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Surficial Geology

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Yukon has a fascinating Quaternary history. Since the onset of Pleistocene glaciations, approximately 2.6 million years ago, large portions of the territory have been covered by the Cordilleran ice sheet. The ice sheet was composed of quasi-independent lobes that were centered in southern and eastern Yukon. Each of these lobes has its own history and responded differently to climate forcings. Throughout most of Yukon, the late Wisconsin-McConnell glaciation was less extensive than some previous glaciations. The age of these older, more extensive glaciation(s), varies and is an important topic in Yukon Quaternary geology.

The ice sheet limits in Yukon form the eastern boundary of Beringia, the ice-free region that extended westward into Alaska and Siberia. Unglaciated terrain has a very different geomorphology compared to the glaciated regions and it is also home to the majority of placer gold production in the territory. Through cooperation with the placer mining industry, scientists have been able to study exposures containing paleoenvironmental information that extends back 3 million years.