page_title: Crater Lake National Park
section_title: Geology
hierarchical_section_title: Crater Lake National Park / Geology
caption_attribution_description: English: The raw satellite imagery shown in these images was obtained from NASA and/or the US Geological Survey. Post-processing and production by www.terraprints.com
context_page_description: Crater Lake National Park is an American national park located in southern Oregon. Established in 1902, Crater Lake is the fifth-oldest national park in the United States and the only national park in Oregon. The park encompasses the caldera of Crater Lake, a remnant of a destroyed volcano, Mount Mazama, and the surrounding hills and forests.
  The lake is 1,949 feet deep at its deepest point, which makes it the deepest lake in the United States, the second-deepest in North America and the ninth-deepest in the world. Crater Lake is often referred to as the seventh-deepest lake in the world, but this former listing excludes the approximately 3,000-foot depth of subglacial Lake Vostok in Antarctica, which resides under nearly 13,000 feet of ice, and the recent report of a 2,740-foot maximum depth for Lake O'Higgins/San Martin, located on the border of Chile and Argentina. However, when comparing its average depth of 1,148 feet to the average depth of other deep lakes, Crater Lake becomes the deepest in the Western Hemisphere and the third-deepest in the world.
context_section_description: Volcanic activity in this area is fed by subduction off the coast of Oregon as the Juan de Fuca Plate slips below the North American Plate (see plate tectonics). Heat and compression generated by this movement has created a mountain chain topped by a series of volcanoes, which together are called the Cascade Range.  The large volcanoes in the range are called the High Cascades. However, there are many other volcanoes in the range as well, most of which are much smaller.
  About 400,000 years ago, Mount Mazama began its existence in much the same way as the other mountains of the High Cascades, as overlapping shield volcanoes. Over time, alternating layers of lava flows and pyroclastic flows built Mazama's overlapping cones until it reached about 11,000 feet (3,400 m) in height.
  As the young stratovolcano grew, many smaller volcanoes and volcanic vents were built in the area of the park and just outside what are now the park's borders. Chief among these were cinder cones. Although the early examples are gone—cinder cones erode easily—there are at least 13 much younger cinder cones in the park, and at least another 11 or so outside its borders, that still retain their distinctive cinder cone appearance. There continues to be debate as to whether these minor volcanoes and vents were parasitic to Mazama's magma chamber and system or if they were related to background Oregon Cascade volcanism.
  After a period of dormancy, Mazama became active again. Then, around 5700 BC, Mazama collapsed into itself during a tremendous volcanic eruption, losing 2,500 to 3,500 feet (760 to 1,070 m) in height. The eruption formed a large caldera that, depending on the prevailing climate, was filled in about 740 years, forming a beautiful lake with a deep blue hue, known today as Crater Lake.
  The eruptive period that decapitated Mazama also laid waste to much of the greater Crater Lake area and deposited ash as far east as the northwest corner of what is now Yellowstone National Park, as far south as central Nevada, and as far north as southern British Columbia. It produced more than 150 times as much ash as the May 18, 1980 eruption of Mount St. Helens.
  This ash has since developed a soil type called andisol. Soils in Crater Lake National Park are brown, dark brown or dark grayish-brown sandy loams or loamy sands which have plentiful cobbles, gravel and stones. They are slightly to moderately acidic and their drainage is somewhat excessive.
caption: Satellite view of Crater Lake
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