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Double Peak (Alaska)
Double Peak is a prominent 6,818 foot (2,078 meter) mountain summit located in Lake Clark National Park and Preserve, in the Chigmit Mountains of the Aleutian Range, in the US state of Alaska. It is the highest non-volcanic peak in the Chigmit Mountains, and third-highest overall. The mountain is situated immediately north of Double Glacier, west-southwest of Anchorage, and north-northeast of Redoubt Volcano, which is the nearest higher peak. Although modest in elevation, relief is significant since the mountain rises up from tidewater at Cook Inlet in about 20 miles, and it ranks 71st in prominence for all peaks in Alaska. Double Peak was considered to be a volcano by the International Association of Volcanology and Chemistry of the Earth's Interior in 1973, but subsequent reconnaissance mapping indicates the peak is likely made of plutonic rocks of Jurassic age. Published in 1912 by the United States Coast and Geodetic Survey, the mountain takes its name from the Double Glac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chigmit Mountains
The Chigmit Mountains are a subrange of the Aleutian Range in the Kenai Peninsula and Lake and Peninsula Boroughs of the U.S. state of Alaska. Location They are located at the northeastern end of the Aleutian range, on the west side of Cook Inlet, roughly 120 miles (200 km) southwest of Anchorage. The closest major towns to the range are Kenai and Homer, across Cook Inlet on the west side of the Kenai Peninsula. To the north, the Chigmits are bordered by the Tordrillo Mountains, and on the northwest, by the Neacola Mountains. Cook Inlet marks the eastern boundary of the range, while on the west, the mountains fade out into the hills and lowlands of Lake Clark National Park and Preserve. On the south and southwest, the Chigmits abut the continuation of the Aleutian Range into the Alaska Peninsula. Geological composition The Chigmits, along with most of the Aleutian Range, are volcanic, and include two prominent stratovolcanoes, Redoubt Volcano (10,197 feet/3,108 m), t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonic Rock
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March 27, 2017.Igneous intrusive rocks, accessdate: March 27, 2017.Britannica.comintrusive rock , geology , Britannica.com accessdate: March 27, 2017. Intrusion is one of the two ways igneous rock can form. The other is extrusion, such as a volcanic eruption or similar event. An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet. In contrast, an ''extrusion'' consists of extrusive rock, formed above the surface of the crust. Some geologists use the term plutonic rock synonymously with intrusive rock, but other geologists subdivide intrusive rock, by crystal size, into coarse-grained plutonic rock (typically formed deeper in the Earth's crust in batholiths or stocks) an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mountains Of Alaska
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher than a hill, typically rising at least 300 metres (1,000 feet) above the surrounding land. A few mountains are isolated summits, but most occur in mountain ranges. Mountains are formed through tectonic forces, erosion, or volcanism, which act on time scales of up to tens of millions of years. Once mountain building ceases, mountains are slowly leveled through the action of weathering, through slumping and other forms of mass wasting, as well as through erosion by rivers and glaciers. High elevations on mountains produce colder climates than at sea level at similar latitude. These colder climates strongly affect the ecosystems of mountains: different elevations have different plants and animals. Because of the less hospitable terrain and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geography Of Alaska
Alaska occupies the northwestern portion of the North American continent and is bordered only by Canada on the east. It is one of two U.S. states not bordered by another state; Hawaii is the other. Alaska has more ocean coastline than all of the other U.S. states combined. About of Canadian territory separate Alaska from Washington state. Alaska is thus an exclave of the United States that is part of the continental U.S. and the U.S. West Coast, but is not part of the contiguous U.S. Alaska is also the only state, other than Hawaii, whose capital city is accessible only via ship or air, because no roads connect Juneau to the rest of the continent. The state is bordered by Yukon and British Columbia, Canada to the east, the Gulf of Alaska and the Pacific Ocean to the south, Russia ( Chukotka Autonomous Okrug), Bering Sea, the Bering Strait, and Chukchi Sea to the west, and the Beaufort Sea and the Arctic Ocean to the north. Because it extends into the Eastern Hemisphere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Mountain Peaks Of Alaska
This article comprises three sortable tables of major mountain peaksThis article defines a significant summit as a summit with at least of topographic prominence, and a major summit as a susexxleast of topographic prominence. All summits in this article have at least 500 meters of topographic prominence. An ultra-prominent summit is a summit with at least of topographic prominence. of the U.S. State of Alaska. 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.If the elevation or prominence of a summit is calculated as a range of values, the arithmetic mean is shown. The first table below ranks the 100 highest major summits of Alaska by elevation. #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 s ... [...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] |
