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Lassen Peak
Lassen Peak ( ), commonly referred to as Mount Lassen, is a lava dome volcano and the southernmost active volcano in the Cascade Range of the Western United States. Located in the Shasta Cascade region of Northern California, it is part of the Cascade Volcanic Arc, which stretches from southwestern British Columbia to northern California. Lassen Peak reaches an elevation of , standing above the northern Sacramento Valley. It supports many flora and fauna among its diverse habitats, which are subject to frequent snowfall and reach high elevations. Lassen Peak has a volume of , making it one of the largest lava domes on Earth. The volcano arose from the former northern flank of now-eroded Mount Tehama about 27,000 years ago, from a series of eruptions over the course of a few years. The mountain has been significantly eroded by glaciers over the last 25,000 years, and is now covered in talus deposits. On May 22, 1915, a powerful explosive eruption at Lassen Peak devastated nea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of The Most Prominent Summits Of The United States
The following sortable table comprises the 200 most topographically prominent mountain peaks of the United States of America. The summit of a mountain or hill may be measured in three principal ways: #The topographic elevation of a summit measures the height of the summit above a geodetic sea level.All elevations in the 48 states of the contiguous United States include an elevation adjustment from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the North American Vertical Datum of 1988 (NAVD 88). For further information, please see this United States National Geodetic Surveybr>noteIf the elevation or prominence of a summit is calculated as a range of values, the arithmetic mean is shown. #The topographic prominence of a summit is a measure of how high the summit rises above its surroundings.The topographic prominence of a summit is the topographic elevation difference between the summit and its highest or key col to a higher summit. The summit may be near its ke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive Eruption
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. Explosive eruptions can expel as much as per second of rocks, dust, gas and pyroclastic material, averaged over the duration of eruption, that travels at several hundred meters per second as high as into the atmosphere. This cloud may subsequently collapse, creating a fast-moving pyroclastic flow of hot volcanic matter. Stages of an explosive eruption An explosive eruption begins with some form of blockage in the crater of a volcano that prevents the release of gases trapped in highly viscous andesitic or rhyolitic magma. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lahar
A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extremely destructive: they can flow tens of metres per second, they have been known to be up to deep, and large flows tend to destroy any structures in their path. Notable lahars include those at Mount Pinatubo and Nevado del Ruiz, the latter of which killed thousands of people in the town of Armero. Etymology The word ''lahar'' is of Javanese origin. Berend George Escher introduced it as a geological term in 1922. Description The word ''lahar'' is a general term for a flowing mixture of water and pyroclastic debris. It does not refer to a particular rheology or sediment concentration. Lahars can occur as normal stream flows (sediment concentration of less than 30%), hyper-concentrated stream flows (sediment concentration between 30 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyroclastic Flow
A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of but is capable of reaching speeds up to . The gases and tephra can reach temperatures of about . Pyroclastic flows are the most deadly of all volcanic hazards and are produced as a result of certain explosive eruptions; they normally touch the ground and hurtle downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope. Origin of term The word ''pyroclast'' is derived from the Greek (''pýr''), meaning "fire", and (''klastós''), meaning "broken in pieces". A name for pyroclastic flows which glow red in the dark is (French, "burning cloud"); this was notably used to describe the disastrous 1902 eruption of Mount Pelée on Martinique, a Fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Flow
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is also often called ''lava''. A lava flow is an outpouring of lava during an effusive eruption. (An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. The word ''lava'' comes from Italian and is probably derived from the Latin word ''labe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backcountry Skiing
Backcountry skiing ( US), also called off-piste (Europe), alpine touring, or out-of-area, is skiing in the backcountry on unmarked or unpatrolled areas either inside or outside a ski resort's boundaries. This contrasts with alpine skiing, which is typically done on groomed trails benefiting from a ski patrol. Unlike ski touring, backcountry skiing can include the use of ski lifts including snowcats and helicopters. Recent improvements in equipment have increased the popularity of the sport. Terminology The terms "backcountry" and "off-piste" refer to where the skiing is being done, while terms like ski touring, ski mountaineering, telemark, freeriding, and extreme skiing describe what type of skiing is being done. Terms for backcountry skiing exist according to how the terrain is accessed, and how close it is to services. Backcountry can include the following: * Frontcountry: off-trail within ski area boundaries where ski lifts and emergency services are close at hand. * Slackc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kayaking
