Geology Reference
In-Depth Information
Siberian ice sheet. In North America, the Cordilleran, Laurentide, Queen Elizabeth
Islands, and Greenland ice-sheets are recognized.
The largest ice-free areas existed in the western arctic of North America and in eastern
Eurasia. These were joined during the Pleistocene to form an extensive land area known
as Beringia. Remnants of Beringia occur today in central and eastern Siberia, central
Alaska, and northwestern Arctic Canada. Much of the Eurasian portion of Beringia now
lies submerged beneath the Laptev and East Siberian Seas. Not shown in Figure 11.6 is
the sea-ice cover that, presumably, fi lled the Arctic Basin. One must envisage, therefore,
that extensive areas of Beringia consisted of high-latitude tundra and steppe-tundra
terrain that extended northwards to an ice-covered polar ocean. The southern parts of
Beringia would have either bordered the northern Pacifi c Ocean or merged into the inte-
rior steppe-lands of central Asia (Tibet, Kazakhstan, Mongolia, and northeast China). In
North America, a narrow ice-free area of Beringia extended southwards in Central Yukon
Territory and other ice-free areas probably existed in the northern Mackenzie District
and on western Banks Island.
Ice sheets
Beringia and other
areas of continuous
permafrost
Discontinuous
permafrost
180
°
90
°
E
270
°
W
0
°
Figure 11.6.
An overview of the northern hemisphere ice sheets and extent of the periglacial
domain at the height of the last glacial maximum (
∼
18 ka). From CCGM/CGMW-ANDRA (1999)
and other sources mentioned in the text.
