GLACIATION OF WRANGELL MOUNTAINS 53 



Aside from the fan-building streams from the south, the valleys of 

 North Fork, Lime Creek, Middle Fork, and Wiley Creek all have 

 gravel bars extending upstream for some distance above their junctions 

 with the White River gravels. 



Terraces. — ^In this valley remnants of high terraces were noted only 

 on the north side of the river. For about two miles below the mouth 

 of the Lime Creek Canyon, there is a bench of coarse gravels -from 30 

 to 50 feet high. Farther east, along the south base of the Ping Pong 

 Mountain ridge, the river bluff shows a 50-foot cut. Of this section 

 (Fig. 12), the lower 35 feet are composed of coarse, rudely stratified 



Fig. II. — A north-south section across the White River Valley, about S§ miles 

 west of the international boundary, a, White River; h, alluvial fan; c, small glacier; 

 d, peak two miles west of Mount Natazhat. 



gravels. Above this are 15 feet of blue glacial till. Locally the 

 gravel beds immediately below the till are much distorted and crum- 

 pled, showing that after the gravels were deposited, the glacier 

 advanced over them, disturbing their bedding and depositing a sheet 

 of till. There may be gravels of the same age south of the White 

 River, but the present tributaries from the mountains to the south are 

 so actively engaged in building alluvial fans that any remnants of 

 higher terrace gravels which might have existed on that side of the 

 river have been cut away, or covered up by more recent deposits. 



Extent of earlier glacier. — ^At the time of the great ice-advance, a 

 glacier, of which Russell Glacier is the surviving remnant, moved 

 eastward along the 'White Valley and extended well across the inter- 

 national boundary. At the boundary it had a width of more than 10 

 miles, and its surface stood more than 1,600 feet above the present 

 level of the White River at this place, for there are evidences of glacia- 



