average, those near San Mateo Point (a minor headland) are as coarse as the major head land sediments, and sediments near Point Bums (a major headland) are about the Bame size as the minor headlands. In general, sediment from the vicinity of major shelf head lands are coarser than the average shelf sediment (4.04 0 or 0.060 mm), and those from near minor headlands are the same size as the shelf average. Sorting aleo s h o w B a differentiation (Fig. 65)• The shelf average is 1.00 phi-units, but areas around major headlandB and two minor headlands are better sorted (about 0.75 phi-units). The other two minor headlands are more poorly sorted (about 1.25 phi-units) than either major headlands or shelf average. These headlands are Goleta Point and Santa Barbara Point, both of which are behind the barrier of the Channel Islands, which might aooount for poorer sorting. Also the shoreline here faoes southward, not directly into oncoming waves from the southwest. Skewness of the major headlands (Fig. 65) approxi mately equals the shelf average (0.20), but sediments of minor headlands are skewed more toward the fine end of the ( f t c 3 o » 01 CO C C I i ► Cl f t *" 2 ° fl * » > < ► o n X X n» n ► > o o O o CO C O CO HI O 2 £ m 2 > 2 30 “* 1 o m x > > O 30 r > > o 2 -t o m c o a ) co H O CO PT. CONCEPTION POINT 0 0 LET A > POINT SA NTA BARBARA P T . DUME P A L O S VERDES H ILLS — V POINT DANA — f SAN MATEO POINT PT. LA JO L L A P T . LOM A co C O at FIRST PHI SKEW NESS PHI STANDARO DEVIATION PHI MEDIAN 0IAMETER 141 142 sediment curve (0.30). Three of the four minor headlands are In areas where fine sediment Is transported from the mountains to the sea by rivers and then distributed on the shelf. This may account for some of the difference In skewness between minor headland areas and average skewness of the entire mainland shelf. Zonatlon of Sediments Questions have been raised about zonatlon of the shelf; that Is, Is the shelf zoned (1) parallel to shore, (2) progressively away from geographic points, (3) pro gressively In a longshore direction, or (4) In some other way. The answer falls Into several categories, depending upon the area. Zonatlon parallel to shore ocours In Bedlments of OoeanBlde Shelf (that 1b, from Newport Canyon to Point Loma), where sediment size generally decreases In an off shore direction. A similar phenomenon ocours in Santa Monica Bay, exclusive of the central plateau. Progressive zonatlon from a geographic point is present on Santa Barbara Shelf, where sediment grain size decreases seaward radially from the mouths of Santa Clara and Ventura Elvers. This progressive variation does not ocour throughout the Santa Barbara Shelf but does exist within a 12 mile radius of shore. These rivers are not continually delivering sediment to the shelf. On one 143 occasion observation from an airplane showed that a spit had closed the mouth of the river. The only possible passage left for drainage of water was through the bar by percolation. Another situation Is equally Important on the main land shelf. Major shelf "zonatlon1 1 Is not parallel to shore, progressive longshore* nor progressive from points. Much of the shelf consists of sediments related to the underlying consolidated rocks of Miocene, Pllooene, and Pleistocene age, which have been tilted and terraced to form the present mainland shelf. Where these rooks were more resistant to erosion, bottom topography extends above the rest of the shelf as, for example, the Oarplnterla shelf-rise, Santa Monica central plateau, the rocky area near San Pedro, and several lesser ridges between Goleta Point and Point Conception. These areas provide Bedlment which has not been transported far and remain coarse grained areas surrounded by flner-gralned, more recently deposited material. Other areas (San Pedro and San Diego) consist of lag deposits left by an advancing shoreline. Their characteristics are blanket-llke sheets with little variation or zonatlon In any direction. The dominant process on the mainland shelf of southern California Is not deposition. Non-deposltlonal (but not eroslonal areas) dominate, although the shelf oonslsts of many sedimentary deposits that have been laid 144 down on truncated edges of older consolidated rock. Only on the Santa Barbara Shelf, the inner margins of Santa Monica Bay, behind the breakwater near San Pedro, and on Oceanside Shelf are conventional processes of sedimenta tion occurring today. Statistical Generalizations Parameter Interrelationships Sediment genesis is neither defined by a single sediment parameter nor by a simple combination of several parameters; If it were, historical sedimentation would be simply a mapping problem. Some combination of sediment parameters might show a differentiation either (1) between individual units, or (2) between units with identloal or similar origins and those of markedly different origin. Folk and Ward (1957)» in a study of significance of grain size parameters, found a degree of Interdependence between various Bediment measures. For example, plotting mean diameter, sorting, and skewness in three dimensions (such as on Fig. 64), they found a helical trend along which rhythmic pulsations of sediment kurtosls or peaked ness of the grain size frequency curve recorded individual sediment generations. The ranges of grain size parameters they found in study of a Texas river bar were much greater than ranges of sediment parameters on the southern Call- 145 fora la mainland shelf, so a similar three dimensional diagram of the mainland ahelf would contain only a short segment of the helix. A plot of skewness versus sorting (phi standard deviation) for the entire mainland shelf shows a scatter of points throughout* but when points on the diagram are examined and their geographic location noted* some interesting features are apparent. Samples from San Pedro Shelf and from San Diego Shelf* both of which have already been described as non-deposltional areas* occur throughout the diagram as a broad scatter (Fig. 66). In contrast* two areas (Oceanside Shelf and Santa Monica Shelf) are located in the much more restricted lower part of the diagram. Samples from the central plateau of Santa Monioa Bay would fill in the remainder of the graph area to show a distribu tion similar to the first two groups. Similarly* samples from one part of Oceanside Shelf (south of the City of Oceanside) also occur outside the area of most points. From the skewness versus sorting graph alone* it might be concluded that a major difference exists between (1) San Pedro and San Diego shelf sediments* and (2) Santa Monica and Oceanside shelf sediments* exclusive of the sub- regions mentioned. Identification of the first group as areas where no modern sediments are presently being deposited and the seoond group as areas of modern deposi tion begins to have a measurable criterion. 