180 GEORGE B. RIGG 



the barren portion of the elevations is everywhere characterized by 

 the gravelly black soil, and the forested portion by the yellow 

 clay soil. The substratum conditions are not the same in all 

 four — Cattle Point and South Hill being moraines and Spieden 

 Island and Sentinel Island being bed rock. 



It was found that in one place on the Cattle Point elevation a 

 portion of the northern slope is barren of trees, and this portion 

 was found to be characterized by the black gravelly soil, just as 

 the barren southern slopes are. The low ridge at Cattle Point 

 above referred to was found to have gravelly soil on both slopes. 



Fig. 3 A portion of the summit of Cattle Point Hill, showing distorted and 

 dead trees at the edge of the forest (photograph by Dr. T. C. Frye). 



It was found also that on South Hill, Spieden Island, and Sen- 

 tinel Island the trees at the summit show practically no distorting 

 effect of wind. Whatever wind effect takes place is confined to 

 the very tops of the trees and is so slight that it is not noticeable 

 in any general view of these elevations, being detected only by 

 a careful scrutinizing of individual trees. The bending of the 

 tops of trees, apparently as a result of wind, is common through- 

 out San Juan Island, and the bending of the tops of occasional 



