A summit is a point on a surface, higher in elevation than all points adjacent to it. The topographic terms acme, apex and zenith are synonymous; the term top is used only for a mountain peak, located at some distance from the nearest point of higher elevation. For example, a big massive rock next to the main summit of a mountain is not considered a summit. Summits near a higher peak, with some prominence or isolation, but not reaching a certain cutoff value for the quantities, are considered subsummits of the higher peak, are considered part of the same mountain. A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top. Summit may refer to the highest point along a line, trail, or route; the highest summit in the world is Everest with height of 8844.43 m above sea level. The first official ascent was made by Sir Edmund Hillary, they reached the mountain`s peak in 1953. Whether a highest point is classified as a summit, a sub peak or a separate mountain is subjective; the UIAA definition of a peak is.
Otherwise, it's a subpeak. In many parts of the western United States, the term summit refers to the highest point along a road, highway, or railroad. For example, the highest point along Interstate 80 in California is referred to as Donner Summit and the highest point on Interstate 5 is Siskiyou Mountain Summit. A summit climbing differs from the common mountaineering. Summit expedition requires: 1+ year of training, a good physical shape, a special gear. Although a huge part of climber’s stuff can be left and taken at the base camps or given to porters, there is a long list of personal equipment. In addition to common mountaineers’ gear, Summit climbers need to take Diamox and bottles of oxygen. There are special requirements for crampons, ice axe, rappel device, etc. Geoid Hill – Landform that extends above the surrounding terrain Nadir Summit accordance Peak finder Summit Climbing Gear List
A caldera is a large cauldron-like hollow that forms following the evacuation of a magma chamber/reservoir. When large volumes of magma are erupted over a short time, structural support for the crust above the magma chamber is lost; the ground surface collapses downward into the emptied magma chamber, leaving a massive depression at the surface. Although sometimes described as a crater, the feature is a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Only seven known caldera-forming collapses have occurred since the start of the 20th century, most at Bárðarbunga volcano in Iceland; the word comes from Spanish caldera, Latin caldaria, meaning "cooking pot". In some texts the English term cauldron is used; the term caldera was introduced into the geological vocabulary by the German geologist Leopold von Buch when he published his memoirs of his 1815 visit to the Canary Islands, where he first saw the Las Cañadas caldera on Tenerife, with Montaña Teide dominating the landscape, the Caldera de Taburiente on La Palma.
A collapse is triggered by the emptying of the magma chamber beneath the volcano, sometimes as the result of a large explosive volcanic eruption, but during effusive eruptions on the flanks of a volcano or in a connected fissure system. If enough magma is ejected, the emptied chamber is unable to support the weight of the volcanic edifice above it. A circular fracture, the "ring fault", develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are known as ring dikes. Secondary volcanic vents may form above the ring fracture; as the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions; the total area that collapses may be thousands of square kilometers. Some calderas are known to host rich ore deposits. One of the world's best-preserved mineralized calderas is the Sturgeon Lake Caldera in northwestern Ontario, which formed during the Neoarchean era about 2,700 million years ago.
If the magma is rich in silica, the caldera is filled in with ignimbrite, tuff and other igneous rocks. Silica-rich magma has a high viscosity, therefore does not flow like basalt; as a result, gases tend to become trapped at high pressure within the magma. When the magma approaches the surface of the Earth, the rapid off-loading of overlying material causes the trapped gases to decompress thus triggering explosive destruction of the magma and spreading volcanic ash over wide areas. Further lava flows may be erupted. If volcanic activity continues, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galán, Lake Toba, etc. by subsequent intrusion of magma. A silicic or rhyolitic caldera may erupt hundreds or thousands of cubic kilometers of material in a single event. Small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction and a noticeable drop in temperature around the world.
Large calderas may have greater effects. When Yellowstone Caldera last erupted some 650,000 years ago, it released about 1,000 km3 of material, covering a substantial part of North America in up to two metres of debris. By comparison, when Mount St. Helens erupted in 1980, it released ~1.2 km3 of ejecta. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia. About 74,000 years ago, this Indonesian volcano released about 2,800 cubic kilometres dense-rock equivalent of ejecta; this was the largest known eruption during the ongoing Quaternary period and the largest known explosive eruption during the last 25 million years. In the late 1990s, anthropologist Stanley Ambrose proposed that a volcanic winter induced by this eruption reduced the human population to about 2,000–20,000 individuals, resulting in a population bottleneck. More Lynn Jorde and Henry Harpending proposed that the human species was reduced to 5,000-10,000 people.
