182 



THE ICE AGE IN NORTH AMERICA. 



by a series of ridges showing every mark of glacial origin. 

 Not only is the surface of these ridges covered with bowl- 

 ders, but wherever the streets have cut down into the soil 

 they show, at the depth of a few feet, an unstratified deposit 

 abounding in striated stones. Superimposed upon this ridge 

 there is a thin stratitied deposit of varying depth, but in- 

 creasing in extent down the slope toward tide-water. 



At Fort Townsend, on the Strait of Juan de Fuca, and 

 forty miles northwest of Seattle, the coarsely stratified de- 

 posit is much greater in extent. A noteworthy section of 

 this I had the privilege of studying at Foint Wilson, two 

 miles and a half northwest of Fort Townsend. Here, facing 



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Fig. 60.— Section of the deposit at Point Wilson described in the text, showing one hun- 

 dred and fifty feet in height, about one hundred of which is coarsely stratified, and 

 contains layers of vegetable matter. Bowlders from till at the top have fallen down 

 to form a talus at the water's edge. 



the strait toward the north, is a perpendicular bluff from one 

 hundred and fifty to two hundred feet in height, composed 



