1 64 /. HARLEN BRETZ 



and its incompleteness must largely be charged to the same reason. 

 Large tracts about Puget Sound are yet covered with virgin forest 

 whose density is such that passage for any considerable distance 

 is next to impossible. The lack of roads, trails, and inhabitants 

 over many square miles forces the investigator to shoulder his 

 pack of blankets and food, and travel the country on foot. De- 

 tailed work is not practicable under these circumstances. It will 

 probably be years before the moraine can be mapped with accuracy, 

 since the task must wait on the agricultural development of the 

 country. 



On the eastern margin of the Tacoma quadrangle, Willis and 

 Smith 1 found a broad sheet of till spread by a piedmont glacier 

 from the Cascades. The contact between this drift sheet, named 

 the Osceola till, and the Vashon or youngest till sheet of the Puget 

 Sound glacier was found to be marked by a belt of hummocky 

 topography of morainic aspect, considerably different from that 

 of the ground moraine on either side. No definite marginal or 

 interlobate moraines were found, the phenomena being apparently 

 referable to subglacial accumulation. Short eskers were a notable 

 feature. 



This study has taken up the continuation of the contact between 

 local glacial deposits, and those far traveled down the Puget 

 Sound depression from the north, on the south edge of the Tacoma 

 quadrangle in a densely wooded country traversed by a few second- 

 ary roads and one highway, the Mt. Rainier automobile road. The 

 geological map of the Tacoma folio maps the Rainier Pleistocene 

 drift on the south edge of the quadrangle, farther west than the 

 writer has found it. The automobile road follows a north to south 

 course for 5 or 6 miles, parallel to and about 6 miles west of Lake 

 Kapowsin, and for this whole distance traverses the till plain of the 

 Puget Sound Vashon glacier. Northward toward Tacoma are 

 extensive areas of outwash gravel deposited during the recession 

 of the Puget Sound ice. The till plain rises southward from the 

 outwash with an abrupt morainic slope, ascending 200 feet in one 

 mile. The slope is thrown into several successive ridges of till 

 trending east to west, on the south sides of some of which were 



1 Bailey Willis and G: O. Smith, op. cit. 



