ger 
730 FRANK CARNEY 
aspect of the region of our cross section, however, is very important. 
In the uplands, or divide plateau areas, glaciated surfaces are found 
wherever the rock is not drift-covered. These striated surfaces attest 
considerable planing or abrasive work by the ice-sheet. As these flat 
elevated areas decline to the valleys we find a range of very subdued 
ice-work, the zone of disturbed subjacent strata, and of residual rock 
decay in situ. But proceeding down the valley slopes the evidence 
of ice-corrasion gradually increases. The strongest evidence so far 
noted in the field is found within a short distance vertically of the flood 
plain. We have then (Fig. 5) three ranges showing variation in the 
effectiveness of ice-erosion: (1) the range of mild erosion; (2) of 
inefficient erosion; and (3) of vigorous erosion. 
