ON THE GEOLOGY OF THE ISLAND OF AQUIDNECK. 615 
to their speedy destruction. We thus see that by far the larger 
part of the eroded materials of the ancient continental glaciers 
must have been rapidly converted into mud which would have been 
easily swept away by the sub-glacial streams, which would have 
coursed beneath the great ice sheets of this region, just as they 
now flow beneath the Greenland glaciers and bear their tide of 
muddy water to the sea. 
here are only two points where the glacial deposits seem 
capable of any other interpretation. Two-thirds of a mile north 
of the coal mines on the west side of the railway, there is a mass 
of drift having a form which strongly suggests that it might have 
‘been deposited as a terminal moraine. It is in the form of a 
ridge a few hundred feet long, and by its position, shape and struc- 
ture is likely to have been the mass accumulated during the retreat 
of the ice stream when it paused for awhile with its termination 
at that point. The other point is at Portsmouth Grove, a few hun- 
dred feet to the south and east of the railroad station, where the 
drift is piled in a number of conical hills which lie in a general 
north and south direction. The internal structure is not shown 
by sections as at the other point, but there can be no reasonable 
doubt that the whole mass is of drift material. It is pretty clear 
that these hills have been formed in a different-way from, the rest 
of the drift ; there seems no other reasonable explanation than to 
not readily determined ; there is some interesting evidence, how- 
ever, to be gained from a study of certain instances of wear found 