There is no direct evidence, that either theory is correct, there is no evidence for any other animal decline or extinction in environmentally sensitive species. There is evidence. Eruptions forming larger calderas are known La Garita Caldera in the San Juan Mountains of Colorado, where the 5,000 cubic kilometres Fish Canyon Tuff was blasted out in eruptions about 27.8 million years ago. At some points in geological time, rhyolitic calderas have appeared in distinct clusters; the remnants of such clusters may be found in places such as the San Juan Mountains of Colorado or the Saint Francois Mountain Range of Missouri. Some volcanoes, such as the large shield volcanoes Kīlauea and Mauna Loa on the island of Hawaii, form calderas in a different fashion; the magma feeding these volcanoes is basalt, silica poor. As a result, the magma is much less viscous than the magma of a rhyolitic volcano, the magma chamber is drained by large lava flows rather than by explosive events; the resulting calderas are known as subsidence calderas and can form more than explosive calderas.
For instance, the caldera atop Fernandina Island collapsed
Pemberton Volcanic Belt
The Pemberton Volcanic Belt is an eroded Oligocene-Miocene volcanic belt at a low angle near the Mount Meager massif, British Columbia, Canada. The Garibaldi and Pemberton volcanic belts appear to merge into a single belt, although the Pemberton is older than the Garibaldi Volcanic Belt; the Pemberton Volcanic Belt is one of the geological formations comprising the Canadian Cascade Arc. It formed as a result of subduction of the former Farallon Plate. Features within the Pemberton Belt include: Mount Barr Plutonic Complex Mount Barr Chilliwack batholith Slesse Mountain Chipmunk Mountain 50°34′49.87″N 122°55′56.47″W Coquihalla Mountain 49°31′30.0″N 121°03′36.0″W Crevasse Crag Franklin Glacier Complex Salal Creek Pluton Silverthrone Caldera Garibaldi Volcanic Belt Geology of the Pacific Northwest Cascade Volcanoes Volcanism of Canada Volcanism of Western Canada Canada Volcanoes and Volcanics USGS
Yukon is the smallest and westernmost of Canada's three federal territories. It has the smallest population of any province or territory in Canada, with 35,874 people, although it has the largest city in any of the three territories. Whitehorse is Yukon's only city. Yukon was split from the Northwest Territories in 1898 and was named the Yukon Territory; the federal government's Yukon Act, which received royal assent on March 27, 2002, established Yukon as the territory's official name, though Yukon Territory is still popular in usage and Canada Post continues to use the territory's internationally approved postal abbreviation of YT. Though bilingual, the Yukon government recognizes First Nations languages. At 5,959 m, Yukon's Mount Logan, in Kluane National Park and Reserve, is the highest mountain in Canada and the second-highest on the North American continent. Most of Yukon has a subarctic climate, characterized by brief warm summers; the Arctic Ocean coast has a tundra climate. Notable rivers include the Yukon River, as well as the Pelly, Peel and Tatshenshini rivers.
The territory is named after the longest river in Yukon. The name itself is from a contraction of the words in the Gwich'in phrase chųų gąįį han, which means white water river and refers to "the pale colour" of glacial runoff in the Yukon River. Long before the arrival of Europeans and southern Yukon was populated by First Nations people, the area escaped glaciation. Sites of archeological significance in Yukon hold some of the earliest evidence of the presence of human habitation in North America; the sites safeguard the earliest First Nations of the Yukon. The volcanic eruption of Mount Churchill in 800 AD in what is now the U. S. state of Alaska blanketed southern Yukon with a layer of ash which can still be seen along the Klondike Highway, which forms part of the oral tradition of First Nations peoples in Yukon and further south in Canada. Coastal and inland First Nations had extensive trading networks. European incursions into the area began early in the 19th century with the fur trade, followed by missionaries.
