DEFINITION OF NORTH SLOPE OF ALASKA AND ANWR

The Brooks Range of northern Alaska gradually diminishes northward, sloping

toward the Beaufort Sea along the North Slope coastal plain.

The region referred to as the North Slope stretches from the

Yukon border in the British and Romanzof Mountains, stretches

west past Prudhoe Bay and Deadhorse, past Barrow, and to

Point Lay and Cape Lisburne on the Chukchi Sea. This arctic

coastal plain and mountainous area is one of the last large relatively

untouched wilderness areas in the United States, and constant

battles are fought between environmentalists who would

like to preserve the area’s pristine state and proponents of the

petroleum industry who would like to see additional petroleum

exploration, especially in the Arctic National Wildlife Refuge

(ANWR) in the eastern part of the plain. This region is continuous

with the petroleum-rich Prudhoe Bay area and may contain

large reserves of oil. The region is the summer home and breeding

grounds for herds of caribou, bears, and many other species

of animals. In 2005 Congress approved legislation allowing

exploration for petroleum in ANWR.

Paleozoic rocks of the Brooks Range are separated from

Mesozoic rocks of the foothills by a major imbricate fault

zone. Along this zone, many east-west striking faults dip south

under the Brooks Range, and folds are overturned toward the

north (and dip south by 20°–40°). Many minor thrust faults

are present in the contact zone between the Brooks Range and

foothills, with the thrust faults becoming steeper toward the

Brooks Range in the south. Displacements on the faults range

up to several thousand feet (hundreds of meters).

The southern foothills are located just north of the Brooks

Range and include mainly Mesozoic rocks that are folded but

rarely faulted, forming elongate rolling hills. Many of the folds

have steep northern limbs and shallow-dipping southern limbs,

indicating they formed by northward tectonic movements.

Thick units exhibit long-wavelength parallel folds, while thin

units show small tight folds. Some of the folds are cored and cut

by minor thrust faults. The southern foothills grade into the

northern foothills, characterized by laterally persistent anticlines,

some of which bifurcate and separate canoe-shaped synclines.

There is a nearly constant distance of 7 miles (11 km) between

the crests of adjacent anticlines. Dips on the limbs of the folds

range between 6° and 20°, and there is a gradual northward

decrease in the amplitude of the folds, and in the number of

faults cutting the section. The region is cut by several northnortheast

striking faults that show strike-slip displacements and

are probably tear faults related to northward thrusting and folding,

with differential movement between blocks on either side of

the faults. These faults control the courses of several of the

major rivers in the area.

The Arctic Foothills province grades north into the Arctic

Coastal Plain province. North of about 70° latitude, the

beds become largely flat-lying, and the surface is covered by

permafrost and tundra. The eastern part of this region was

designated as the Arctic National Wildlife Refuge in 1960 by

the secretary of the interior, including about 13,000 square

miles (21,000 km2) inhabited by grizzlies, caribou, dall sheep,

and millions of migratory birds. The Arctic National Wildlife

Refuge is the largest wildlife refuge in the United States, and

the only refuge in the Arctic. The mission of the refuge is to

preserve the flora and fauna of the Arctic in its natural state.

It will be a daunting task for oil companies to meet this mission

while exploring for and extracting oil to meet America’s

energy needs.

See also BROOKS RANGE; TAIGA; TUNDRA.

Title Post:
Rating: 100% based on 99998 ratings. 99 user reviews.
Author:

Terimakasih sudah berkunjung di blog SELAPUTS, Jika ada kritik dan saran silahkan tinggalkan komentar