146 Point Conception Shelf (that la, between Point Con ception and Santa Barbara Point) has an Intermediate position on the graph (Fig. 66), but with a notable change In trend, which Is diagonal whereas the others are hori zontal. Part of the Point Conception Shelf samples are within the range of the restricted group; the rest are within the range of the larger groups, but the sample ftpread la much narrower. Samples from the nearshore environment oocur on the graph only within the range of the more restricted modero- deposltlonal areas, as might be expected. Skewness values are mostly negative near shore, mostly positive on Point Conception Shelf, and about equally positive and negative for Santa Monica, San Pedro, Oceanside, and San Diego areas. Santa Barbara Shelf Is the most Interesting. Samples occur throughout the diagram, so that In toto the plot resembles the widely spread samples from non- deposltlonal areas (Fig. 67). Sediments from the Santa Clara prodelta, which Is modern, are found in the lover right comer, as would be expected from conclusions drawn from Figure 66. Also samples from the nearshore environ ment ocour In the negative and lower part. Very fine grained mud samples are found In part of the diagram where skewness values are mostly positive and between 1.0 and 3.0, much different than for the prodelta. Between pro- PHI STANDARD DEVIATION 1 . 0 2.0 •AN PEDRO ' OCEANSIDE NEARSHOR^ 1 1 1 1 1 1 1 1 • -4 -2 O C 4 S • PHI SKEWNESS Figure 66— Sorting (Phi. Standard Deviation) va. Skewness » SKEWNESS VS. SORTING SANTA BARBARA SHELF * CARPINTERIA SHELF RISE o NEARSHORE • OTHER Figure 67 * 6 -4 -2 LARA PROOELT O 00 a> FIRST PHI SKEWNESS e *t PHI STANDARD DEVIATION 149 delta and mud deposit on the graph are points representing the Carpinterla sheIf-rise. Separation of these groups is complete— eaoh sedi mentary unit is plotted as a distinct area of the graph, and it should be remembered that this graph does not con tain median diameter or any other measure of central tendency of sediment grain size. Also three of the groups (Las Pitas mud, Carpinterla shelf-rlse, and Santa Clara prodelta) foxm diagonal plots suggesting a family of parallel interrelationships between sorting and skewness of each sediment unit. The units are distinct both in grain size and in size configuration; a difference in origin might explain such a marked graphical differentia tion. SUMMARY Average values of sediment parameters for the main land shelf (Table 3) can be compared to average values published by Emery (1954). TABLE 3 Average Values of Sediment Parameters Median diameter 0.060 mm A measurement of sediment sorting widely used In the paBt, the Trask sorting coefficient, of the sediment samples distributed relatively uniformly throughout the mainland shelf averaged 1.6. This is equal to Emery's 1.6 for mainland shelf sediments. Average value of standard deviation for the samples is 1.00 phi-units. The average median diameter of this study (0.060 mm) is less than half the value published by Emery (0.140 mm). Most of finery's samples to determine average values were taken from the Bhelf off San Diego, which has been shown to be coarser than average for the mainland shelf because of its relict origin. This illustrates the danger of assuming that Phi standard deviation 1.00 phl-unltB PlrBt phi skewness Second phi skewness Sorting coefficient 0.20 1,16 1.6 151 sediment characteristics of one area represent another. A sorting coefficient of 1.6 apparently is typical of the mainland shelf, but 0.060 mm 1b a better approximation of average median diameter. The naturally-occurring deposits of the southern California mainland shelf, their subdivisions, and major characteristics of each are shown in Table 4. Triangular diagrams of textural composition of each deposit are shown in Figure 68. The purpose of sedimentologlcal studies is not only to determine and map the areal distribution of sediments on the B e a floor, but also to learn of the processes that caused bottom materials to be in their present locations and to understand what changes in sediments are likely to occur in the future. Origin, or geneBls, of sedlmentB is an important and desired outgrowth of such studies. The need of this study is Illustrated by a dis cussion of the concept of marine wave base by Dietz (1963). Knowledge of areal distribution of sediments led to the conclusion that the mainland shelf is not a profile of equilibrium but is a feature cut by a fluctuating surf- base. Only the nearshore lens of sand has a profile of equilibrium and outer part of the shelf contains relict sedlmentB, indicating they are above wave-base of erosion. Exceptions to this generalization may be the Santa Clara prodelta and part of the Ooeanslde Shelf, both of which Pt.Arguello to Pt«Conception Seaward decrease in grain size A Pt. Conception Harrow-theIf Complex Pt•Conception to Gavlota Sheet of sand and silty sand 1 Gavlota to Goleta Complex sediment distribution related to bedrock geology 1 Ooleta to Santa Barbara Pt« Seaward decrease in grain site 1 Ooeanalde Narrow-shelf Complex Huntington Beach to Carlsbad Seaward decrease in grain size i Carlsbad to La Jolla Sheet of sand and silty sand La Jolla to Point Lama Seaward decrease in grain size Santa Barbara Shelf Complex Carpinterla SheIf-rise Elongate topographic rise of authlgenlo ana organlo sediments Las Pitas Shelf-basin Silt Santa Clara Prodelta Progression of sand to silt from mouth of Santa Clara River I Santa Monica Shelf Complex Inner Shelf Seaward decrease in grain size § 09 Central Plateau Coarse rock fragments. authlgenle minerals, and organic debris 8 San Pedro Shelf Complex Harbor within brealcwater Silt B Central and outer bay Sheet of fine sand, central region of rook fragments San Diego Shelf Complex Inner Shelf Fins gray sand and silty sand, seaward decrease in grain else Outer Shelf Medium to coarse red and brown sand TABLE 4 LOCATIOHS AID MAJOR FEATURES OF MiTWim SHELF DEPOSITS 165 PT. CONCEPTION NARROW-SHELF COMPLEX LAS PITAS MUD DEPOSIT CARPINTERLA SHELF-RISE DEPOSIT SANTA CLARA PROOCLTA DEPOSIT * 4 * Kl SANTA MONICA SHELF COMPLEX SAN PEDRO SICLF COMPLEX OCEAN 90E NANNOW-3HCLF DCPOSTT SAN DIEGO SHELF COMPLEX fCARSHOK ENVIRONME NT MTKIM KNOTt ntCOUtNCr Of OCCUMCNCC PC* »% COMPOtlTnML TMDM.I S E D IM E N T D E P O S IT S OF THE MAINLAND SH E LF Figur* 68 154 have decreasing grain size gradation to the shelf-break. Profiles of equilibrium may exist In these areas. An accomplishment of this study Is the determina tion of Bediment origin on the mainland Bhelf. For the three better-known regions, Emery (1952, I960, and 1961) devised a classification of sediment origin based partly on time (ancient or modern), partly on process of forma tion (organic or chemical precipitation), and partly on mechanical and chemical breakdown of submarine bedrock. An observation of major importance from this classifica tion was that only modern detrltal sediments (whloh are materials presently being supplied from nearby rivers, beaches, or sea cliffs) show relatively simple gradation from coarse to fine grains in a seaward direction. Such a characteristic is the result of distributive capa bilities of the ocean at its present level. Sediments in equilibrium with their environment show such a gradation, except under unusual conditions. A refinement of Emery's classification of detrltal, residual, relict, authigenic, and organic sediments in volves two basic factors: (1) method of accumulation of pprtioles, and (2) particle formation. To indicate both processes and to avoid introduction of new and oumbersome terminology, a binomial classification is useful. The first word in the classification, used in a descriptive or secondary sense, is concerned with the method or agent of 155 particle formation. There are three possibilities: (1) clastic, particles composed of Igneous and metamorphic minerals, rock fragments, or clay minerals, even though they came last from sedimentary rocks, (2) authlgenlc. chemical preoipltates that form on the sea floor, such as glauconite and phosphorite, and (3) organic, particles formed by animals, such as shells, tests, pellets, and skeletons. The second word In the classification is the more Important, for It describes the most recent prooess— the method of accumulating particles that form the sedi mentary deposit. The particles may be (1) detrltal. com ing from land via rivers, beaches, and cliffb and being distributed by the modem ocean according to its sedi mentary processes; others may be (2) relict, the result of distribution under conditions that existed in the past. The particles may be transitional between the two previously mentioned situations; that is, they are lag deposits of a transgressive sea. Suoh deposits are, In a sense, also relict, but are classified as (3) transgres- slve to convey additional information about them. A final category is rock on the sea floor that undergoes meohanlcal and ohemical breakdown by the waters of the ocean, but the resulting particleb remain in close proximity to the rocks themselves. These sediments are (4) residual. Although other sediment types exist, they are of little importance on the mainland shelf of southern California. The soheme 156 of this binomial classification is presented on Table 5* Classification of sediments for a given area ac cording to this scheme is possible only when detailed knowledge of the sediments, their areal distribution, and their mlneralogical composition is known. Such informa tion is now available for the southern California main land shelf. Areal distribution of genetic sediment types is shown in Figure 69. The classification is based upon Information gained from analyses of 1389 samples. A measure of grain size central tendency Is probably the best single parameter to use in recognition of sediment origin, but other criteria are sediment type, sorting, skewness, color, mlneralogical content, bottom topography, bedrock structure, and combinations of these factors. Where the mainland shelf is narrow (less than 6 miles), clastic detrltal materials occur as far seaward as the 300-foot depth contour (Fig. 69). This includes part of Point Conception Shelf and most of Oceanside Shelf. Detrltal materials blanket the shelf between La Jolla and Point Loma, but are mixed with shell material. Regions of detrltal sediments are characterized by a gradual seaward transition of coarse to fine sediment, Buoh as occurs from Point Arguello to Point Conception, Goleta to Gavlota, and Newport to Carlsbad. The nearshore environment is mostly detrltal in origin. Inner parts of wide-shelf segments also consist of Method of Sediment Accumulation Modern Ocean Anolent Ocean Transgresslve Sea Submarine Rock c 0 P « o rl ■P 0 Clastic Clastic Clastic Clastic E £ 9 O Detrltal Relict Transgresslve Residual • rH O ri «P 1 H o 4* B Authlgenlc Authlgenlc Authlgenlc Authlgenlc 6 0 4 9 © < t o Detrltal Relict Transgresslve Residual * 4 o 0 0 0 -p • e • to o H A Organic Organic Organic Organic o o £ Detrltal Relict Transgresslve Residual TABLE 5 CLASSIFICATIOI OF SEDIMKHT ORIQIH ot V —cki O tO lK D C K )S IT 1 a*i»< «ti«t Xt»l GENETIC UNITS Figure 69 159 detrltal sediments. The area behind the breakwater of San Pedro Bay* most of Santa Monica Shelf except the oentral plateau* the inner part of San Biego Shelf* and the Santa Clara prodelta are composed of detrltal materials. The Las Pitas and deposit is probably detrltal* representing an extension of the Santa Clara prodelta deposit. Only modem detrltal materials are undergoing active trans portation under present environmental conditions. The probable direction of sediment transport is indicated by arrows in Figure 69. Residual sediments* products of weathering and erosion of submarine bedrock, occur on the shelf between Gavlota and Goleta and on the surface of Carpinterla shelf-rlse. The Beaward part of this rise consists of authlgenlc residual sediments* mostly reworked glauconite. Large areas of residual sedlmentB occur in San Pedro Bay* and the central plateau of Santa Monica Bay Is a mixed sediment* at least partly residual in origin. Relict sediments lnolude red sands near San Blego* Huntington Beach* and In Santa Monica Bay. Probably of more recent origin than the red sand are transgresslve olive-green or gray sediments that were distributed by advancing surf action as sea level rose from its former low stand to its present level. Such transgresslve sedi ments* which apparently are not yet covered by modem 160 detrltal materials, occur off San Diego, north of Point La Jolla, and between Point Conception and Gavlota. Usually the amount and proximity of sediment supply and a transporting agent determine the areal extent of detrltal materials. Where sediment supply Is low or absent, relict and residual sedlmentB remain on the sur face unless covered by organic and authlgenlc materials. All will eventually be covered when the detrltal blanket extends seaward as sufficient material Is carried from land to sea. Sediments of the mainland shelf are at the present In the process of adjusting to a new set of environmental conditions, namely the existing sea level. REFERENCES REFERENCES Allan Bancook Foundation, 1958, A field and laboratory manual of ooeanographlc procedures (preliminary version); University of Southern California, Los Angeles, 96 pp. Diets, R. S., 1963* Wave-base, marine profile of equilibrium, and wave-built terraces: a critical appraisal; Geol. Soc. America Bull., v. 74, pp. 971-990. Durham, F. E., 1955* In Quantatlve survey of the benthos of San Pedro Basin, southern California; Allan Han cock Expeditions, v. 19* no. 1, pp. 152-153* Emery, K. 0., 1938, Rapid method of mechanical analysis of sands; Jour. Sed. Petrology, v. 8, pp. 105-111. , 1952, Continental shelf sediments of southern California; Geol. Soc. America Bull., v. 63, pp. 1105- 1108. ______ , 1954, Some characteristics of southern California sediments; Jour. Sed. Petrology, v. 24, pp. 50-59. ______ , 1958, Shallow submerged marine terraces of southern California; Geol. Soc. America Bull., v. 69, PP. 39-60. ______ , I960, The Sea Off Southern California; John Wiley and Sons, New York, 366 pp. . 1961, Submerged marine terraoes and sediments, In Pacific X8lan£ Terraces: Eustatlo?, edited by R. J. Russell; Gebruder Borntraeger, Berlln- Nikolassee, 106 pp. ______ , Butcher, W. S., Gould, H. R«, and Shepard, F. P., 1952, Submarine geology off San Diego, California; Jour. Geology, v. 60, pp. 511-548. f l . and Hulsemann, J., 1963, Submarine canyons of southern California; Allan Hancock Pacific Expedi tions, v. 27, pp. 1-80. Folk, R. L., and Ward, W. C., 1957, BrazoB River bar: a study in the significance of grain size parameters; Jour. Sed. Petrology, v. 27, pp. 3-26. 