By the 1870s and 1880s gold miners began to arrive. This drove a population increase that justified the establishment of a police force, just in time for the start of the Klondike Gold Rush in 1897; the increased population coming with the gold rush led to the separation of the Yukon district from the Northwest Territories and the formation of the separate Yukon Territory in 1898. The territory is the approximate shape of a right triangle, bordering the U. S. state of Alaska to the west and northwest for 1,210 km along longitude 141° W, the Northwest Territories to the east and British Columbia to the south. Its northern coast is on the Beaufort Sea, its ragged eastern boundary follows the divide between the Yukon Basin and the Mackenzie River drainage basin to the east in the Mackenzie mountains. Most of the territory is in the watershed of the Yukon River; the southern Yukon is dotted with a large number of large and narrow glacier-fed alpine lakes, most of which flow into the Yukon River system.
The larger lakes include Teslin Lake, Atlin Lake, Tagish Lake, Marsh Lake, Lake Laberge, Kusawa Lake and Kluane Lake. Bennett Lake on the Klondike Gold Rush trail is a lake flowing into Nares Lake, with the greater part of its area within Yukon. Canada's highest point, Mount Logan, is in the territory's southwest. Mount Logan and a large part of Yukon's southwest are in Kluane National Park and Reserve, a UNESCO World Heritage Site. Other national parks include Ivvavik National Vuntut National Park in the north. Other watersheds include the Mackenzie River, the Peel Watershed and the Alsek–Tatshenshini, a number of rivers flowing directly into the Beaufort Sea; the two main Yukon rivers flowing into the Mackenzie in the Northwest Territories are the Liard River in the southeast and the Peel River and its tributaries in the northeast. Notable widespread tree species within Yukon are white spruce. Many trees are stunted because of severe climate; the capital, Whitehorse, is the largest city, with about three-quarters of the population.
British Columbia Northwest Territories Alaska, United States While the average winter temperature in Yukon is mild by Canadian arctic standards, no other place in North America gets as cold as Yukon during extreme cold snaps. The temperature has dropped down to −60 °C three times, 1947, 1954, 1968; the most extreme cold snap occurred in February 1947 when the abandoned town of Snag dropped down to −63.0 °C. Unlike most of Canada where the most extreme heat waves occur in July and September, Yukon's extreme heat tends to occur in June and May. Yukon has recorded 36 °C three times; the first time was in June 1969 when Mayo recorded a temperature of 36.1 °C. 14 years this record was beaten when Forty Mile recorded 36 °C in May 1983. The old record was broken 21 years in June 2004 when the Mayo Road weather station, located just northwest of Whitehorse, recorded a temperature of 36.5 °C. The 2016 census reported a Yukon population of 35,874, an increase of 5.8% from 2011. With a land area of 474,712.64 km2, it had a population de
The Ha-Iltzuk Icefield is an icefield in the central Pacific Ranges of the Coast Mountains in British Columbia, Canada. It is the largest icefield in the Coast Mountains south of the Alaska Panhandle, with an area of 3,610 km2, it is located on the west side of the Waddington Range. The highest summit in the icefield is Mount Silverthrone, a mountain on the northeast edge of a circular, 20 km wide dissected caldera complex called the Silverthrone Caldera; the southern half of the icefield is named the Silverthrone Glacier and flows west, joining the Klinaklini Glacier just above that glacier's terminus, where its outflow is short but large, joins the Klinaklini River within a few kilometres. The Klinaklini Glacier constitutes the northern half of the icefield, off its northwest edge a glacial tongue produces the head of the Machmell River; the name Ha-Iltzuk Icefield does not appear in government gazettes. The term is certainly a phonetic spelling of hailtzaq - the Heiltsuk language pronunciation for the term Heiltsuk.
