334 J HARLEN BRETZ 



out as a broad spatula over the low-lying northwest salient of the 

 Olympic Peninsula south of the strait. It reached westward nearly 

 or quite to longitude 125° W., 10 or 12 miles off the Washington 

 coast beyond Cape Flattery. 



There is a narrow foreland between the Olympic Mountains and 

 Juan de Fuca Strait, composed largely of Pleistocene materials. 

 It is separated from the coastal plain west of the mountains by a 

 group of ridges which strike parallel to the shore of the strait. 

 They extend from Crescent Lake to the extremity of the Olympic 

 Peninsula. They are everywhere several hundred feet high and 

 certain summits are mapped as high as 4,000 feet. They serve as 

 a divide between Soleduck River on the south and the short streams 

 tributary to the Strait on the north. 



The foreland terrace north of these ridges gradually narrows 

 westward until it disappears, while the valley on the south side, 

 between the ridges and the main mass of the Olympics, broadens 

 and joins the coastal plain facing the Pacific. 



The slopes of these ridges bear little or no glacial drift but the 

 valleys between them contain deposits of Vashon till. The till 

 of the foreland and in these valleys is, in general, light in color and 

 contains plentiful granitic material, very much like the Vashon till 

 of Puget Sound. Many erratics are of identical material. It 

 seems clear that the debris was brought from the same feeding 

 grounds north of the international boundary Hne. 



But west of Crescent Lake and south of these ridges, the drift 

 contains a large amount of basalt and dark-colored sandstone and 

 conglomeratic debris which came from the Olympics immediately to 

 the south, and which is not found in the till north of the ridges. 



The eastern portion of these ridges apparently served as an 

 imperfect barrier in the Juan de Fuca Glacier between drift from 

 the distant Georgia Strait and from the nearby Olympics. Farther 

 west, however, the ridges were overridden by the northern ice which 

 carried its granitic drift southward almost to the mouth of Quil- 

 layute River. 



The coastal plain of the Olympic Peninsula is densely forested. 

 There are few roads and clearings. Such as do exist are along the 

 streams. These conditions have forbidden any attempt to trace a 