163 Hamilton, E. L., 1956, Sunken islands of the Mid-Pacific Mountains; Geol* Soc. America, Memoir 64, 97 pp. Inman, D. L*, 1952, Measures for describing the size distribution of sediments; Jour* Sed. Petrology, v. 22, pp. 125-145. . 1953* lreal and seasonal variations in beach and nearshore sediments of La Jolla, California; Dept* of Army, Corps of Engineers, Beach Erosion Board, Teoh* Memo* 39* 82 pp. Krumbein, W* C** 1934, Size frequency distributions of sediments; Jour. Sed* Petrology, v* 4, pp. 65-77* . and PettiJohn, P. J., 1938, Manual of Sedi mentary Petrography; Appleton-Oentury-Orofts, Inc., New York, 549 pp. McManus, D* A., 1963* A criticism of certain usage of the phi-notation; Jour. Sed. Petrology, v. 44, pp. 670- 674. Moore, D. G., 1951* Marine geology of San Pedro Shelf; unpublished Master's thesis, University of Southern California, 87 pp. ______ , 1954, Submarine geology of San Pedro Shelf; Jour. Sed. Petrology, v. 24, pp. 162-181. ______ , I960, AcouBtlc-reflectlon studies of the con tinental shelf and slope off southern California; Geol. Soc. America Bull., v. 71* pp. 1121-1136. Pratt, W. L., 1962, The origin and distribution of glauconite from the sea floor off California and Baja California; Unpublished dissertation, University of Southern California, 285 PP. Shepard, F. P., 1948, Submarine Geology; Harper and Brothers, New York, 348 pp. ______ , and Emery, K. 0«, 1941, Submarine topography off the California coast; Geol. Soc. America, Special Paper 31* 171 pp. ______ « and Macdonald, G. A., 1938, SedimentB of Santa Monica Bay, California; Amer. Assoc. Petroleum Geologists Bull., v. 22, pp. 201-216. 164 Stevenson* R. E.* Conrey* B. L., and Gorsline* D. S., 1954* The inshore survey of the Los Angeles Harbor approach area* California; report to U. S. Navy Hydrographic Offloe from Geology Dept.* University of Southern California* Los Angeles, 177 pp. Terry, H. D., Keesling* S. A.* and Uohupi* S.* 1956* Sub marine geology of Santa Honloa Bay, California; report to Hyperion Engineers* Inc.* from Geology Dept.* University of Southern California, Los Angeles* 177 pp. _______, and Stevenson, R. E.» 1957» Hiororelief of the Santa Honloa Shelf, California; Geol. Soo. America Bull.* v. 68, pp. 125-128. Thomas, £• G., Marllave, E. 0., James, L. B., and Bean, R. T., 1954, Geology and hydrology of Ventura County* in Jahns* R. H.* Editor. Geology of Southern Cali fornia; California Div. Mines Bull. 170, Chapter 6. Uchupl, E., 1961a* Marine geology of the southern Cali fornia mainland Bhelf: part 2* ohemical properties of Bediments* in Oceanography of the Mainland Shelf of Southern California; report submitted to Cali fornia State Water Pollution Control Board by Allan Hancock Foundation, University of Southern California. . 1961b* Submarine geology of the Santa Rosa-Cortes ridge; Jour. Sed. Petrology* v. 31* pp. 534-545. Wentworth, C. K., 1922, A scale of grade and class terms for clastic sediments; Jour. Geology, v. 30* pp. 377- 392. Wlmberley* S., 1955* Marine sediments north of Scrlpps submarine canyon, La Jolla* California; Jour. Sed. Petrology, v. 25, pp. 24-37. _______, 1963, Sediments of the mainland shelf near Santa Barbara, California, %n Essays in Marine Geology in Honor of K. 0. Emery, edited by T. 0. Clements; University of Southern California, pp. 3&L-201. APPENDIX SI MD PSD FPS SPS SO LAI LOW WD SSPLAHATZOV OF SUBQIS SI Sanpla luabar ID Median Dianatar In Milllnatara PSD phi Standard Dariation FPS Flrat Phi Skavnaaa SPS Saoond Phi Shinnaaa SO Sorting Coafflolant of Trask LAI Latltnda in Dagraaa* Minutaa, Saoonds LOW Longitnda in Dagraas, Mlxratas* Saeonda ■D Vatar Dapth in Faat 166 167 b » 8 8 8 2 8 * 8 3 8 8 3 * 8 * 3 % % “ s 5 s * s I S I * s * s * s I I ' 8 s n u u u u C QOAttOOOIIOlOlO^iQ OH*C4lQ«0Oio» OtlOOlv5 ! ! * • • • * « • • • • • H H H H H H H H H H H s s 3 s s 5 s s n * n 8 j 91 H H H • • • • • C4 8 • • H A A A 3 8 ?) IO \ '* 8 ?• H 8 £ 3 O r- % . d 9 <« 8 | $ ■ 2 8 A * 8 A £ A w 8 8 8 W A IO S A 0* A 3 A 8 A V H V H A H V H 8 A A A A O A H V • W • 8 A 9 a 8 A 8 A w A • V • V • S 8 S £ 8 8 8 ? S g S 8 S S 8 8 a 3 5 I i I I • - • Ot- HAQ AM B B- * ; n s § j s j 8 • • • • ••• •• •• * A ■ftiAToATT a O f i i T O o T C 88*1 K* 9 0 * 9 9 * 690* 6 9 /.* 168 s § 8 s 3 8 M H 9 s i 9 8 s I • '■ 8 'B <S B 'B <8 'B >B '8 'B 'B 1 8 8 3 8 3 3 8 8 8 8 8 3 3 i l H i i l i l i i l H i a a a a s a s a a a a a a a 00 • • • • M H H H e s 8 a 8 A • * • • CO H I H S 3 m 3 3 m 3 IO S' 10 «* 5 O < ? 8 8 8 8 8 Si 3 8 H r4 H H ©» o 8 3 3 H 02 IO • 02 • oS o- I O <0 01 3 8 8 1 S* 1 8 8 8 8 iH VO 8 H H H 2 8 3 Ot H 01 o • 2 • 8 • • • • • • • • • I I P S D H 0 • 01 8 • 01 0- • 1 * 0 3 01 V0 • 8 • e- IO • 8 • 8 • IO 4i • H • 8 8 3 • a 2 o 8 O 01 8 i 0- IO o IO 3 | 01 8 1 2 oa 01 IO o i 3 I # • • 9 • • • • • • • • • • s 8 3 H § M • 3 I 10 5 3 e- * r* 10 0* 41 3 3 3 e* 4i i t g e* 41 41 41 4776 .047 ,49 .82 4.3 2 1 .2 1 3 3 ° 2 6 '0 0 " H 7 ° 4 1 * 1 0 * 4 7 7 6 *020 3 * 6 1 3 3 ° 2 6 * 0 0 ” H 7 ° 4 3 ’ 3 0 * 169 s 3 120 X 518 270 165 8 268 3 3 S 168 288 264 1 168 8 • B 09 V O *> p • B 1 0 * to ' B IO 09 to I B 3 q b ' B 8 0 0 ’8 a S ■ m IO IO 8 B o 09 S % 09 s ■ 8 8 # 9 8 o I io S ' £ S i «• IO « * IO o a o 1 | 8 o I 1 | .* 1 | 8 X X X X A X X X X X X X X 2 X 3 a 9 9 09 <0 A s i 8 8 A 3 A a 0 a 09 a 9 A 8 a 0 - IO A 8 A • H • •H • H M w H V l- l r t W 09 W i- l V H 09 V H V H V r t w rt W H 9 A O ? a s A X A 8 £ 8 A <0 H 3 a a 0k X A 8 * 3 A s a V H • * V H V H V ♦ 1 W V 1 w r t V H 01 W r t 9 •O o Ok IO 3 Ok <0 8 8 8 e * o 8 2 8 rt IO 8 3 a • • • • • • • • • i • * • • • • • • • • • • • • ' ' H * * * i ! i S I I 3 I s 5 3 I S § i I I • • • • • • • • • • • • • f c s g a x s g s a g a a s 5 5 3 5 3 3 5 9 3 3 3 9 9 s & 3 3 170 e 3 s 8 8 8 * 8 2 8 8 8 3 168 168 3 3 3 8 | * * 3 M3 M l 8 'B 8 * * * ! § o 1 | 3 O a o 1 I I 1 1 o h o b - H O M s o 9 § o a § 0 k a 0 k a 2 3 0 k a 3 B 0 0 1 8 o A 'B 8 1 •m a 1 1 | 3 1 M3 r t M» * M l IO 3 1 g * g I O ? ?■ g M3 g * f 0 1 ? I 1 I 8 O 1 2 3 8 X 2 2 X X 2 2 2 2 2 o M l a 0 0 ) 0 ) 3 O k A 3 A < 0 I O 0 IO 0 0 0 r t 1 0 A 2 A < 0 r t A I O A H A 0 0 A V ] rt H H w r t w H r t H A V H V A V H V H V H £ + 6 * o IO 0 0 IO e » * O k 3 5 £ 3 M3 I O b * 0 1 K 0 1 • • • 0 0 • H • H • • r t * • 0 0 • 0 0 • S P 3 8 b - I O 1 0 IO 0 0 2 S CO Oft b - M l O k o k 8 3 b * r t e • • • • • • • • • • • • • >-l H • • 8 s s § 8 3 3 8 8 8 8 8 8 0 8 3 8 8 8 8 H H H 00 rt 00 a 3 3 S 5 I i 5 § 5 I 3 i g I i 1 • • • • • • • • • • • • m «8 t t Q H N ^ l O t O^a Mlh QO kOO l s i s i s i M i s s l s i s 171 e | S 8 S J S S S $ 8 S S | S a 8 ■ ' B ‘ S <8 B <B a 8 '■ B B 'B B -8 • 2 S 8 8 $ 2 2 8 3 S 3 8 8 8 5 3 8 3 3 3 8 3 5 3 3 8 8 9 5 2 8 3 3 d d a d a a s d a s s a a d d s „ % "9 % I % % I I S I ft ‘ 8 5 8 I 8 3 # £ i f £ - 5 5 8 2 S 3 3 8 5 3 0 8 3 8 8 8 8 8 3 8 3 8 3 8 8 8 3 CO • • • 8 8 5 3 8 3 8 3 3 2 2 3 3 s • • A 01 I • * t « • io h a io 01 w • •• ••• •• to o i a a oa a * 3 3 3 3 8 8 4 3 8 3 3 3 8 3 3 3 £ ( • • • • • • • • • ( • « * • • • * a a a a H U S ? s 8 8 Sj S H S. ? S 8 01 H H s 1 1 ». H I ? s 5 s 5 a ? 