Changes in Vegetation Cover of Yukon River Drainages in Interior Alaska: Estimated from MODIS Greenness Trends, 2000 to 2018

The ultramafic rocks in this domain are in the western part of the Brooks Range, the interior Alaska lowlands of the Koyukuk–Yukon Basin, the interior Alaska highlands of the Tanana–Yukon Upland, and the Kuskokwim Mountains. This domain extends east to the Seventymile River, a tributary of the Yukon River that is near the Canadian border, and presumably to the Clinton Creek area in the Yukon Territory. Although the highest elevations in the Brook Range are near 2700 m, those in the western mountains of the range are mostly <1400 m. Flatlands, hills, and low mountains dominate the Koyukuk–Yukon Basin and Tanana–Yukon Uplands, Elevations in the Kuskokwim Mountains are mostly <1000 m. Some of the mountains in uplands of the Tanana–Yukon Uplands are higher than 1600 m. Although the Brooks Range was glaciated during the Pleistocene, there was no glaciation in the Koyukuk–Yukon Basin, and only the higher elevations in the Tanana-Yukon Upland were glaciated during the Quaternary. Today, permafrost prevails throughout the Brooks Range, but it is discontinuous in the Koyukuk–Yukon Basin and Tanana–Yukon Upland and in the Kuskokwim Mountains (Ferrians 1965). Loess is extensive in the basins of interior Alaska and at lower elevations in the Kuskokwim Mountains, with some deposits >60 m thick (Péwé 1975). The climate is very cold throughout the domain, with severe winters and relatively short summers, although mean maximum summer (July) temperatures are >20°C (up to 24°C or 25°C) in the interior basins. With latitudes from 61°N to 68°N, days are very long during summers and very short during winters. The mean annual precipitation is 15–45 cm, with the greatest precipitation during summers. Even though the precipitation is low, the climate is not arid because evapotranspiration is limited by short and relatively cool summers. The freeze-free period is on the order of 60–90 days. The northern and interior Alaska ultramafics (serpentine) consist of Paleozoic and Mesozoic thrust slices emplaced onto Precambrian and Paleozoic marine sediments. They all belong to well-defined belts and are related to low-angle thrust faults or to later high strike–slip faults.

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Two Early Sites of Eastern Beringia: Context and Chronology in Alaskan Interior Archaeology

Radiocarbon ◽

10.1017/s0033822200013199 ◽

1991 ◽

Vol 33 (1) ◽

pp. 35-50 ◽

Cited By ~ 9

Author(s):

Jon Erlandson ◽

Rudy Walser ◽

Howard Maxwell ◽

Nancy Bigelow ◽

John Cook ◽

...

Keyword(s):

American Continent ◽

The West ◽

Hunter Gatherers ◽

Alaska Range ◽

North American Continent ◽

The North ◽

Yukon River ◽

Interior Alaska ◽

Peopling Of The Americas ◽

Early Human

Between the Alaska Range to the south and the Brooks Range to the north, the Yukon River and its tributaries form an extensive network of waterways leading through the lowlands of interior Alaska deep into the North American continent (Fig 1). Despite the extremely cold winters of this arctic and subarctic landscape, much of the region remained unglaciated during the last 50,000 years. The central Alaskan lowlands are at the west end of the “ice-free corridor,” thought by most prehistorians to be the pathway to the Americas for Asian hunter-gatherers crossing the continental Beringian “landbridge.” Until recently, relatively little was known of the early human prehistory of Alaska's interior. Growing interest in the timing, nature and paleoecological context of the initial peopling of the Americas has prompted excavation at a number of early sites in central Alaska and the adjacent Yukon (see Powers & Hamilton 1978; West 1981; Fagan 1987: 119-134; Hamilton 1989; Powers & Hoffecker 1989).

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