Mount Mazama (Klamath: Tum-sum-ne) is a complex volcano in the western U.S. state of Oregon, in a segment of the Cascade Volcanic Arc and Cascade Range. The volcano is in Klamath County, in the southern Cascades, 60 miles (97 km) north of the Oregon–California border. Its collapse, due to the eruption of magma emptying the underlying magma chamber, formed a caldera that holds Crater Lake (Giiwas in the Klamath language). Mount Mazama originally had an elevation of approximately 12,000 feet (3,700 m), but following its climactic eruption this was reduced to 8,157 feet (2,486 m). Crater Lake is 1,943 feet (592 m) deep, the deepest freshwater body in the United States and the second deepest in North America after Great Slave Lake in Canada. Mount Mazama formed as a group of overlapping volcanic edifices such as shield volcanoes and small composite cones, becoming active intermittently until its climactic eruption 7,700 years ago. This eruption, the largest known within the Cascade Volcanic Arc in a million years, destroyed Mazama's summit, reducing its approximate 12,000-foot (3,700 m) height by about 1 mile (1,600 m). Much of the edifice fell into the volcano's partially emptied neck and magma chamber, creating a caldera. The region's volcanic activity results from the subduction at the Cascadia subduction zone, and is influenced by local extensional faulting. Mazama is dormant, but the U.S. Geological Survey says eruptions on a smaller scale are likely, which would pose a threat to its surroundings. Native Americans have inhabited the area around Mazama and Crater Lake for at least 10,000 years and the volcano plays an important role in local folklore. European-American settlers first reached the region in the mid-19th century. Since the late 19th century, the area has been extensively studied by scientists for its geological phenomena and more recently for its potential sources of geothermal energy. Crater Lake and Mazama's remnants sustain diverse ecosystems, which are closely monitored by the National Park Service because of their remoteness and ecological importance. Recreational activities including hiking, biking, snowshoeing, fishing, as well as cross-country skiing are available; during the summer, campgrounds and lodges at Crater Lake are open to visitors.
Geography Mount Mazama is in Klamath County, within the U.S. state of Oregon, 60 miles (97 km) north of the border with California. It lies in the southern portion of the Cascade Range. Crater Lake sits partly inside the volcano's caldera, with a depth of 1,943 feet (592 m); it is the deepest body of freshwater in the United States and the second deepest in North America after Great Slave Lake in Canada. Before its caldera-forming eruption, Mazama stood at an elevation between 10,800 and 12,100 feet (3,300 and 3,700 m), placing it about 1 mile (1.6 km) above the lake; this would have made it Oregon's highest peak. The Global Volcanism Program currently lists its elevation at 8,157 feet (2,486 m).
Crater Lake National Park
Crater Lake National Park covers an area of 250 square miles (650 km2), including forest areas, alpine terrain, the Crater Lake, and the vast majority of Mount Mazama. A wilderness area, it was dedicated in 1902 and is overseen by the National Park Service. It receives about 500,000 visitors each year, and these tourists can go hiking, take bike, ranger-guided, and trolley tours, swim, fish, camp, and participate in other recreational activities. While the park area remains open throughout the year, certain roads and facilities close in the winter season.
Physical geography
There was frequent glacier formation on the mountain as Mazama developed. They carved trenches in the flanks of the volcano in addition to U-shaped valleys under the base of the volcanic cone. These can be seen at three large glacial canyons on its southern slopes: Kerr Notch, Munson Valley, and Sun Notch. Whenever eruptions took place in the presence of ice, lava was chilled by glaciers, creating glassy talus deposits. Sometimes, the lava coursed into areas previously carved by glaciers like at Sentinel Rock, filling canyons with volcanic rock. Moraines occur up to 17 miles (27 km) from the rim of Mazama's caldera, and there are glacial striations visible at several sites in the area. When the climactic eruption occurred, the climate was warm and dry, and the most recent period of glacial advance ceased about 27,000 years ago, so by the time Mazama collapsed, ice was likely only present at higher elevations. Using argon geochronology and paleoclimatic records, scientists have identified that the Sand Creek, Sun Creek, and Annie Creek canyons were carved by the advance of ice over lava flows, pushing debris towards Klamath Marsh and Klamath Graben or nearby rivers. A glacial cirque can be seen on Mount Scott's northwestern flank, and glacial till occurs on Mazama's slopes, especially on the western slopes and at lower elevations. Till and fluvial sediments occur in the caldera walls, forming particularly thick deposits under Roundtop and Wineglass. Many lava flows that were glaciated have since been covered by more recent lava flows. Crater Lake formed from a network of lakes and ponds, eventually reaching a depth of 1,949 feet (594 m). Lake levels rose while the Wizard Island landform inside the crater was forming. Water interacted with lava flows to form pillow lava. Because of climate change patterns over time, Crater Lake's surface level has changed, dropping as much as 40 feet (12 m) for example at the beginning of the 20th century. The water from precipitation nearly equals water lost to evaporation and drainage, most leakage taking place at the Wineglass deposit at the northern side of the crater, without which the lake would likely have overflowed at the northern side. Average snowfall in the Crater Lake area has been decreasing since the 1930s. Crater Lake's mean surface water temperatures have increased about 5 °F (3 °C) since the 1960s. Though this may eventually cause algae to grow and obscure the water, Crater Lake remains one of the cleanest bodies of water in the world.
Geology
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