3 I I • • • • • • • • • • • * # * « * m o a H « Q «> C» 5 2 i I 3 3 to <0 8 £ S t- £ Si 9 8 9 9 8 8 9 172 m IO o <» 10 * m m 8 8 9 o I 1 # 8 10 A 3 3 O 9 a s s A A ¥ > V A V V H f-t 8 6* S • .79 •44 o s s s g s s s s g s s s & s a s s 09 • • • • • • • • • . • • * • • • ‘ H H H H H H H H H r H i - t H 2 S 3 ? 9 8 8 S S S 8 8 S 8 8 3 3 09 I 01 • • M oo m s g f c 5 f c 9 ? l « o ® o » < o ® 9 0 a i ® i O H Ot 09 173 a g * 8 I § § B I I I I 8 8 I % * gaaaassaai d s s s a s a a ■ '■ • ■ B M B B 8 8 8 8 8 0 8 S a i j i n n i i s s S f s s S & • • • • • • • « H H H H H H H H S O H A H A b» A 0» 10 3 « o H Oi • • • » • • • 00 I A A A H S a a ® co 10 t- e- A O rt A H 09 A ... .. . . § H 8 3 1 1 3 8 3 8 3 3 s OVI | B 8 % J . A A t . A A 3 st s a 33a 3 ° 3 0 0 3 1 s % % ° 3 3 a A A A 8 8 A A H A £ S A 3 A 8 A H A H A A H A H A H A A A 8 • H 8 • A A A O A • • H 8 • H 3 • 3 • H A • 9 8 8 8 9 8 8 8 • ••• •• •• g A A rt O IO *• A A A A t» A A A • • • • » • • « S « o ) S 3 S • ••• •••• rt rt A H A M a S 2 2 i I I S I I i I § I I I i • • • • • • • • • • • • • ■ i M i M i S i i l i S S O A * A A 174 e 03 8 168 IO Hi <0 10 3 I 174 108 2 8 008 870 & 174 2 9 3 ■ 10 IO 1 B 8 I S ?) rH 'B « 01 « 01 1 1 'h> 10 H* 3} % • B 2 to J J | J ? A ? t f t o 1 ? Ok * # ? ? ! 2 I 2 a a a a a a a a a a a a a 3 a a * t- 10 | % •9 1 B 2 8 B 8 ’ t> o 8 • B 8 r H 8 3 1 S3 t o i Hi 0) o ? 1 1 i 1 1 H 1* 3 O * * # * e - p 2 * n * 10 ** h . n o> 2 2 2 2 2 2 2 S •0 10 2 2 s A 3 a 8 A s s A A S 0 s A 2 A So a 09 a 8 a 9 A 2 a a 0 IO rH a V 0) w H V H rH H IO V H w H H V 01 V 01 W r H V H H H H 9 • 8 • 1 IO H • H f f l n 09 W • • H H w to • (O r H • 01 2 • rt 8 • H H 0 • 1 3 • 2 • % H 2 • 3 H Hi 01 • 8 • • • • • • • * • • • • • • * • M rH H ca H H H H H s 2 I 8 § 3 3 2 I § ! 2 I 8 1 • • H •3 175 e *• 09 a £ 5 5 o» • • • Ml H 180 3 888 876 8 174 to n 186 90 108 09 3 3 09 f) oi ’! % s O H S ' B IO o 1 i | s •8 3 3 O 3 O 1 t* «* 1 I1 ?■ s ' <? $ a a a a a a a a a a a a 3 o 09 3 8 to to 3 IO 8 8 8 8 8 i o # i ? 1 1 1 1 ,? H <P H .P 1 3 3 3 3 3 3 to 10 3 3 8 3 3 a H 01 0 3 0 IO 01 0 < 0 H A IO to A 0 01 A H H O 09 A A S A 3 A s A H H H H V H 01 V H w V H r t W H w H V H 3 • 10 •85 •67 8.79 to o • 09 3 • H 0 • 1 3 3 • • • 3 • 1 3 • a 4 • 8 3 n S 8 ! i 2 8 S $ S S S 3 • • • • • • • • • • » • • • • • • • I I • § 8 8 8 n 8 8 8 83 8 n !! 2 • • * • • • • • • • • • • • • Ctt M 09 i i i l l l i i i i i l S i t i 1*14 -*45 1.57 5S°35»12" U 7°59*58* 158 176 ■ ■■ * <■ -m -b <m '■ ■ *■ -o a b 8 « M l O M ) H ) b l O O O « O Q « 9 M O l O « l f } O O O I D l S S s s s s s s a a s s a s a „ 8 I 3! % % 8 % “8 *8 % "a % S? o S S S 8 8 S 3 S 8 5 3 8 8 0) • • • • • • • •• • •• « rtHHHH HHH HH HHH 5 S ? U 8 f s u s ; s • • •• ••• !• •• « • M H • HH • c o w S o ft • r IO 10 H <0 • • I s : : n s § 5 3 5 8 8 3 3 8 8 8 5 8 8 i i s i i i i s i i i s s i • • • • • • • • • • 6 1 6 6 * 0 6 5 1 * 4 6 * 7 6 £ * 6 1 1 * 5 4 64°23'06* U 9°40’4 0 " 126 6 1 6 7 * 0 6 8 5 * 0 6 * 6 8 . 8 6 5 .28 54°B 1» 40" 119°40'40" 177 6 1 6 8 .0 9 6 1.59 .7 6 2.06 1 * 6 0 54°20»20* 119°40'40" 216 177 ID 900 804 8 891 864 106 198 189 180 04 a 8 04 840 870 3 3 *9 m A A % 04 A | ? O k a f. a S « . I ? e* f i l l ! a 3 a a a a a a H H H I H a a a a a C4 • 8 A M 1 m 8 8 A A A A 'B 8 1 1 'B a s S j 3 B 9 3 S o 04 04 o 8 O H O a o 1 I 04 ? H J ? ^B H il o A i ! ? A » S ? 8 A A A A 8 8 04 A 04 A C4 A 04 A 01 A A A 04 A A A 8 8 o M l a a 8 + e** H e - A 8 t- H A 8 A 8 A 3 8 A 0 4 8 8 a 0- ri w « 04 A H H A V H W H 9 H # # H • H • H # rt • H • rt 2 At • S O A 04 • 3 • A A • g • 3 • 60* A A • <0 04 • •16 A A • 8 • 3 g • 8 • A H rt i • ¥ 04 A A * 1 0 FPS to H • 8 • * A • 09* 8 • 8 • o 0 A • O • 3 • 1 8 • 8 • 3 3 • g • g 8 3 $ 5 8 9 8 51!! S t 8 8 8 9 H A H 01 aSS|i3SIS5l3l!S? • • • • • • • • • • • • • • • 5 S S S ? S 5 * S S 8 S “ ‘ S g g g g i o g g g S g S 55 « ib i i 1 1 6 2 0 6 0046 069 .67 2 .4 6 1 * 1 9 5 3 ° 2 2 » 1 6 " U 7 ° 5 7 » 6 6 t 1 6 8 § § 1 § s « ® 2 3 3 3 8 8 8 8 8 8 b 3 8 8 " • 0 0 9 • 0 0 7 • § • § • g • 0 5 0 H t • £ • § • 0 5 7 • 0 6 7 • g o • O P • § • g • o 8 M 9 to • • w • 10 • 10 • • M • • • • H • to • 10 • H # # g o 09 •0 o 8 Ol H 3 3 O <0 •4 g 3 -a 01 3 s 8 • g • to H • 8 • 1 9 • § • to C O • g • g • to -4 • g • 0 0 • to o • £ • 8 • 7 8 • g £ A to A 3 A A H A A to M A M H H to g to H H 8 10 to £ 8 8 8 « o 3 • H O # to o # M C O • Ok H • to 01 to A C O A H A to A C O A H A to A H • H H to to to M H g to S 2 3 to O D to ■0 to «0 W C O Ol • C O * # g • 3 • -4 01 8 • O l H # to -4 2 . % 2 . % 1 % 2 . « I g o g o C O #> o 2 2e 20 2 e £ 8 8 g g g 8 to to to H 1 £ £ S g g 8 H O l S ' to o S ' i 4 IS ° . 8 S> £ C O ■ - 8 s> 10 O l s H CO s> g s. O S CO * g S' i S' 8 s © O l s 8 B O e e p t i i s p p p c e f c s c t j E t : 8 S 3 8 g s g g g g £ £ £ s £ 8 i A i i i i i i i i i i A i A i % <o 09 to o M 8 I * Ok -4 «0 •i 3 8 B S to t o <0 g 841 179 «D 2 i i 901 81 01 a 177 § § 868 s J a a 189 891 3 B a 1 s B IO rt 8 IO o >8 8 u» Hi •B 8 ’B o M '8 8 1 8 ‘ j 8 8 B a o 1 a U> 9 s p ?■ p 1 f 0» 4^ 1 4^ H P 4A H p 4^ I I I a I 4^ 09 d 09 a v« H H d a rH W* a A A a H a rt 08 a a a a d a B 8 01 n •» B io 10 | U3 01 2 2 •8 8 •B s m ■B 8 • f t IO § % *» ! A a •» 3 3 Hi 10 s' HI 10 «0 S' * 10 i a M a H •0 # Hi 10 p 8 1 Hi *3 « rH °Hi •0 P 8 1 10 P 8 1 P Hi n a °8 P 8 O rf% (0 t* • 8 A 01 V) A C- GO A s a a * 8 A 8 a 3 A 8 A 8 A 10 a a s s a a a a 8 a 01 oa 01 01 01 a 01 01 01 N A H V ■H oa a a H a a s rH 01 0 0 a a 0 rH a 0 a 10 a 8 a 8 a 8 0 s a (» IO A a a 8 a 8 8 a 8 a s OQ V V a a V A H V • a a # FPS e- rt • 01 •0 • rt IO • 8 • $ • ID H • 8 • S • • 8 • 8 • g • a • 8 • j • 3 • a IO • 180 e s s s s s s s s a a s s s s s s s P H O t H 61 O O 3 rl H 0» O CO P o h io oa t- 08 • • • • oa H H H s « $ 3 3 o a •0 A • « ■B 8 8 8 8 s 8 % & & 3 3 3 I m 3 1 rt P rt a % 1 § 8 A IO f i - a rt P A o a V rt P rt 8 a 8 A 8 a P V P rt • • • • H H rt H c » O P P P P 0 i a > M O I O t ^ H O M l O p > B 3 | 2 's 1 a s & P «* o P o a & ! ! rt ? P I • 3 r t r t 3 3 3 3 3 rt m B s « * 5 '«> O m O P m 'B 8 ' B to rt s o ID g 3 O s* t* rt O P S ’ 8 8 8 8 8 8 8 0 01 £ B - 80 8 0 8 rt £ 8 A A 3 A rt rt rt o a P rt P « P rt 3 0 IO A IO m a p 0 8 a P o a a rt rt A S A rt ? o a P p rt P rt o a 8 • ? • p • • 3 • S • 8 • 3 • I 3 n ; 5 j s a ; i n s s is • • • • • • • • • • • • • • • • 0» rt Oi rt rt H H rt rt rt rt a I 5 I 8 I i I ! I 8 I i 3 3 i 3 • •• • •• • • • • • • • • P oa I 3 S 8 < 5 S 8 8 8 3 8 8 8 3 Iliii 181 3 s § § <0 t* ot a O a 8 O 0- ot 8 g Ot 3 8 8 500 234 ■ 9 8 ■ m to DO « 8 ’ ■ o ot fi ot ■ 8 ■ m 8 8 '■ 8 'fa 01 1 1 fa a o • s * to | 8 % . 