DAVIS : GLACIAL EROSION. 
305 
narrow inlets of non-glaciated lands are simply submerged land- 
valleys ; the intricate coast-lines of such regions have been deter¬ 
mined by preceding subaerial denudation.” Again : “ In a word, 
fiords are merely the drowned valleys of severely glaciated moun¬ 
tain-tracts.” (' 98 , 263, 250.) The deep waters in the valley of the 
Hudson through the Highlands of southeastern New York are the 
most fiord-like in the eastern United States, and they are universally 
explained as the result of submergence of a normal river valley; but 
the constricted ice current that must have flowed through the High¬ 
land gorge may have been energetic enough to deepen its bed 
beneath sea-level, and since the ice melted away, who can say how 
much submergence beneath preglacial levels has taken place. I do 
not know how far this view of the matter has been taken by ear¬ 
lier advocates of strong glacial erosion, but for my own part, the 
acceptance of such a possibility means a complete reversal of the 
belief that I held two years ago. The reversal is, however, accom¬ 
panied by the memory that it was always difficult to understand 
why submergence and glaciation were so closely associated : even if 
glaciation had caused depression, it was difficult to understand why 
the relief from ice pressure in postglacial time had not now been 
followed by a rise of the land much nearer to its former altitude 
than would be the case if the greater part of the depth of fiords is 
explained by submergence. 
The Origin of Corrie JBasins. — On pursuing the above line of 
consideration a little further, it may give some light on the occur¬ 
rence of the small rock basins that are so often found in the floor of 
cliff-walled corries. Imagine that a large glacial system has become 
maturely established, and that it “ rises ” in many blunt head- 
branches that have excavated corries in a preglacial mountain mass, 
and have cut down channels, at their junction with the larger 
branches or trunk glacier, to a depth appropriate to their volume. 
Unless the erosion of the corries has been guided by differences of 
rock structure, there does not seem to be reason for their possessing 
a basined floor at this stage of development; but if a change of 
climate should now cause the trunk glacier to disappear, while many 
of the blunt head-branches remain in their corries, each little glacier 
thus isolated will repeat the conditions of erosion above inferred for 
the trunk glacier; and if this style of glaciation linger long enough, 
rock basins may very generally characterize the floors of the corries 
when the ice finally melts away. Figure 7 may make this clearer. 
Let the broken line, ABC, be the slope of a preglacial lateral ravine 