Heiltsuk List of glaciers Pacific Ranges Lillooet Icecap Homathko Icefield
Granite is a common type of felsic intrusive igneous rock, granular and phaneritic in texture. Granites can be predominantly white, pink, or gray depending on their mineralogy; the word "granite" comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a holocrystalline rock. Speaking, granite is an igneous rock with between 20% and 60% quartz by volume, at least 35% of the total feldspar consisting of alkali feldspar, although the term "granite" is used to refer to a wider range of coarse-grained igneous rocks containing quartz and feldspar; the term "granitic" means granite-like and is applied to granite and a group of intrusive igneous rocks with similar textures and slight variations in composition and origin. These rocks consist of feldspar, quartz and amphibole minerals, which form an interlocking, somewhat equigranular matrix of feldspar and quartz with scattered darker biotite mica and amphibole peppering the lighter color minerals; some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic.
A granitic rock with a porphyritic texture is known as a granite porphyry. Granitoid is a descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids; the extrusive igneous rock equivalent of granite is rhyolite. Granite is nearly always massive and tough; these properties have made granite a widespread construction stone throughout human history. The average density of granite is between 2.65 and 2.75 g/cm3, its compressive strength lies above 200 MPa, its viscosity near STP is 3–6·1019 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C. Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present. Granite is classified according to the QAPF diagram for coarse grained plutonic rocks and is named according to the percentage of quartz, alkali feldspar and plagioclase feldspar on the A-Q-P half of the diagram.
True granite contains both alkali feldspars. When a granitoid is devoid or nearly devoid of plagioclase, the rock is referred to as alkali feldspar granite; when a granitoid contains less than 10% orthoclase, it is called tonalite. A granite containing both muscovite and biotite micas is called two-mica granite. Two-mica granites are high in potassium and low in plagioclase, are S-type granites or A-type granites. A worldwide average of the chemical composition of granite, by weight percent, based on 2485 analyses: Granite containing rock is distributed throughout the continental crust. Much of it was intruded during the Precambrian age. Outcrops of granite tend to form rounded massifs. Granites sometimes occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels. Granite occurs as small, less than 100 km2 stock masses and in batholiths that are associated with orogenic mountain ranges. Small dikes of granitic composition called aplites are associated with the margins of granitic intrusions.
In some locations coarse-grained pegmatite masses occur with granite. Granite is more common in continental crust than in oceanic crust, they are crystallized from felsic melts which are less dense than mafic rocks and thus tend to ascend toward the surface. In contrast, mafic rocks, either basalts or gabbros, once metamorphosed at eclogite facies, tend to sink into the mantle beneath the Moho. Granitoids have crystallized from felsic magmas that have compositions near a eutectic point. Magmas are composed of minerals in variable abundances. Traditionally, magmatic minerals are crystallized from the melts that have separated from their parental rocks and thus are evolved because of igneous differentiation. If a granite has a cooling process, it has the potential to form larger crystals. There are peritectic and residual minerals in granitic magmas. Peritectic minerals are generated through peritectic reactions, whereas residual minerals are inherited from parental rocks. In either case, magmas will evolve to the eutectic for crystallization upon cooling.
Anatectic melts are produced by peritectic reactions, but they are much less evolved than magmatic melts because they have not separated from their parental rocks. The composition of anatectic melts may change toward the magmatic melts through high-degree fractional crystallization. Fractional crystallisation serves to reduce a melt in iron, titanium and sodium, enrich the melt in potassium and silicon – alkali feldspar and quartz, are two of the defining constituents of granite; this process operates regardless of the origin of parental magmas to granites, regardless of their chemistry. The composition and origin of any magma that differentiates into granite leave certain petrological evidence as to what the granite's parental rock was; the final texture and composition of a granite are distinctive as to its parental rock. For instance, a granite, derived from partial melting of meta
Coast Range Arc
The Coast Range Arc was a large volcanic arc system, extending from northern Washington through British Columbia and the Alaska Panhandle to southwestern Yukon. The Coast Range Arc lies along the western margin of the North American Plate in the Pacific Northwest of western North America. Although taking its name from the Coast Mountains, this term is a geologic grouping rather than a geographic one, the Coast Range Arc extended south into the High Cascades of the Cascade Range, past the Fraser River, the northward limit of the Cascade Range proper; the Coast Range Arc formed as a result of subduction of the pre-existing Farallon Plates. It is most famous for being the largest granitic outcropping in North America, which it is referred to as the Coast Plutonic Complex or the Coast Mountains Batholith, it is a coast-parallel continental volcanic arc similar to the Andes of South America and the largest continental volcanic arc fossil in the world. Volcanism in the arc began during the Late Cretaceous period 100 million years ago based on andesitic composition of the Early Cretaceous volcanic sections and their close temporal and spatial association with masses of felsic intrusive igneous rock with phaneritic texture called tonalite.
