Photograph of a panoramic view of Crater Lake, Oregon, ca.1900-1940. The edges of the lake rise above the water level and appear to be at a steeply inclined, which gives the lake the crater look. A small island (or rock formation?) juts above the water near the shores on the opposite side (at left). Trees cover the cliffs (or mountainous area) in the foreground.; "The lake was formed after the collapse of an ancient volcano, posthumously named Mount Mazama. This volcano violently erupted approximately 7700 years ago. That eruption was 42 times as powerful as the 1980 eruption of Mt. St. Helens. The basin or caldera was formed after the top 5000 feet of the volcano collapsed. Subsequent lava flows sealed the bottom, allowing the caldera to fill with approximately 4.6 trillion gallons of water from rainfall and snow melt, to create the seventh deepest lake in the world at 1,932 feet. Crater Lake is the deepest lake in the United States." -- unknown author.