Charles Storrow Denny
1952
<p><span>Reconnaissance field work </span>along<span> the </span>Alaska<span> </span>Highway<span> in </span>northern<span> </span>British<span> </span>Columbia<span> and </span>southeastern<span> </span>Yukon<span> furnishes preliminary data on the later </span>Quaternary<span> history of the region, and on the processes and results of intensive </span>frost<span> action. Extensive erosion surfaces were developed prior to glaciation, such as the Alberta Plateau of northeastern </span>British<span> </span>Columbia<span> and the </span>Yukon<span> Plateau in southern </span>Yukon<span>. In the region from Dawson Creek to Fort Nelson, </span>British<span> </span>Columbia<span>, the drift is dominantly a slightly weathered bouldery clay till of Wisconsin age, deposited by ice that came from the east. In the </span>northern<span> Rocky Mountains, the last eastward advance of the Wisconsin glaciers to the mountain front preceded the maximum westward advance of the ice sheets. In the foothills belt west of the </span>Highway<span>, the tills of these two advances are separated by lake deposits. Much of the drift is probably pre-Altamont in age and was subjected to vigorous </span>frost<span> action during the Altamont substage. The climate ameliorated perhaps with the advent of the post-glacial optimum and possibly coincident with the development of prairies. A recent change from prairie to forest perhaps indicates a slight cooling in recent time. In the </span>northern<span> Rocky Mountains, four substages of Wisconsin glaciation are recognized tentatively on the basis of morainal deposits and outwash terraces. The upper Liard basin is characterized by extensive pitted outwash plains, probably of </span>late<span> Wisconsin age. From Teslin Lake to Whitehorse, the </span>Highway<span> is bordered by extensive terraces of gravel and sand deposited in ice-marginal streams and lakes. Intensive </span>frost<span> action has modified pre-existing land forms and has produced a wide variety of features, such as talus, blockfields, stone rings, stone stripes, and terraces. Long smooth slopes, chiefly due to mass movements such as solifluction, are characteristic of the landscapes. These slopes and ancient soil structures extend down into forested areas and probably developed prior to the advent of forests, doubtless prior to the post-glacial optimum. </span>Phenomena<span> resulting from intensive </span>frost<span> action at the present time are restricted largely to areas above timber line. </span></p>
application/pdf
10.1130/0016-7606(1952)63[883:LQGAFP]2.0.CO;2
en
Geological Society of America
Late quaternary geology and frost phenomena along Alaska Highway, Northern British Columbia and Southeastern Yukon
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