6 Postelsia 
other islands also, is essentially a mass of tilted 
eneissic rocks with here and there certain terti- 
ary areas. It was subjected to heavy glaciations. 
The main course of the glaciers seems to have 
been northward through the Straits of Georgia, 
and westward, as shown by scourings on the 
rocks around Victoria, through the Straits of 
Fuca. The effect has been to leave in many 
places extensive gravel moraines and in others 
beds of boulder clay. On top of the sharply 
tilted slate rocks of the region of the Minnesota 
Seaside Station in certain places are such mo- 
rainic remains, while in others again the rocks 
jut out bare, or have only such covering as 
countless generations of decaying trees and other 
vegetation have left behind. Along the shore, 
on the projecting points mostly, there is super- 
imposed upon the slate rocks a late sandstone 
formation, while in the inlets there is usually a 
coarse grained beach deposit, formed from 
coarse sands and particles of the disintegrating 
slate. The west coast, being subjected in many 
places to unusually heavy wave action, is under- 
going comparatively rapid changes. The geo- 
