Brooks Range

Brooks Range

Brooks Range from near Galbraith Lake
Highest point
Peak Mount Isto
Elevation 8,976 ft (2,736 m)
Coordinates 69°16′39″N 144°54′40″W / 69.27750°N 144.91111°W / 69.27750; -144.91111
Dimensions
Length 700 mi (1,100 km) East-west
Width 150 mi (240 km) North-south
Geography
Countries United States and Canada
States/Provinces Alaska and Yukon
Range coordinates 68°12′N 152°15′W / 68.2°N 152.25°W / 68.2; -152.25Coordinates: 68°12′N 152°15′W / 68.2°N 152.25°W / 68.2; -152.25
Geology
Orogeny Laramide
Age of rock Cretaceous

The Brooks Range (Athabaskan Gwazhał[1]) is a mountain range in far northern North America stretching some 700 miles (1,100 km) from west to east across northern Alaska into Canada's Yukon Territory. Reaching a peak elevation of 8,976 feet (2,736 m) on Mount Isto, the range is believed to be approximately 126 million years old.

In the United States, these mountains are considered an extension of the Rocky Mountains, whereas in Canada they are considered separate, the northern border of the Rocky Mountains regarded as the Liard River far to the south in the province of British Columbia.[2][3]

While the range is mostly uninhabited, the Dalton Highway and Trans-Alaska Pipeline System run through the Atigun Pass (1,415 m, 4,643 ft) on their way to the oil fields at Prudhoe Bay on Alaska's North Slope. The Alaska Native villages of Anaktuvuk and Arctic Village, as well as the very small communities of Coldfoot, Wiseman, Bettles, and Chandalar Lake, are the range's only settlements. In the far west, near the Wulik River in the De Long Mountains is the Red Dog mine, largest zinc mine in the world.

The range was named by the United States Board on Geographic Names in 1925 after Alfred Hulse Brooks, chief USGS geologist for Alaska from 1903 to 1924.

Various historical records also referred to the range as the Arctic Mountains, Hooper Mountains, Meade Mountains and Meade River Mountains; the Canadian portion is still often referred to as the British Mountains, a part of Ivvavik National Park.

Peaks

Brooks Range Mountains
Limestack Mountain, a tall limestone fin with sheer cliffs in the central Brooks Range
Limestack Mountain, in the central Brooks Range

Ecology

Area of the Arctic National Wildlife Refuge coastal plain, looking south toward the Brooks Range

The Brooks Range forms the northernmost drainage divide in North America, separating streams flowing into the Arctic Ocean and the North Pacific. The range roughly delineates the summer position of the Arctic front. It represents the northern extent of the tree line, with little beyond isolated Balsam poplar stands occurring north of the continental drainage divide. Trembling aspen and white spruce also occur north of the Brooks Range, though they are limited to sites that have been disturbed by human activity.[4][5] Southern slopes have some cover of Black Spruce, Picea mariana, marking the northern limit of those trees.[6] As one of the most remote and least-disturbed wildernesses of North America, the mountains are home to Dall sheep, grizzly bears, and caribou.

In Alaska, the 490,000 animal strong (in 2004) Western Arctic Caribou herd traverses the Brooks Range in its annual migration. The smaller Central Arctic herd (32,000 in 2002), as well as the 123,000 animal Porcupine Caribou herd, likewise migrate through the Brooks range on their annual journeys in and out of the Arctic National Wildlife Refuge. The migration path of the Porcupine Caribou Herd is the longest of any terrestrial mammal on earth.

Paleontology

Fossil corals in the Brooks Range
Fossilized corals in the Brooks Range, near Limestack Mountain

Because it is heavily composed of ancient seabed, the Brooks Range contains ancient marine and other fossils. In addition to the coral fossils shown at left, trilobites and brachiopods from the middle Cambrian have been found in the sandy limestones of the Central Brooks Range.[7]

Climate

While other Alaskan ranges to the south and closer to the coast can receive 250 inches (640 cm) to 500 inches (1,300 cm) of snow, the average snow precipitation on the Brooks Range is reported at 30 inches (76 cm)[8] to 51 inches (130 cm).[9]

As measured at the Anaktuvuk Pass weather station (elevation 770 metres (2,530 ft)), the average summer temperatures are 3 °C (37 °F) as a low and 16 °C (61 °F) as a high. During the winter the average low is −30 °C (−22 °F) while the average high is −22 °C (−8 °F).[9]

Films

See also

Notes

  1. ↑ USGS
  2. ↑ The Encyclopedia Americana, Volume 23, page 618 (Grolier 2000).
  3. ↑ Safire, William. The New York Times guide to essential knowledge: a desk reference for the curious mind, page 623 (Macmillan 2007 ).
  4. ↑ Ackerman, Daniel; Breen, Amy (2016-06-06). "Infrastructure Development Accelerates Range Expansion of Trembling Aspen ( Populus tremuloides , Salicaceae) into the Arctic". ARCTIC. 69 (2): 130–136. doi:10.14430/arctic4560. ISSN 1923-1245.
  5. ↑ Elsner, Wendy K.; Jorgenson, Janet C. (2009-09-11). "White Spruce Seedling ( Picea glauca ) Discovered North of the Brooks Range Along Alaska's Dalton Highway". ARCTIC. 62 (3): 342–344. doi:10.14430/arctic155. ISSN 1923-1245.
  6. ↑ C. Michael Hogan, Black Spruce: Picea mariana, GlobalTwitcher.com, ed. Nicklas Stromberg, November, 2008 Archived October 5, 2011, at the Wayback Machine.
  7. ↑ J.T. Dutro et al, November 1984, "Middle Cambrian Fossils from the Doonerak Anticlinorium, Central Brooks Range, Alaska", Journal of Paleontology Vol. 58 No. 6, pages 1364-1371
  8. ↑ Shulski, Martha; Wendler, Gerd (2007-12-15). The Climate of Alaska. University of Alaska Press. pp. 148–. ISBN 9781602230071. Retrieved 16 December 2012.
  9. 1 2 Gallant, Alisa L. (1998-05-01). EcoRegions of Alaska. DIANE Publishing. pp. 15–. ISBN 9780788148965. Retrieved 16 December 2012.

Further reading

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