CAPPS: AGE OF THE LAST GREAT GLACIATION 109 



in the upper portion of the White River basin in the summer 

 of 1914 some facts were obtained which throw hght on the 

 problem of the length of time which has elapsed since Russell 

 Glacier, a large, vigorous glacier in which White River heads, 

 retreated to approximately its present position. Russell Gla- 

 cier draws its ice-supply from a high, rugged range of moun- 

 tains near the international boundary. The main body of the 

 glacier lies in a pass and a portion of its drainage goes to the Cop- 

 per River basin, although the main discharge is to the Yukon, 

 It gives abundant evidence of active movement, and although 

 its lower end is well covered by morainal material, the detritus 

 has a very fresh appearance, and vegetation has secured only 

 a scanty foothold upon it. It may fairly be considered as an 

 average example of the glaciers of the Wrangell Mountains 

 and it may be inferred that the major events of its history 

 have been roughly duplicated by the other similar glaciers in 

 the same general region. 



At a point on the north side of White River about* 8 miles 

 below the source of that stream in Russell Glacier, the river 

 has eroded its bank to form a high blufT which for an east and 

 west distance of over a mile shows excellent exposures. Al- 

 though its height and the thickness of its constituent mem- 

 bers vary somewhat from place to place, a single section will 

 serve well to illustrate the conditions found there. The base 

 of the bluff at the point measured (fig. 1) shows 30 feet of typi- 

 cal, unconsolidated and unoxydized glacial till, with an un- 

 even, rolling surface. Above the till and extending to the top 

 of the bluff is 39 feet of fibrous, peaty vegetable material, full of 

 stumps and roots, but probably formed for the most part of 

 the remains of sphagnum moss (figs. 2 and 3). Seven feet 

 below the top of the bluff the peat is interrupted by a two- 

 foot layer of white volcanic ash. The surface of the ground 

 above the bluff is covered by a thick coating of sphagnum moss 

 and supports also a dense forest of spruce, with scanty under- 

 brush. The peat, ash and glacial till are permanently frozen a 

 few inches back from the face of the bluff, even though having 

 a south exposure, and subjected to the long hours of summer 



