Geology Reference
In-Depth Information
8.6.3. Oriented Thaw Lakes
One of the more perplexing aspects of thaw lakes is that they are often elongate in shape,
with a common and systematic orientation of their long axes (Figure 8.11). The thaw lakes
near Point Barrow, northern Alaska, are exceptionally good examples of this phenomenon
(Black and Barksdale, 1949; Carson and Hussey, 1962, 1963; Hinkel et al., 2005). Other
oriented lakes are described from the Beaufort Sea coastal lowlands (Côté and Burn,
2002; Harry and French, 1983; Mackay, 1963), interior Yukon Territory (Price, 1968),
other parts of Arctic Canada (Bird, 1967, pp. 212-216; Dunbar and Greenaway, 1956,
pp. 132-134), and the alluvial coastal lowlands of northern Siberia (Tomirdiaro and
Ryabchun, 1978).
A variety of oriented forms can be recognized. For example, in northern Alaska, the
lakes are commonly elliptical or rectangular in shape, ranging in size from small ponds
to large lakes 15 km long and 6 km wide (Black and Barksdale, 1949; Hinkel et al., 2005).
In Alaska, the ratio of length to breadth varies from 1 : 1 to 1 : 5. Lake depths suggests two
varieties: (a) with a shallow shelf surrounding a deeper central part, which may be 6-10 m
deep, and (b) with a uniform saucer-shaped cross profi le with depths of less than 2 m. In
the Tuktoyaktuk Peninsula of the Mackenzie Delta, numerous oriented lakes are lemnis-
cate, oval, triangular, or elliptical in shape (Mackay, 1963). On southwest Banks Island,
oriented lakes assume a D-shape (Harry and French, 1983) while in western Baffi n Island,
on the Great Plain of Koukdjuak, many thaw lakes are clam-shaped with one straight edge
and with length-breadth ratios varying between 1.5 and 2.5 to 1 (Bird, 1967, p. 215).
Figure 8.11. Vertical air photograph of part of the Sachs River lowlands, southern Banks Island,
Canada, showing elliptical D-shape and preferred orientation of thaw lakes. There are also numer-
ous drained lake basins, one of which contains a small pingo (arrow). Air Photograph A 15980-25,
National Air Photo Library © 1996. Produced under licence from Her Majesty the Queen in Right
of Canada, with permisssion from Natural Resources Canada.
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