8 t- ? I 8 0; ! i a %t { « 3 d 3 rl H d 3 d d d d d d d 3 d fa * a 8 to H A 8 oa IO 1 "3 >■ 8 'fa to $ * £ 8 a o a o a o 1 8 O tb ? Ot o | H g> £ s o s o 8 o 8 8 3! to to oa to s n to 8 8 8 A oa 8 oa oa 01 oa ot oa 0 • H to 10 • rl 1.91 e* ■ ot • rH •o oa • .H 1.20 8 • iH ? • rH g • Ot 3 • «H 01 rl • H 8 • H 3 • O f t 8 • rl 1*21 s oa a* oa oa oa g ot Sa oa oa oa • oa oa oa • oa P e- e- « to • • ot g n n u s n 8 01 « u u u n u u « u u u • « • • • • • • a 3 i 3 i § I I I I S § 3 I § I ! t - 8 • § • S o • 8 O • 8 2 8 8 8 8 8 8 I I • • • • u u u 8 8 8 8 8 8 182 8 1 8 3 8 * * 3 3 3 2 3 3 3 3 2 3 * \ I I % 3 s % ' 8 % ' 8 s s " s ’ a a 1 8 8 8 8 8 8 8 8 8 8 8 8 8 8 2 8 3 3 3 3 3 ; 3 « 3 I O 8 o % '% H « H • » rH I O 8 O k I O € to 8 O k 3 3 d 8 8 8 8 O I r l «■ 3 3 8 8 3 C O D O A 01 O i w H 8 A 3 A 8 a V w V r H < > 3 3 3 8 8 3 3 3 8 3 8 3 3 3 3 8 « # • • • • • • • • • • • * • • • • H r H r H H O l r H O l O l H r H r H r H C t t r H r H l O j n 3 8 8 8 8 8 8 9 8 2 3 3 8 S 3 8 m • • • • • • • • • • • • • • « • *9 ^ H rH rH rH rH rH rH I rH g 8 3 3 8 8 8 8 8 9 3 8 8 8 8 6 3 * * • • * • • • • * • • • • • • • • PSD •66 O Ol t- *0 • • H S 8 S 8 8 8 S 8 8 • • • • • • » • • rH rH rH rH rH rl rH $ H 8 3 8 • • • H M s' § • 1 3 • • 1 1 1 1 1 3 1 1 ! • • • • • • • • • § • § § I • • • to e» CO g 8 8 8 8 i l l i l l i l l 1 3 3 3 185 8 IO H § § 3 8 H 3 Ot 8 • S r« O Ot 19 Ot H <« IO H s IO rt ■m 8 1 s 3 H 19 8 8 8 6 S 3 3 3 3 3 3 3 C4 8 8 8 8 H 8 s 2 o ot 8 8 8 3 & 19 n 2 8 « n * 19 8 8 8 o (A 3 a 8 A 8 a 8 a 8 8 8 wj V H 01 V H V H • rt # Ot • H f f i oa rt 01 • s • 9 • rt 8 • 19 01 • 19 t- • * tO • 8 i 2 3 3 1 • a o t a 5 1 * > • I O * • * o t ' o » r t 8 H 8 8 8 8 8 i d 3 a a r t C D 3 3 3 o » a 2 8 ( 9 r H 1 & 1 * 1 93 8 8 8 8 8 8 2 8 8 * 1 98 8 8 8 < 0 1 9 0 3 9 0 » O t A 8 A 8 a a a s H r tr tH H V r t V H # r t 1 9 0 » • 8 • H 8 • 8 r t 3 • O t a • o t 8 • r t s S 3 3 2 3 ft & a e! 8[8 a 9 8 8 s • ■ • 1 1 ■ ■ * i 1 i 11 ! 1 1 ! 1 1 1 1 11 8 .1 4 1 * 8 1 5 4 0 5 * 1 8 " 1 1 9 09*50” 184 1 2 3 3 8 to to 1 2 0 0 1 1 7 3 o* to 0 1 1 9 6 1 6 6 1 0 2 1 9 6 3 as H t 2 4 0 S 0 0 1 1 0 to m* us o r t 8 to r t O e* r t e* to 3 8 01 us O l U S us * O r t O A 3 o 3 o A 1 A 3 O A 3 o A s o us M r t 0 1 CO a ?» S' s 3 Is 3 o wo r - l rt w 3 rt rt rt rt VI H rt r t rH U6 3 QJ rt rt V a 3 a a a 3 3 us us 1 ! 3 to 01 8 8 O U S 0 * O o U S 8 O U S U S 3 o U S to 3 o 8 3 O U S us 3 ? us o % US U) 0) o u s O io 10 01 o- P ° o o * <# 10 10 a> o o 10 us o % (0 o o rt US US to 5* 3 O ^ ^ H* 10 U S 1 0 10 3 8 f c - 09 O o co 8 co a > oa oa to 10 01 • • 00 10 ot o • • 8 • 8 • t- rt • a • to rt • O * a t • to r t • 3 • to r t • Ot • to C O • to 0 1 • rt 0 1 iH H to 0 1 r t rt r t r t r t r t to to • S • 0 0 rt • a • 3 • 0 1 u s • 3 • •69 3 • t « * r t • .68 U S 0 1 • r H rt 0 1 0 1 1 0 1 U S 0 1 Ol us O tO H 1 to o • • at to 0 1 H O l O l O C - U S C Q H t O t o u s ^ ) o a o o 4 > o i t o 3 us at to * • • • 3 C $ < H a > C Q ^ l Q l 0 0 1 t ^ U S « 0 < 0 ’* G l O a > * ' * U S O U S O l rt 01 rt rH rH 9 s rt rt rt to o rt US • • • us CO at Ol Ol 01 us US us US US us 3 01 01 to us o o • • 00 a t 3 Ol us 3 ♦ c - o 3 01 o US o to a t o O rH H • • • _ u s c o a t o o i t Q u s t o o > < D a i c o u s * u s g S S S 8 S 3 8 3 2 3 S i s X S u s u s u s u s u S u s u s u s u s u s u s u s u s u s u s 6666 .076 * 4 8 -*04 .16 1.27 3 4 °2 4 » 3 5 " 1 1 9 ° 5 3 » 4 0 i l i l i i l l S I S S • • • • • • • • • S M I g l i l S S I S I S S S S •0 H H H H O l § i o i s o • • 4 • s g • 8 • 8 c n - a H • H • 1 0 • H • ct m • • • • • • IS U !! 3 S i S S 8 S S U S 3 1 • • • • • • • • • • • • n 8 J 5 8 S K 3 8 i i S 5 8 8 i a 3 ► • • • W O H C R Ol C O H a H a a * A H A I - * a H a H 1 a H A C O t a p s 8 • P 8 V P P 8 8 V 8 w 3 9 0 1 O l < D « 9 8 V 8 8 W S 3 o o • 0 H 1 0 1 0 A 1 0 M A C O ft H H a H t o A t o A H C O a 0 1 A H fn • 8 • 0 1 - a 8 V O k 9 s V 0 1 e w 8 9 0 1 o V 3 8 8 w < O i 8 w 0 0 1 V 8 9 O l H c 8 S t S t 8 8 8 8 0 1 » 8 8 8 8 8 8 8 0 1 O k if o t o i © H 5 o 8 o t o * > 1 0 & O o E O t o H O s t o O k O 8 o t o o g 8 8 8 H O l 8 H O l i 8 » 2 O l 0 0 1 8 8 i 8 8 6 9 9 ■ a- S< S> S' a> S' s- s S- s s s s s P p P P P p p H M H p p p H H p H H p * • O «D O •o % % * * <8 % * t 8 8 8 8 8 8 0 1 1 0 8 0 1 « > 8 s 8 8 8 8 8 8 8 i A * 4 £ 4 £ i £ £ W W. £ 4 8 s 4 H 4 . 4 H H i i i i i i ! i c i H ' 991 5681 *068 .50 ,11 8.67 1.83 3*>60’66* 117® 1 9 *80" 6619 6618 6617 « H 01 6616 8 5 8 e 6610 6606 6607 6609 9099 i I t • i • i • to s • I 8 • 2 01 • H 2 * M to OI • • • M O M S OI OI « (0 N • 8 to MD •068 •866 • • • • i • f » • • • • • i S S S S g S S S S S S f S S S B S 8 8 8 8 8 § h 8 2 2 *3 5 8 8 8 • • • • oi co 55 » to oi o oi 10 A A to 9 2 8 • 0 01 # 01 M M M A H M 8 to -3 to o 8 01 OI oi 01 % •* CO 0 % 6 s t 01 H 8 ft ft 8 a> a> a< a> P s 8 8 * ■i -s •8 8 8 8 M OI 8 8 8 8 ■ ' ■ a- a> 816 801 866 10 2 • • M H H • • • CO M M * M • CO O ■ 0 0 0 O to O * '■4 ^ ' «4 •* ! " J 'S g S ^ I i l s s s % s. % % s. s 1 1 i i i i i 4 i S S g S E 8 s I I I § s I 8 S I 9 98T 187 e 3 i a 1 0 8 IO * s 8 H 0 0 8 0 k 1 0 900 990 900 8 3 O k rt * 1 1 0 U > to B IO + 8 S a 8 U > •0 % -a 8 '8 8 * a 10 a •0 • * | 8 3- 1 s 3. 8 9. I ? 8 9. O k c j I ? B P ? a a a a 3 O 8 O d d d H rt a d d d d d d d d a d d ft* ■ 8 ■ 8 A t U > 0 1 « O & IO -a 8 a 3 a • a O 0 9 1 3. * 0 O 2 1 1 8 3 S $ 0 0 1 o o M o 0 9 0 9 O 0 9 I 0 9 1 i $ ? 1 1 1 I i 1 8 t o t o 8 8 8 IO 1 0 8 8 8 10 10 * •0 8 8 8 8 8 O (A 0 9 + 0 8 A H rt A to •H A 8 A 8 a 3 a 8 A 5 ! A H IO a 0 k 1 0 a t o e - e a 8 0 9 IO 0 9 H rt H H V rt W rt V H V H V rt H A H • H V H 0 0 9 0 rt 0 rt s 8 A 8 A d A 8 A IO 1 0 A S a *0 rt A S 3 a 3 8 a rt 0 9 a * rt a flk « 8 6- IO M 0 9 0 9 H 9 0 9 0 9 V H 0 9 w rt • V rt w H V rt 0 9 0 0 9 0 0 9 s r t tO r t O IO I O * 09 • • • • I O k k O « B < D O Q r t O k O k l O O » O O O O i O i O O l l O l O O H i n * 1- Ai • • 01 IQ • O l O H l f t A l O i - I I O l O t t O O l O S S o H H Q O S rt to 9 U H M n n n • » • h * 0- ® « S K q 8 8 S S $ S S g i S IO t* Oi o i 01 01 * s s n S 3 X S & n u n s 3 I § i i S t 3 « S S 186 6 a & a g 3 8 0 8 § o « 3 2 I 2 § 3 8 rt rt rt 8 0 8 2 2 8 08 3 m 3 a V 8 'B 0 2 0 8 * 1 1 s | S i * | 3> 3 0 5 'B 8 8 5 8 3 0 1 0 8 8 8 8 •0 ^ B 1 0 •0 8 0 8 •0 ^ B I O n 8 rt « 0 8 3 3 3 2 3 3 1 i ft S S 1 1 3 3 1 § ■ I O 0 8 ■ J o 0 8 V i B 8 B I O o B 8 1 'B o I O B O 0 8 -S 8 'S 9 & 1 0 3 B 8 1 B S 1 B I O 08 8 I O 8 8 8 I O * I O 8 d 0 0 g ^ B 8 8 8 h 8 8 1 S 1 8 * % 1 0 1 * 1 % & 1 * rt d 3 8 d 3 a O rt d to t- d I D 1 0 O 0 8 a to rt a 8 A 3 8 3 s rt 0 8 H rt H rt rt rt w rt V rt V rt W rt # rt • rt # rt # 08 • H % rt a d rt O d d 1 0 0 8 A 8 A rt t- d rt C O a 8 * rt a > a rt 1 0 A 8 8 A 8 8 8 1 H rt H 0 4 rt W •0 * w * rt # I O • rt # 8 • + • t* rt *• 1 0 C O I O 08 0 2 3 S 3 ai 0 8 3 8 3 o 0 8 8 rt 08 8 8 • 1 • • • # • 1 • • • • • 1 • • • 8 • • • 8 3 8 3 3 S S 3 8 3 3 8 8 8 & 3 08 a s s i i i i s S s i s S i S l i 5 i l l l | 3 3 M g g g g g g g V I O l O l O l O l O l O l O l O l O l O l O N O l O l O l O 189 e I 1 * • * § 3 i § I S § 1 3 « & * IO oa t o rt t o ?> rt t o ■m to oa ■ 3 *B 3 * 'B IO • 0 h * 5 | oa ' 8 a % to % 8 H 10 8 IO oa 8 £ i i i 8 8 3 r t a d ^ B 8 3 1 1 % % 3 o 3 3 O a °3 O 3 O^ 3°33°3 o 3 O 3 8 o V) B IO rt t o s 8 t o o n t o u> *1 § g> 1 to to o o* • 0 <r ? # to r ?• ? ? o* n 1 0 S 3 o ( 0 3 8 3 8 8 8 8 8 ■ 0 1 0 8 8 8 to IO o oa 0» ¥> 0 3 0 CO oa 0 0» 0> 0 oa oa 0 O > 0 0 to rt t o a t o * rt t o 8 3 8 t o s to 0 1 8 t o a M r tr t H r t H W rt w rt V rt • rt • rt rt # rt • rt 9 rt • rt 2 0 1 o> 0 3 0 g 0 oa » 0 8 0 3 t o e» to t o IO o t o IO Ot 8 8 t o 9 9 t o rt to 3 to ao CO H 1 V rt oa ♦ rt # oa V 10 • # ■ # § 190 o a rl ID 0 » 3 e - > o 2 H CO i 4 6 0 6 7 0 ■ m 8 H a 9 ■ 9 & 5 * 3 8 i b H a 3 S 3 a 8 0 * 0 * % o t * o t - O t - o t * o b » %- 8- a d H H d d d a O* r - o b- o ▻ 3 o 0Q S o a S g a IO IO IO IO IO <0 s IO o H s IO r l 8 8 8 to r l 8 <? *0 w ,S o «0 1 oa w a> <5* A f t b- <r> oa o b* <P M b* o" M * AS IO o * M 0 Aft IO O* M o* AO * AO $ 8 0 w A ot IO 8 OT IO s OT 10 b - 0 1 A H 10 0 01 A to A to H 9 £ t * H £ t o 10 b- b- A 8 a 2 A • 01 A 3 A iH 8 H V H V rl rl H iH H H V H V H W H W H a a 3 a IO 0 1 A 2 A •H O A 2 I O H A oa 10 a to 01 A 0 01 A 9 a d A V 9 i - t V 1 • V I 1 o a w H V V H w • V IO o A 9 A a a I O 01 A o A 10 0 01 o I O o a A 8 a 8 A rl oa A 2 A l O O t A 1 i V • • 1 1 W • V V V 1 8 A IO ot A a a Ok 10 A s £ ? £ 8 A 0 1 t- A 8 A 8 A 8 A 9 A 8 A V V H V V w V W H W •076 & H • i • •H S • rl 8 • •066 2 O • a • 1 • 3 • to 8 • § • u n fi: ^ IO lO ® 2 H « p 0 t N > 1 0 I O I O S U M IO 10 IO to to 6 7 9 7 * 0 6 6 * 6 0 * 1 6 6 . 