The basement of the Coast Range Arc was Early Cretaceous and Late Jurassic intrusions. Stratigraphic and field relations in the arc suggest that the Coast Range Arc was created on Stikinia, a geologic feature that formed in an older volcanic arc environment during the Paleozoic and Mesozoic periods. One of the major events during the Coast Range Arc was about 85 million years ago when a huge rift developed near the center of the oceanic Farallon Plate; this rifting event created the oceanic Kula Plate. It is unknown; some geologists believe some fundamental change in convection within the Earth's mantle caused the rifting event, while others believe the huge oceanic plate became mechanically unstable as it continued to subduct beneath the Pacific Northwest. The Kula Plate once again continued to subduct beneath the continental margin, supporting the Coast Range Arc. Volcanism began to decline along the length of the arc about 60 million years ago during the Albian and Aptian faunal stages of the Cretaceous period as the rapid northern movement of the Kula Plate became parallel with the Pacific Northwest, creating a transform fault plate boundary similar to the Queen Charlotte Fault.
During this passive plate boundary, the Kula Plate began subducting underneath Alaska and southwestern Yukon at the northern end of the arc during the early Eocene period. The Coast Range Arc was home to some of the world's most explosive volcanoes. Cataclysmic eruptions at the British Columbia–Yukon border created a huge nested caldera called the Bennett Lake Volcanic Complex about 50 million years ago during the early Eocene period; these eruptions were from vents along arcuate fracture systems associated with the caldera, which discharged about 850 cubic kilometres of pyroclastic material. This volcanic event occurred shortly before nearly all the Kula Plate had been subducted beneath the North American Plate about 40 million years ago. Since the end of the Coast Range Arc about 50 million years ago, many volcanoes have disappeared from erosion. What remains of the Coast Range Arc to this day are granitic intrusions, which were formed when magma intruded and cooled at depth beneath the volcanoes.
However, remnants of some volcanoes exist in southwestern Yukon, including Montana Mountain, Mount Nansen, the Bennett Lake, Mount Skukum and Sifton Range volcanic complexes. Many granitic rocks of the Coast Range Arc are plentiful in the North Cascades of the Cascade Range, the southernmost boundary of the arc. Here, these granites intruded deformed ocean rocks and assorted fragments from pre-existing island arcs remnants of the ancient Bridge River Ocean which lay between North America and the pre-existing Insular Islands. Massive amounts of molten granite injected over this period, burning the old oceanic sediments into a glittering medium-grade metamorphic rock called schist; the older intrusions of the Coast Range Arc were deformed under the heat and pressure of intrusions, turning them into a layered metamorphic rock known as gneiss. In some places, mixtures of older intrusive rocks and the original oceanic rocks have been distorted and warped under intense heat and stress to create unusual swirled patterns known as migmatite, appearing to have been nearly melted in the procedure.
The remarkable migmatite of the Chelan and Skagit areas in Washington are well known in geologic circles. During construction of intrusions 70 and 57 million years ago, the northern motion of the Kula Plate might have been between 140 and 110 millimetres per year. However, other geologic studies determined the Kula Plate moved at a rate as fast as 200 millimetres per year. Intrusions of the Coast Range Arc are intruded by widespread basaltic dikes; these dikes, although not voluminous, provide an important sampling of the post-arc lithosphere. Additionally, widespread volcanic belts, such as the Anahim Volcanic Belt, lie in the middle of the Coast Range Arc. Volcanics that form the Anahim Volcanic Belt are not related to Coast Range Arc subduction, but might have formed as a result of the North American Plate sliding over a place that has experienced active volcanism for a long period of time, described as the Anahim hotspot. During its formation, it lay beneath granitic intrusions of the Coast Range Arc.
The 20-kilometre long Bella Bella and 6-kilometre long Gale Passage dike swarms lie in granitic intrusions of the Coast Range Arc and are used to calculat