Stratigraphic, sedimentologic, geomorphic and geophysical investigations were made of a 1000 km reach of the unglaciated middle Yukon River between central Yukon and Alaska. The purpose is to examine the record of a large northern latitude river's response to climate change over the last 3 million years. Permafrost first appears in the Yukon basin, and its first known occurrence in North America, in the form of ice-wedge casts in the Klondike area at 3.2 Ma. The first Cordilleran glaciation of Yukon follows prior to 2.6 Ma showing a strong synchroneity with North Pacific ocean core records. This extensive glaciation is associated with diversion of a south-flowing paleo-Yukon River northwest into central Alaska. Near the mouth of Charley [...]