0 0 1 . 8 8 5 8 ° 4 9 '6 8 * H 7 ° 8 1 * 4 0 " 6 4 0 6 7 6 8 . 6 7 4 * 9 8 - . 1 6 - . 5 1 1 . 6 6 6 8 ° 4 6 * 6 0 ” 1 1 7 ° 8 0 * 2 5 * 1 1 1 6 7 7 0 . 0 6 4 1 * 4 6 - . 6 6 . 0 7 1 . 4 7 5 8 ° 6 5 ' 6 8 " 1 1 7 ° 1 7 ' 6 6 * 8 1 9 191 m m m w m S O tO Q (O h to n to » ■ B 'B * 8 <8 B -B " 5 n n 5 « 8 f i l l 1 <0 10 to y y a* 3 3 3 to * a S 8 to o 0 o to oa 8 8 8 t o H IO 10 8 8 s s 8 8 8 5 to ¥> t O H h 8 2 3 3 £ & to & IO 1 % 10 3 % 10 3 3 3 % to 3 3 3 s s A H 01 A t o oa s A 8 a 8 a H H A 2 A 2 * 2 A 3 A 2 w H V H 8 rl 0) V H W rl H V H • rl V H • H * W rl • H g A IO H 0- 01 A O f t H IO oa a 8 A oa CO £ IO 10 a 8 A S a 3 A OI IO 01 01 A w 01 w W H V 1 oa V H V H rl A S A to 10 a A H 01 . a 3 A 8 A 3 A g B f c 8 a 8 A 3 a oa 10 a o t o A V « w w 1 V V w 1 V V V • V • V 3 09 S 0 9 S 5 to § 8 87 8 48 •0 99 • H • * rl • • • IO ot 10 e* H 8 3 8 to o 8 3 • • • • • • 6774 IO E IO 6806 6810 3 8 6813 • • ■0 H • • • • • • • • • i 1 1 i i i 008 *86 .15 0*47 1.11 54°14 * 50" 119°88*31" 192 a H CO to * r t IO IO t- g 8 3 r t 210 8 t* CO 3 Ot 931 § 3 3 144 b 8 t o & « M 1 | B 8 1 8 £ 8 * 5 % * * i H ? rt s 1 2 | H 8 2 s O at 9 • i at 3 £ at at ! ? at t o o« 8 Ot 8 O at ? ? <b a a 3 3 3 3 3 a 3 3 a a 3 a a ■4 • a ■ 8 8 o M % 3 8 8 £ B 8 % B 8 a 1 B 8 B 8 8 3 3 <0 H 2, H A rt O 8 a i i £ 5 ? 1 t o ? £ ? t o A 8 A ? ot 8 X 8 8 8 8 8 8 8 8 8 8 8 8 3 8 o M ■o • M 0 Ok H 3 0- 01 A 3 A s A 3 A 8 s 8 3 at rt 3 8 VJ rt rt H H H w H W rt rt V H • rt 9 rt 9 rt 9 oa 9 oa 9 r t 9 ot s CO oa ■ IO OH 0 to 10 H «0 to C * to 0 9 8 a 8 a IO H a 8 8 a a to oa s 8 A r t A r t 0 ) H r t V rt oa V • # rt 9 1 9 9 9 9 • & S 0* o IO oa A o 10 e* to IO 8 8 10 oa 8 8 8 8 8 © 8 E • • • i • • • • • • • • • 9 1 9 • • • • 1 g 8 • 5 ! • 8 • *1 oa • 3 • 3 • IO O’ • 8 • e* CD • • 8 • 8 9 3 9 • 8 9 rt A • H r t r t H H r t H r t a 3 • 0) 8 • 0* s • o • ot 8 • e» 8 • 3 O • t • 8 • to O • § 9 § • I • 3 • i • »11 i I i I i 1 i 111 i i ! 1 • • • • • • • • H CO H H H H tO H « 0 • l i t • • • • • * • • • • • • * • • • i S a 8 3 S : S U 8 S ! 5 s • t o o 1 • 8 • • 8 H • 8 1.51 • Ol • 3 t o • - a 08*8 ( 0 • 3 H • o a « H 8 M m O I a M A M „ a H A H A H A H a H A H H W t 8 V to OI V H « V O I H W ■ 3 O l W 2 V t o t o t o O l 8 • 0 1 d O I Oi 8 <* O i O I 8 0 1 8 8 8 8 8 2 O 8 i £ O P o H * O 8 o K £ O P £ £ Ol ■ £ 1 8 ■ £ O l a 8 a 8 a i p £ e £ p B P p p P p t * * O o • o « o « > O • o to o • o « > o s e 8 to • 0 O l 8 0 1 0 1 0 1 0 1 p B 8 oS i OI <5 8 a - i 6 ■ 8 S ' i % s a- O l s t o s t o - a OI 3 2 8 9 t o s 5 i § s t H • O • to CD 8 H O l t o t o • • C O o W o E W S K o l « > S 8 ' a P P % ■ 8 s 8 H t o 8 8 £ a - a • 0 6 2 8 s« 94 T »03 * S9 o 9 T T »83 «O O o9 ? 93*1 99*3 14 * 44 * 090 * 9469 * 3 3 3 3 8 5 8 8 8 8 8 g> ® « <p • • « 01 01 - h o -a § s • • • • • • • • • • • • • • i § § i § i i i § i § i § i § B • • • • • • • • t t • • • • • M S 3 « 8 6 f i S S g i S S S 8 8 : i 8 I 8 g I 0* -9 10 t o • • I H b» * A H* H 1 a 0 01 b 8 g b H V Ok <D CO s H 10 t o 8 H M M CO ! 0 H M H » M H ' - 4 i £ M O *oiH»i»a»Gi oioa» l l i S S I S S S S S S S S S 8 g 8 g 8 8 8 g S 8 8 P 8 S S g i i i i i i i i i ? i % t i t 8 S 5 8 8 S S 5 8 8 3 S * 8 8 8 8 8 8 8 8 S 8 8 <0 8 P 8 l 2 f e 8 f e f e 8 s S s 2 f e 8 96 T 195 i 3 ! ! E i t 8 3 3 ! i i 3 ! E I S )5 5 n Vii 5 ' a H J i S ’ l l a l s E i i i s s s s s i s b a i S 8 8 S S 3 2 8 S S S 3 8 8 S 8 I I I I ^ ^ ^ * ? ? ? ? ? $ ? ? n n n n n 2 n n 2 00 03 g 8 0 2 £ 0 01 0 8 0 2 0 H 01 A 8 A 8 A 8 a 3 ? 8 5 a 8 8 to H H H rt H 01 H V rt V H V H # rt • H V H # H # rt # rt 3 # S 0 8 0 3 0 3 £ p4 O £ <0 10 A + at A * 01 A 01 e» a to 0 a 3 a 2 8 e- « 01 A H V H V H 01 • H v H 01 • rH • H • H •47 + 01 . •18 to 01 • 8 • 8 • <o 01 * * • 8 • •26 8 • 2 • 8 • H e • to t o • 8 + g 8 74 3 85 84 I: 8 8 8 o • • • • • • l - t • H • H • • rt an § i 058 960 129 051 TOO § 058 061 • • • • • • • • 0 • M oa S 6977 5978 IO 8 IO 5996 5997 5998 g to 6000 6001 • • 1 11 i i 1 i 196 e § 3 8 3 S i g a 8 3 S P S 8 S S P r t r t r t O i O I V > O t O « r t m) « 0 o u m> a o 10 ^ n n % h h h h h h 9 # a h o o » o 9 i l i f g i l i l i i i l l i n 9 9 9 a ^ S 3 i ^ CO s OQ 8 8 I O I O 3 8 8 I O rt 8 8 C O O l 3 o o 8 8 I O Ol 3 O m s? 5> «■ * ? f 5> 8* I m 1 0 o 0 1 y 1 I § 01 ff 01 «* 3 3 3 3 s *• I O + n I O 1 0 • 0 8 1 0 8 8 8 8 3 A 5 A % A S a & A 8 £ 3 0 I O o A 0 0 1 0 8 A 8 A 5 a I O 1 0 A « rt 3 a W rt V H V H w r l 0 1 rt rt O l H CM V rt Oi V rt • rt V rt 3 0 8 a 8 A I O < 0 A rt 0 > A 8 A a A a 0 < 0 O i A 01 O i A 0- 0 1 A o » 0 H V V H V i H rt w rt H V 1 w H w 1 0 S > • 3 • 0 1 « « •5 0 8 • rt 01 • 8 • 3 • .2 7 •16 s • .17 * rt • •06 • • • • • 0- + • • . u a n • • • H 9 3 § I § 1 I • • • • • b- 8 • • • • 8 m io t- rt 8 8 8 8 • • 8 3 3 8 3 3 3 3 8 8 8 8 8 8 3 1 8 8 8 8 8 8 8 8 8 8 8 8 8 8 ■9919000X1 * 3 9 199o99 33*1 XfX 00* 9t* Z . 9 0 * 90X9 197 oa oa S I 9 1 o 2 3 i a 2 01 s a a § 8 8 M 9 H r H 3 t- rt V g t o 1 ' u a IO a a t o a a 1 s % a $ ’ ? * 2 2 i a rt 5 a a A Ok 8 * a ? i 4 % i j t o ? j t o t o rt j t o 1 ? i 1 I I t o ? a a a 0 9 2 W rl r H 09 a 09 a a rt 09 rt rt 3 r H w 3 0 1 3 09 3 o 3 5 1 8 | U > rt 8 t o -« 3 t o 'B 8 t o m a t o B s t o 3 a rt ■B 8 t o 3 t o * t o a a t 9 I i a 1 0 rt S' * 1 0 rt s ' a a a S1 a a 2 a 5 * a a ? 2 rl S ' 2 £ 2 a ? 2 a y 2 S * 2 a *• 2 a * 2 0 1 a • 0 1 Ol * S a 2 8 a a a a rt 0 1 a a 0- a rt a a 8 A 3 a 9 2 3 Ok rt 8 rt a 0 1 N 0 1 0 1 H a rt a rt a r l a rt # rt • rt 9 rt # rt 9 rt 9 rt 9 • 9 a 8 a a 8 a 8 a 0- a a a 9 A t- Ol a a a 8 3 8 A 8 8 1 rt rl a rl a a a • rl 9 rt 9 a ■ • • 9 • 8 # 8 a 8 a % a 3 a s a 8 a 2 a 9 a s 8 Ok a rt a 3 a 8 a o • • a a a • • 9 • • a i • 1 • i O rt • 2 a Ok 1 0 a I O o a 2 a 8 a O l a a rt o A 8 a 9 a o » g £ 2 8 rl a 01 rt 0 1 a 0 1 a rt a rt a rl 9 9 • rl 9 9 • 9 * 8 • Ok 8 • 3 • a 8 • a 8 • 2 O • 1 • a 8 » rt 8 • rt a o • § • § • I • § • 8 • 2 o 9 6107 6131 0 1 a < 0 2 a 3 a a 3 a 2 rt a 6166 28 rt a 6167 6168 3 9 § 8 9 6898 8 3 198 g 5 3 8 3 S 3 § 3 § 2 g 3 3 3 8 8 9 1 2 I 9 a K • 9 8 9 m 3 io V A « t- * Ok V g^ 3 tli 3 2 2 «o rt « 8 8 O 5 i • S' * ■0 3 3 a; 0 01 £ 8 s A si A rt rt rt rt <0 t- • 8 • Ok 10 • S • o « 3 3 3 S 3 8 8 8 3 s > 3 3 8 3 8 « ! • • • • • • • • • • • • • • • • r t r t r t r t r t r t O l r t r t r t r t r t r t r t r t r t « S 8 aI a[ S 3 3 g 8 8 8 8 3 8 8 3 « • ■ • h * * * * r i* i# i* r » S 8 3 8 8 8 9 8 8 3 3 8 8 8 8 8 . m • i i • i l I I g n s n , n ; i j u n n H H H H a | ? ? |iss r 1 3i i s 1 11 • • • • • • • • • • • • • • • 9 m oa 199 91 ■0 8«T6olTT ■8 9.08o99 1T*T 99 ■OO18S0ITI ■9 9.08o99 88*1 98 ■9 9i98o&TT *0 0 .8 So 99 83*T 98 *99.990111 « 9 0 i 3 8 o 9 9 8T*T 81 *9 6.66olTT h 0 I . 