Kayaking is the use of a kayak for moving over water. It is distinguished from canoeing by the sitting position of the paddler and the number of blades on the paddle. A kayak is a low-to-the-water, canoe-like boat in which the paddler sits facing forward, legs in front, using a double-bladed paddle to pull front-to-back on one side and then the other in rotation. Most kayaks have closed decks, although sit-on-top and inflatable kayaks are growing in popularity as well. History Kayaks were created thousands of years ago by the Inuit, formerly known as Eskimos, of the northern Arctic regions. They used driftwood and sometimes the skeleton of whale, to construct the frame of the kayak, and animal skin, particularly seal skin was used to create the body. The main purpose for creating the kayak, which literally translates to "hunter's boat" was for hunting and fishing. The kayak's stealth capabilities allowed for the hunter to sneak up behind animals on the shoreline and successful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowshoe Running
Snowshoe running, or snowshoeing, is a winter sport practiced with snowshoes, which is governed by World Snowshoe Federation (WSSF) founded in 2010, which until 2015 had its name International Snowshoe Federation (ISSF). The snowshoes running is part of the Special Olympics and Arctic Winter Games programs. International federations The World Snowshoe Federation (WSSF) is the global governing body of snowshoe running recognized by the International Olympic Committee. World championships WSSF organized the World Snowshoe Championships in 2016 in Vezza d'Oglio, Italy and in 2017 in Saranac Lake, NY from 24 February to 25 February 2017, until the previous edition, the ISSF 2015 World Snowshoe Championships, held in Quebec City, Canada, the championships were organized by the same International federation, but with old name of ISSF. See also *They are also used in winter triathlon *Cross country running * Mountain running *Trail running *Skyrunning Skyrunning is a sport of m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backpacking (wilderness)
Backpacking is the outdoor recreation of carrying gear on one's back, while hiking for more than a day. It is often an extended journey, and may involve camping outdoors. In North America tenting is common, where simple shelters and mountain huts, widely found in Europe, are rare. In New Zealand, hiking is called tramping and tents are used alongside a nationwide network of huts. Hill walking is an equivalent in Britain (but this can also refer to a day walk), though backpackers make use of a variety of accommodation, in addition to camping. Backpackers use simple huts in South Africa. Trekking and bushwalking are other words used to describe such multi-day trips. Backpacking as a method of travel is a different activity, which mainly uses public transport during a journey which can last months. Definition Backpacking is an outdoor recreation where gear is carried in a backpack. This can include food, water, bedding, shelter, clothing, stove, and cooking kit. Given that ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lassen National Forest
Lassen National Forest is a United States national forest of 1,700 square miles (4,300 km2) in northeastern California. It is named after pioneer Peter Lassen, who mined, ranched and promoted the area to emigrant parties in the 1850s. Wildlife Animals that are typically found in this forest are black bear, raccoon, coyote, bobcat, fox, mule deer, skunk, marten, cougar, brown creeper, a variety of chipmunk species, mountain chickadee, a variety of squirrel species, white-headed woodpecker, weasel, a variety of mouse species, long-toed salamander, and a wide variety of bat species. In 2017, three wolf pups were born in this forest. Their mother is a female wolf of unknown origins. Their father is the son of OR7, a wolf with a tracking device that was the first of its kind in almost a century to migrate into California from Oregon. As of July 2020, the pack has 14 members, with 8 new pups. The father of the pups is not related to any of the other California wolves and join ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lassen Volcanic National Park
Lassen Volcanic National Park is an American national park in northeastern California. The dominant feature of the park is Lassen Peak, the largest plug dome volcano in the world and the southernmost volcano in the Cascade Range. Lassen Volcanic National Park is one of the few areas in the world where all four types of volcano can be found—plug dome, shield, cinder cone, and stratovolcano. The source of heat for the volcanism in the Lassen area is subduction of the Gorda Plate diving below the North American Plate off the Northern California coast. The area surrounding Lassen Peak is still active with boiling mud pots, fumaroles, and hot springs. Lassen Volcanic National Park started as two separate national monuments designated by President Theodore Roosevelt in 1907: Cinder Cone National Monument and Lassen Peak National Monument. Starting in May 1914 and lasting until 1917, a series of minor to major eruptions occurred on Lassen. Because of the eruptive activity an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contiguous United States
The contiguous United States (officially the conterminous United States) consists of the 48 adjoining U.S. states and the Federal District of the United States of America. The term excludes the only two non-contiguous states, Alaska and Hawaii (also the last ones admitted to the Union), and all other offshore insular areas, such as American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands. The colloquial term "Lower48" is used also, especially in relation to just Alaska (Hawaii is farther south). The related but distinct term continental United States includes Alaska (which is also on the continent of North America but separated from the 48 states by British Columbia and Yukon of Canada), but excludes the Hawaiian Islands and all U.S. territories in the Caribbean and the Pacific. The greatest distance (on a great-circle route) entirely within the contiguous U.S. is 2,802 miles (4,509 km), between Florida and the State of Washington; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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