DENALI NATIONAL PARK – #FINDYOURPARK FRIDAY


Denali-National-Park-17-Wallpaper-HD


DENALI NATIONAL PARK
Near the geographic center of Alaska, Denali National Park and Preserve surrounds Mount McKinley, which hinges the great arc of the Alaska Range. The mountain, called Denali— The High One—by neighboring Athabaskan Indians, soars more than 20,300 feet above the sea, highest of North American peaks. It dominates its 12,400-foot consort and the lesser
elevations of the range as a monarch commands his court.

From the mountain’s high buttresses and perpetual ice fields glaciers descend radially, sculpting great gorges in the granite and sediments of the massif. Then the landscape falls away through barren rock canyons to lake-dotted tundra benches and, finally, to wide valleys formed by turbid glacial rivers, their braided beds flanked by stands of boreal forest.
On these lowlands more than 3 miles below the banner mountain, backdropped by the farstretching range, roams a panoply of wildlife: caribou, bear, moose, wolf, fox, and, on the lower crags, the white mountain sheep of the north. In summer the animals blend into folds of
landscape, moss-floored forest, and distant tundra moors. As migratory bands, as packs and family groups, or as solitaries, they forage the slopes and stream courses, building the reserves of fat to carry them through winter.

From earliest times, for at least 11 millennia, humans have been seasonally attracted to this remote and elevated country because of the concentrations of game animals. The migratory bands of caribou and sheep, the numerous moose and bear, and, in those earliest times, the relict bison and elk at the end of the last great ice age, have spurred human migration to the Denali region despite its isolation and forbidding terrain. In traditional times, a century and more ago, the people came from camps and villages on the many rivers fed by Denali’s glaciers: Susitna, Chulitna, Kahiltna, Yentna flowing south; Kuskokwim flowing southwest; Kantishna, Toklat, Teklanika, Nenana flowing north. Some of the hunters cut the arc of the Alaska Range, travelling westward 200 miles from the Copper River basin. Others congregated from the Tanana or portaged from the Yukon. These people came to hunt the high, sparsely forested slopes and valleys and the funneling narrows of the passes. They came by boat as far as shoaling streams allowed, then overland to the killing sites. After the hunt, their meat and skins in tow, they left Denali’s shelterless flanks and returned to the forested lands of the big rivers where logs for building and fuel, and migrating salmon for sustaining food, allowed survival through winter darkness and cold.

Migrations continue to this day. The animals still band together for their seasonal convocations. And people come from afar to behold this recurrent display of wildlife posed against the mountain. The great difference from the primeval scene is the migrant humans. Today, except on the fringes of the recently expanded parkland, they hunt with spotting scope and camera. It was this gathering of wildlife, and fear that market hunting would destroy it, that inspired hunter-naturalist Charles Sheldon in the early years of this century. After extended visits to the Denali region in the years 1906-08, he turned his concerns into a vision: a park-refuge where Denali’s vulnerable concentrations of game animals could roam and propagate unhunted—a reservoir that upon overflow would populate surrounding areas to the benefit of isolated mining camps and communities dependent on wild meat. He saw the fulfilling combination of protected wildlife and magnificent mountain scenery as a lure to visitors who would benefit the economy and development of Alaska.

After a decade of tireless efforts, Sheldon and the cohort of individuals and organizations that followed his lead joined with officials of the newly established National Park Service at the first National Parks Conference in January 1912, just weeks before Congress passed the Mount McKinley National Park establishment act.

