206 
The American Geologist. 
October. 1898 
Little Bend 
Columbia. 
CO^TouR iNTCRML IS asrr. «CEPT 
On TERRACt 8, MOUNTAIM WHfR£50'r 
Diagram No. 1. 
Any more detailed description of the topographic features 
would anticipate points that I shall hope to bring out in con- 
sidering the phenomena in connection with the glacial period. 
The evidence of ice action in Okanogan county is most pro- 
nounced. Indeed, one has only to note the fresh appearance 
of terminal moraines, kettle-holes and terraces, together with 
the occurrence of glaciers by the score on the western ranges, 
to be convinced that the ice age has retreated none too soon. 
Although the glaciation of this region was not effected by a 
general ice-sheet, it is because the work was accomplished by 
a local and somewhat restricted action, that the results pre- 
sent certain unique features. We should expect that in the 
several phases of advance and retreat the glaciers would be 
largely obedient to the conditions imposed by the previous 
valleys of erosion. And furthermore, although we should 
concede a general condition of moisture and precipitation 
throughout the region, the varying hights of the mountains 
and the dififering widths of the valleys would principally de- 
termine the lower limits of the advancing glaciers. Hence 
we are to look for no regular ice-sheet margin, but to remem- 
ber that each individual glacier will halt or deploy upon the 
plain in a manner depending on the size of its area of accumu- 
lation, its distance, and gradient from the divide. 
