170 /. HARLEN BRETZ 



stream valleys, appears identical with that shown in the vicinity of 

 Seattle, on the slope of the Bald Hills, and in other widely separated 

 regions. The matrix is somewhat sandy, the pebbles and bowlders 

 are rounded, and large erratics are rare. Granite of various kinds 

 is abundant, though granite is not known in the neighboring 

 Olympics. The till is seen to overlie fresh gravel in a few sections 

 with a thickness of about three feet. Its altitude probably does 

 not reach much above 450 feet A.T. 



Lake Nahwatzel lies in a decidedly morainic area, the monoto- 

 nous gravel plain giving place to rolling hills of till which rise 50 

 feet above the lake surface. These morainic hills lie probably 

 over the lowest preglacial rock surface between the Black Hills 

 uplift and the Olympic foothills, and in such a situation we may 

 find an explanation of the more pronounced morainic expression. 



The till along the margin from Matlock to the Black Hills 

 often shows a large proportion of deep red clayey material inter- 

 mingled with fresh pebbles. The presence of such material, 

 doubtless from the incorporation of the residual soil of basalt of 

 which there are frequent outcrops, is to be expected near the ice 

 margin providing the ice was overriding a region previously 

 unglaciated. 



The approximate moraine course from Matlock northward 

 bends abruptly back toward Hood's Canal, the greater length of 

 which is closely bordered by the Olympic Mountains on the west. 

 The extent to which Puget Sound drift penetrated into the valleys 

 of these mountains is known in but one case, that of the Skokomish 

 River. Rock along this stream's course is practically absent below 

 Lake Cushman, while the mountain walls rise almost from the lake 

 shores on the upstream side. 



Puget Sound drift of Vashon age composes an extensive plateau 

 400-800 feet above Hood's Canal, extending back from Lilliwaup 

 Creek directly west to Lake Cushman and also southward to the 

 broad, pre- Vashon lower Skokomish valley. One large rock hill 

 rises through this till plateau just south of the Lilliwaup, otherwise 

 the surface is of rolling ground moraine with occasional shallow 

 kettles. Across the Skokomish to the west are foothills with little 

 or no drift. To the south of the great bend of this stream, extensive 