Cook Inlet
Cook Inlet ( tfn, Tikahtnu; Sugpiaq: ''Cungaaciq'') stretches from the Gulf of Alaska to Anchorage in south-central Alaska. Cook Inlet branches into the Knik Arm and Turnagain Arm at its northern end, almost surrounding Anchorage. On its southern end, it merges with Shelikof Strait, Stevenson Entrance, Kennedy Entrance and Chugach Passage. The Cook Inlet watershed is the most populated watershed in Alaska. The watershed covers about of southern Alaska, east of the Aleutian Range, south and east of the Alaska Range, receiving water from its tributaries, the Knik River, the Little Susitna River, and the Susitna and Matanuska rivers. The watershed includes the drainage areas of Denali (formerly named Mount McKinley). Within the watershed there are several national parks and the active volcano Mount Redoubt, along with three other historically active volcanoes. Cook Inlet provides navigable access to the port of Anchorage at the northern end, and to the smaller Homer port fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subarctic Climate
The subarctic climate (also called subpolar climate, or boreal climate) is a climate with long, cold (often very cold) winters, and short, warm to cool summers. It is found on large landmasses, often away from the moderating effects of an ocean, generally at latitudes from 50° to 70°N, poleward of the humid continental climates. Subarctic or boreal climates are the source regions for the cold air that affects temperate latitudes to the south in winter. These climates represent Köppen climate classification ''Dfc'', ''Dwc'', ''Dsc'', ''Dfd'', ''Dwd'' and ''Dsd''. Description This type of climate offers some of the most extreme seasonal temperature variations found on the planet: in winter, temperatures can drop to below and in summer, the temperature may exceed . However, the summers are short; no more than three months of the year (but at least one month) must have a 24-hour average temperature of at least to fall into this category of climate, and the coldest month should ave ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Köppen Climate Classification
The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notably in 1918 and 1936. Later, the climatologist Rudolf Geiger (1894–1981) introduced some changes to the classification system, which is thus sometimes called the Köppen–Geiger climate classification system. The Köppen climate classification divides climates into five main climate groups, with each group being divided based on seasonal precipitation and temperature patterns. The five main groups are ''A'' (tropical), ''B'' (arid), ''C'' (temperate), ''D'' (continental), and ''E'' (polar). Each group and subgroup is represented by a letter. All climates are assigned a main group (the first letter). All climates except for those in the ''E'' group are assigned a seasonal precipitation subgroup (the second letter). For example, ''Af'' indi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
First Ascent
In mountaineering, a first ascent (abbreviated to FA in guide books) is the first successful, documented attainment of the top of a mountain or the first to follow a particular climbing route. First mountain ascents are notable because they entail genuine exploration, with greater risks, challenges and recognition than climbing a route pioneered by others. The person who performs the first ascent is called the first ascensionist. In free climbing, a first ascent (or first free ascent, abbreviated FFA) of a climbing route is the first successful, documented climb of a route without using equipment such as anchors or ropes for aiding progression or resting. History The details of the first ascents of even many prominent mountains are scanty or unknown; sometimes the only evidence of prior summiting is a cairn, artifacts, or inscriptions at the top. Today, first ascents are generally carefully recorded and usually mentioned in guidebooks. The term is also used when referrin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Coast And Geodetic Survey
The United States Coast and Geodetic Survey (abbreviated USC&GS), known from 1807 to 1836 as the Survey of the Coast and from 1836 until 1878 as the United States Coast Survey, was the first scientific agency of the United States Government. It existed from 1807 to 1970, and throughout its history was responsible for mapping and charting the coast of the United States, and later the coasts of U.S. territories. In 1871, it gained the additional responsibility of surveying the interior of the United States and geodesy became a more important part of its work, leading to it being renamed the U.S. Coast and Geodetic Survey in 1878. Long the U.S. Government's only scientific agency, the Survey accumulated other scientific and technical responsibilities as well, including astronomy, cartography, meteorology, geology, geophysics, hydrography, navigation, oceanography, exploration, pilotage, tides, and topography. It also was responsible for the standardization of weights and measures th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic, Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread Anoxic event, oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar, Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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