TERMINAL MORAINE OF PUGET SOUND GLACIER 165 



distinct kames. The till is the characteristic blue-gray arenaceous 

 material, with laminae and rounded cobbles, which is identified 

 throughout the Puget Sound country as Vashon. The presence of 

 numerous varieties of rolled granite cobbles in the moraine and in 

 the plain southward is a safe criterion for the identification of the 

 till as the Vashon rather than the Osceola till of the Cascades. 

 The moraine ridges on its northern flank and broad till plain lying 

 southward are topographic features in accord with this interpreta- 

 tion. Though the boundary between Vashon and Osceola till 

 was not located, it obviously lies between the Mt. Rainier high- 

 way and Lake Kapowsin, the lake lying at the base of the foothills 

 of Mt. Rainier. 



The dominance of Puget Sound ice at the western base of the 

 Rainier foothill country is proved conclusively by the common 

 occurrence of bowlders and cobbles of several granitic types char- 

 acteristic of the drift of Puget Sound and unknown to the adjacent 

 Cascades. 



The postglacial gorge of Nisqually River, 300 feet in maximum 

 depth and with vertical and even overhanging walls, is two miles 

 long and occurs where the river enters the area of Puget Sound 

 drift. A 40-foot section of outwash, containing frequent Vashon 

 drift materials, overlies the rock floor in which the canyon is cut 

 at LeGrande. Farther up the canyon no drift was found. 



A trail crosses the divide between the Nisqually and Des Chutes 

 rivers just south of the canyon noted, entering the latter stream 

 at the headwaters. Scattered granitic bowlders of Vashon drift 

 were found up to an altitude of 1,220 feet on the Nisqually side, 

 but no traces of drift were found in the remaining 200 feet of 

 ascent or in the valley of the Des Chutes on the other side until 

 the altitude of 1,200 feet was reached, a few miles down from the 

 headwaters. Here scattered erratics occur on the hillsides, and at 

 900 feet is a level terrace composed of fine material with inter- 

 spersed pebbles, probably a lacustrine deposit caused by the ice 

 entering the lower valley and blocking the drainage. 



Two miles below this terrace, whose soil has determined the loca- 

 tion of several small farms in the wilderness, is found the terminal 

 moraine of the Puget Sound Vashon glacier. The surface is exceed- 