Sheldon’s vision of a park-refuge where visitors could view plentiful wildlife against the backdrop of stupendous mountains shaped the park’s founding legislation; it inspired the policies and practices of the new park’s first stewards and their successors through the years; it still determines the management philosophy and the visitor expectations of the expanded
Denali National Park and Preserve created by Congress in 1980.
The relationship between Denali’s mountains, wildlife, and people has changed drastically through the millennia that separate the ancient hunting parties and last summer’s park visitors. In those first days remote geography and mountain ranges translated into time-and-energy barriers that hunters overcame in the quest for game. Today, modern transportation transforms distance into minutes and mountain barricades into scenery. The park ideal changed game into wildlife—the living adornment that, in Sheldon’s synthesis, makes the scenery complete. These evolutions of human action and ideal, from traditional times to the present, form the backbone of the history that follows. [1]

GEOLOGICAL HISTORY
Denali National Park and Preserve is located in the central area of the Alaska Range, a mountain chain extending 600 miles (970 km) across Alaska. Its best-known geologic feature is Mount McKinley, also known by its Athabascan name of Denali. Its elevation of 20,237 feet (6,168 m) makes it the highest mountain in North America. Its vertical relief (distance from base to peak) of 18,000 feet (5,500 m) is the highest of any mountain in the world. The mountain is still gaining about 1 millimetre (0.039 in) in height each year due to the continued convergence of the North American and Pacific Plates. The mountain is primarily made of granite, a hard rock that does not erode easily; this is why it has retained such a great height rather than being eroded.

There are three major rock provinces that run in east-west bands through the park. The oldest is in the north, and the younger ones in the south. The area is characterized by collision tectonics: over the past millions of years, exotic terranes in the Pacific Ocean have been moving toward the North American landmass and accreting, or attaching, to the area that now makes up Alaska.

The oldest rocks in the park are part of the Yukon-Tanana terrane. They originated from ocean sediments deposited between 400 million and 1 billion years ago. The original rocks have been affected by the processes of regional metamorphism, folding, and faulting to form rocks such as schist, quartzite, phyllite, slate, marble, and limestone.

The next oldest group of rocks is the Farewell terrane. It is composed of rocks from the Paleozoic era (250-500 million years old). The sediments that make up these rocks were deposited in a variety of marine environments, ranging from deep ocean basins to continental shelf areas. The abundant marine fossils are evidence that around 380 million years ago, this area had a warm, tropical climate.

The Pingston, McKinley, and Chulitna terranes are the next oldest; they were deposited in the Mesozoic era. The rock types include marble, chert, limestone, shale, and sandstone. There are intrusions of igneous rocks, such as gabbro, diabase, and diorite. Special features include pillow basalts, which are formed when molten lava flows into water and a hard outer crust forms, making a puffy, pillow shaped feature; as well as an ophiolite sequence, which is a distinct sequence of rocks indicating that a section of oceanic crust has been uplifted and thrust onto a continental area.

Some of the youngest rocks in the park include the Kahlitna terrane, which is a flysch sequence (a sedimentary rock sequence deposited in a marine environment during the early stages of mountain building) formed about 100 million years ago, during late Cretaceous time. Another rock sequence is the McKinley Intrusive Sequence, which includes Mount McKinley. The Cantwell Volcanics include basalt and rhyolite flows, as well as ash deposits. An example can be seen at Polychrome Pass in the park.

Denali National Park and Preserve is located in an area of intense tectonic activity: the Pacific Plate is subducting under the North American plate, creating the Denali fault system, which is a right-lateral strike-slip fault over 720 miles (1,160 km) long. This is a part of the larger fault system which includes the famous San Andreas Fault of California. Over 600 earthquakes occur in the park each year, helping seismologists to understand this fault system. Most of these earthquakes are too small to be felt, although two large earthquakes did occur in 2002. On October 23, 2002 a magnitude 6.7 earthquake occurred in the park, and on November 3, 2002, a magnitude 7.9 earthquake occurred. These earthquakes did not cause a significant loss of life or property, since the area is very sparsely populated, but they did trigger thousands of landslides. [3]

RESOURCES:
[1] A History of the Denali-Mount McKinley Region – https://s3.amazonaws.com/storyofwhere/doc/state/ak/Brown1991_HRSHistoryDenali.pdf
[2] History of the Denali Mount McKinley Region – https://data.doi.gov/dataset/a-history-of-the-denali-mount-mckinley-region-alaska-historic-resource-study-of-denali-nat
[3] Denali National Park and Preserve, https://en.wikipedia.org/w/index.php?title=Denali_National_Park_and_Preserve&oldid=673436014 (last visited Aug. 5, 2015).