Crater Lake
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| Crater Lake, Oregon | |
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| Coordinates | |
| Lake type | crater lake |
| Primary sources | precipitation only |
| Primary outflows | evaporation only |
| Basin countries | USA (Oregon) |
| Max-length | 6 mi (9.6 km) |
| Max-width | 5 mi (8 km) |
| Surface area | 20.5 sq mi (53.2 km²) |
| Average depth | 1,148 ft (350 m) |
| Max-depth | 1,949 ft (594 m) |
| Water volume | 4.19 cu mi (17.46 km³) |
| Residence time (of lake water) | 250 years |
| Shore length1 | 21.8 mi (35.1 km) |
| Surface elevation | 6,178 ft (1,883 m) |
| Islands | Wizard Island |
| 1 Shore length is an imprecise measure which may not be standardized for this article. | |
- For the general term of a geological feature that goes by the same name, see crater lake.
Crater Lake is a caldera lake in the U.S. state of Oregon. It is the main feature of Crater Lake National Park and famous for its deep blue color and water clarity. The lake partly fills a nearly 4,000 feet (1,220 m) deep caldera that was formed around 7,700 years ago by the collapse of the volcano Mount Mazama.
The lake is 5 by 6 miles (8 by 9.6 km) with an average depth of 1,148 feet (350 m). Its deepest point has been measured at 1,949 feet (594 m) deep,[1] though as with any lake its depth fluctuates with the climate, particularly rainfall,[2] This makes Crater Lake the deepest lake in the United States, the second deepest lake in North America (Great Slave Lake is the deepest) and the seventh deepest lake in the world (Lake Baikal is the deepest). It also holds the honor of being the deepest lake in the world that is completely above sea level. The caldera rim ranges in elevation from 7,000 to 8,000 feet (2,130 to 2,440 m).
On June 12, 1853, John Wesley Hillman was reportedly the first European American to see what he named "Deep Blue Lake" in Oregon. The lake was subsequently renamed Crater Lake.
Crater Lake is known for its famous piece of driftwood named the "Old Man of the Lake." It is a full-sized tree that has been bobbing vertically in the lake for more than a century. Due to the cold water of the lake, the tree has been rather well preserved.
The commemorative Oregon State Quarter, which was released by the United States Mint in 2005, features an image of Crater Lake on its reverse side.
[edit] Geology
Mount Mazama, part of the Cascade Range volcanic arc, was built up mostly of andesite, dacite, and rhyodacite over a period of at least 400,000 years. The caldera was created in a massive volcanic eruption that lead to the subsidence of Mount Mazama around 5700 BC: about 50 cubic kilometers (12 cubic miles) of rhyodacite was erupted in this event. Since that time, all eruptions on Mazama have been confined to the caldera.
Lava eruptions later created a central platform, Wizard Island, Merriam Cone, and other, smaller volcanic features, including a rhyodacite dome that was eventually created atop the central platform. Sediments and landslide debris also covered the caldera floor.
In time, the caldera cooled, allowing rain and snow to accumulate and eventually form a lake. Landslides from the caldera rim thereafter formed debris fans and turbidite sediments on the lakebed. Fumaroles and hot springs remained common and active during this period.
Also after some time, the slopes of the lake's caldera rim more or less stabilized, streams restored a radial drainage pattern on the mountain, and dense forests began to revegetate the barren landscape.
Some hydrothermal activity remains along the lake floor, suggesting that at sometime in the future Mazama may erupt once again.[3]
[edit] Water quality
Due to several factors, most prominently that it has no inlets or tributaries, the waters of Crater Lake are some of the purest in terms of the absence of pollutants in North America.
Secchi disk clarity readings have consistently been in the high-20 metre to mid-30 meter (80-115 ft) range, which is very clear for any natural body of water. In 1997, scientists recorded a record clarity of 43.3 meters (142 ft). The lake traditionally has relatively high levels of dissolved salts, total alkalinity, and conductivity. The average pH has generally ranged between 7 and 8.
[edit] References
- ^ Facts about Crater Lake. U.S. Geological Survey. Retrieved on 2006-11-23.
- ^ Gibbons, Helen (September, 2000). CMG Maps Bottom of Crater Lake, Oregon. U.S. Geological Survey. Retrieved on 2006-11-23.
- ^ Geologic History of Crater Lake. U.S. Geological Survey. Retrieved on 2006-11-23.
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Wikimedia Commons has media related to: |
- Fire Mountains of the West: The Cascade and Mono Lake Volcanoes, Stephen L. Harris, (Mountain Press Publishing Company, Missoula; 1988) ISBN 0-87842-220-X
- Geology of National Parks: Fifth Edition, Ann G. Harris, Esther Tuttle, Sherwood D., Tuttle (Iowa, Kendall/Hunt Publishing; 1997) ISBN 0-7872-5353-7
- Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon, Charles R. Bacon and Marvin A. Lanphere, Geological Society of American Bulletin v. 118, p. 1331-1359 (2006) DOI: 10.1130/B25906.1
[edit] External links
- Crater Lake Data Clearinghouse of the United States Geological Survey
- Diving into mysterious Crater Lake - CNET News.com (August 25, 2006)
- Maps and aerial photos
- WikiSatellite view at WikiMapia
- Topographic map from TopoZone
- Aerial image from TerraServer-USA
- Surrounding area map from Google Maps
- Location in the United States from the Census Bureau
