Maps And Descriptions of Routes of Exploration in Alaska in 1898 With General I
Maps And Descriptions of Routes of Exploration in Alaska in 1898 With General I
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THE YUKON DISTRICT, 91 GLACIATION. The northern limit of giaciation, as determined by the investiga- tions of Dawson, Eussell, and Hayes, crosses the Pelly near the mouth of the McMillan River, the Lewes near the Big Sabnon River, and the White near the month of the Doujek River. The Tanana River as far as explored by me was found to be beyond the line of general glaciation. North of this limit local glaciation has occurred on some of the higher mountains. After the retreat of the ice the regio...n stood at a much lower level, and the silts and gravels were deposited probably in part in fresh-water lakes and in part as littoral marine sediments in estuaries. ' The subsequent elevation and dissection of these deposits produced the terraces and bluffs which are such strik- ing features of the topography along most of the rivere. RECENT VOLCANIC ACTIVITY. Doctors Dawson and Hayes have described the white volcanic ash which forms the surface bed over large areas in the region of the White River, the lower courses of the Pelly and Lewes, and the Upper Tanana.
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