8 8 o 9 9 13*1 8 *0 9*99olTT m 8 I i8 8 o 9 9 91*1 86 »9 6«89olTT *9 9.16o66 19*1 09 «0 9i89olII *0 0.89o99 9 8* T 88 *0 3»89olTT *0Ii88o99 03*1 09 1 1 OO 1IO08II n 9 8 i 6 9 o 8 9 9T*T 09 h 0 9 i0 0 o 9 H »8 8»68088 08*1 09 *9 6»00o8TT a0 9i69o99 1T*T 88 *8 8i00o8II *86.66066 88*1 09 «0 0i90o8II a3 8i09o99 89*1 98 ■9 9 .80o8H « 9 9 . 0 9 o 9 9 09*1 08 a0 9 i80o8II » 0 0 iT 9 o S 9 81*1 01 8801 Sfl 08 90* 9 0* 99* 160* 8899 90*- TO* 99* 890* 1899 33*- 80*- 99* 810* 9899 90* 00* 98* 980* 9899 88*- 90*- 99* 801* 9899 9 1* 80*- 99* 91T* 9899 88*- OT*- T9* 990* 1199 10* 10* 99* 910* 9199 1 3*- 9 9* TOT* 9199 to o • • 0 01 69* 910* 9199 90* 90* 89* 910* 8199 90* 90* 99* 980* T199 31*- 19* TOT* 0199 98*- 90*- 99* 960* 6999 88*- 89*- 88* 060* 8999 39*- 3T*- 99* TOT* 1999 688 g i d 088 OR 18 200 g S 3 8 3 8 3 3 8 3 8 8 3 5 8 S S % * « JO | * 3 ■ 2 & O % > o | B 8 O B 10 H M ) «0 % 3 8 'B IO H to I H * > e- H * > H e- 1 t- Ok 0- * 1 0- c to e 6- <» S * IO * 0* I e- I I I ? a a a a a a rl rl a a H H a 3 a 3 a a • s '■ 10 M o M M > H '■ a B s 1 s 8 B 3 s 3 s a B 8 '8 3 3 o ? ? * ? 1 1 9 9 9 9 9 9 9 9 9 9 8 10 10 8 8 8 8 8 8 8 8 8 8 8 n to 8 8 o «a 8 • H 8 # H 8 • H 3 • H H • rl 3 • H 1 . 1 6 H • H 3 • rl 03 10 • H rl 10 • H k O 03 • H O * • H i • rl 03 • rl 8 • rt M 8 8 & 8 8 H O 8 iH O 3 3 t - to c 8 8 8 S S o a • • • • • • • • • • • • • 1 • 1 • 1 • • 8 3 8 3 3 8 8 3 8 8 8 8 n o • • I 8 m oa < 0 8 072 088 090 i 088 106 097 074 • • • • • • • • • 8 8 6991 8 8 6595 s 8 6596 «o 0 k 8 0k 8 6598 • • • • • Mill 201 8 * 01 8 at n at A 3 S 8 8 O 00 3 8 €0 00 O n u> 00 $ ■ 8 u> n 3 & 10 10 % A IP 1 % O s 1 9 a a 8 to H 8 8 8 8 8 8 1 8 8 8 s. 8 *. % % ?- ?. O b- ?. b* f. O f c » ?. a 3 S A A 3 3 A A H H 3 A 3 e- t» H d 853 383 33 388 888 888 ^ s 1 I ? ? .s H H H H n nn iQ io ni Qnn ioi oioi o io ioi o o 00 8 8 3 S 3 8 2 H ^ H N lj| t> IO 00 00 Ot) 01 IO • I t * 10 00 00 • • • • s 01 8 8 o at b- 88888888 • • * • • • • • • I g 8 8 8 8 8. 8 8 3 8 8 8 8 8 3 8 I tO b- IO r-l lO to io a o Vt • • • • • 8 8 8 8 3 8 * * * * * • • • • b - to to • • • • s 3 3 3 H » S 2 3 3 3 s 3 5 I s S • • • •9 * to to t» I i I § i I i 2 2 I n SM MD PSD PPS 8PS 6674 •064 •76 •23 2.42 6676 •068 •43 -•10 1.69 6680 •066 •69 .78 2*73 6691 •366 1.50 •64 1.04 6692 •489 1.11 -•66 6693 •146 .70 -.34 -.65 6696 •084 •52 •16 2.11 6696 •066 1.19 •11 1.07 6698 •072 •63 .24 2.13 6699 •092 •34 •03 -•06 6600 •068 •46 •01 1.01 6601 •090 1.79 -.63 -.13 6602 •060 1.60 -.63 •22 6603 •063 •62 •06 1.68 6604 •086 •34 -•02 •88 6606 •107 •48 •09 •49 SO LAS LOHO ID 1.26 32°64*28" 117016*60" 240 1.21 32<>64»28" 117016*20” 120 1.22 32061*30" 117019*36" 276 1.69 32°61t251 1 117018*30" 166 1.36 32051*26" 117017*00" 64 1.37 32061*26" 117016*10" 66 1.30 32061*68" 117017*20" 180 1.63 32062*00" 117018*16" 210 1.32 32062*46" 117016*20” 168 1.16 32063*20" 117016*46" 60 1.25 38063*22" 117016*16" 138 1.60 32063*22" 117016*60" 868 1.36 38066*40" 117018*30" 864 1*30 88066*66" 117017*80" 166 1«16 52066*00" 117016*16" 60 1.23 32066*46" 117016*46" 66 205 *38 e s s I a § s & I 8 I a 5 1 a a I s ? s 8 s 8 s s n s i n U ; $ ; 3 a a a S d a a a 3 § 3 a 3 3 3 B B B B B B B B B ‘B <B 'B 'B B B B ! 8 3 3 S 8 ! S 8 8 5 2 h 8 8 a s s s s g g s s s s i s s j s s & & & & n t i ^ 5 S S S S S S S o 8 2 3 U 8 S S 5 S ! * ’ ^ OS • • • • H H H • • H H •O Wi tO Oi i - l OH • • • • • • s oa s n n a s a s s a g s s s • • • • • * • • « • • • • • * *“■ • • I HI I I I a s a a a s a s s s a s s a a s s E i i • i f t* • f • • f f ;• " 2 s s u , n n i s : ; : : n • m m ; m h ; m i i i i i M S i i i i < o i o « S « < o » S S S S S * 8 s i * * ^ • * 8 8 (04 g 5 8 8 S 3 8 8 § § 8 3 3 £ § 8 8 ■ ■■ ■ f c <m • * -m • -a ■ <a <a <a -a •* S 3 3 8 5 3 S 3 3 S 8 3 3 8 8 3 8 8 S 8 8 8 3 s ii l 8 8 9 9 :i ) £ ) S d a s s d s s s a s s s a a d s 3 3 8 8 3 % M 8 IO 04 ■ ■ k v 1 ■ -m ' m 'm ■■ 3 3 3 3 3 3 8 3 3 I I I ? ! 1! ? ? ? ? ? ? ! ? ! 1 3 3 3 3 8 3 3 3 3 3 3 3 3 3 3 O o n < o 10 to iH 01 IO a 04 IO 04 • • H rH £• tO O to e» io • • • 10 H H 8 8 H 0) 8 10 rH 5? 04 4 oa • to » oi to to e» h oi t» o o h co c- • 9 to 8 9 3 3 3 3 8 8 • • 01 H IO • • • I I 8 3 3 8 8 8 8 8 8 3 3 3 8 3 8 3 • • • • I § 8 8 3 8 8 8 8 3 8 8 3 3 8 8 8 3 M * 4 * * 4 4 4 4 ( 4 - H 01 H • • rl 01 a I i 2 8 I. I I 3 I I I I IS 3 i to $ o» 8 o *) s $ & ^ ^ ^ « « to to to to j r Q ^ t 6» ^ ^ - totototototototototo fc06 e S 3 i o a M H S ^ o ^ t - o a o e - a m n H H M M n H M a n n s a a | | » h H ? H ?? H ? 1 1 5 5 3 3 3 2 3 3 3 3 2 3 3 v '■ « w m m ' W w ‘W -m 'W •m m 1 m w 8 8 8 3 S S 8 8 3 8 8 8 8 3 3 s s n s n s j i s s i i s j i s o o o o o o o o o o o o ooo ^ < O C D O » 1> Q Q « I O l O I O > O Q H O I b © O J W N N r ^ H r H r - I W O l O l i o OS • t » • H r4 • • • H H M CO • • • 2 OS iH I O *0 rt * a S 8 s a H (0 lO O OS CO O O O 6- O O- a * a a a a ▼ “ • 1 V • • w w W w w l I g • • • i i i Ol IO 8 a lO rt a 3 a 1 w 1 V • w i h a co to « i o 7 n 10 to o m O S to 10 I Q 3 oa s 3 S • • e- to s g g g 8 g g g s g g He n g O O « « to tD(OtOtOtO«tOIDtOtO nfifi9To6II M9tiOTott TVT W- 90* I / . * til* 681,9 206 e n s n s s si s s n n s 8 M 01 B ■ • B B B 'B B 'B 'B 'B -8 <8 <8 H $ 8 $ S 8 5 2 3 3 8 o i S 8 00 0* 03 E § 3 3 2 Ot 10 lO rt O Ot 10 rt O rt 8 8 8 IO 2 M) 10 '8 s 5> rt °3 8 % 10 § 3 % •0 i> % •0 rt O % ? 3 gj ? 2 1 2 § 2 i rt ? 2 rt ? 3 rt ? 2 rt ? 2 * 10 0 9 0 a 0 ot ¥i 0 8 0 Ot A ca Ok H & rt Ot A 00 Ot * rt A S A t- lO < 0 » 00 A s A H H rt rt rt V rt H w V rt w rt V rt W rt rt V rt rt e* 10 0 rt ■0 a IO Ok 0 to Ok 0 00 00 e» ot a 2 8 A 8 a IO A S A 00 Ot A <0 6* 8 A rt o A w rt Ot w • 1 V V V • w •* V « •? 8 0 8 3 0 8 a o ot A a a 8 a 8 A 0 01 A 8 a IO ot A 3 A b* (0 a 8 A 8 a 1 1 W • w • i V W 1 V V • w • w 1 w • V t rt IO . IO Ot • <0 *0 • 8 • 2 . 5 . b- kQ • IO 10 * 3 • Ok * • 2 • 3 • 3 . 2 . 2 • a 3 I § I 1 2 i I I a I 2 2 3 I • . • • • • • • • « S 5 5 S S 5 3 3 S S 3 3 3 S S £ l O O O O O O O O O O O O O l O O 6769 *046 1*82 .6 2 1.28 1.80 54°01'00" U8°81'16" 807 s 3 m S « g o rt 8 3 8 270 ■ 8 m u> rt • » 0 01 m « 8 1 I #n A 01 O I 1 0k § V a a w rt rt S VU H H 8 U5 U) m « 8 ■ 5 K IO m i at IO A 2 A o 10 A 5 A w *1 •0 IO w W s W 8 W 10 •0 00 rt a 3 a 0* 01 A rl 01 A rl V rt V H w rt W rt 8 A 8 A lO IO A a A 0 01 £ V • ■ 1 V H 1 8 3 A a a 8 A rl A A • V • V V 8 • 8 • t- * • 3 • s • s a S 3 § I . O r l 0 9 3! » « « « « « ea t- e* e- t" t> « o « « «

Asset Metadata

Creator Wimberley, Stanley (author)

Core Title Sediments Of The Southern California Mainland Shelf

Contributor Digitized by ProQuest (provenance)

Degree Doctor of Philosophy

Degree Program Geology

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag Geology,OAI-PMH Harvest

Language English

Advisor Emery, Kenneth O. (committee chair), Bandy, Orville L. (committee member), Merriam, Richard (committee member), Reith, John W. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c18-347475

Unique identifier UC11358988

Identifier 6413514.pdf (filename),usctheses-c18-347475 (legacy record id)

Legacy Identifier 6413514.pdf

Dmrecord 347475

Document Type Dissertation

Rights Wimberley, Stanley

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA

Linked assets

University of Southern California Dissertations and Theses