Rork II in, Loiiij l.sldiKl, X. Y .— Briisnn. 229- 
have unloaded all their burden along the line of the ter- 
minal moraine, as no erratics of any size are found on the 
southern plain. Some of the advocates of floating ice have 
suggested that bergs would naturally become stranded on the 
higher elevations ; and the absence of boulders between the 
two moraines seems to give weight to this suggestion, but as 
all the erratics have come from the north, why is it that the 
bergs which carried them did not become stranded on the- 
northern moraine, the more elevated of the two? It is true 
that the boulders are more abundant on the north side of the 
island, but that some of them escaped gives us reason to sup- 
pose that a few woiild have been carried beyond the southern 
ridge, if floating ice was the means of transportation. That 
none were deposited in the valley between remains a mystery,, 
no matter what theory we adopt; but the phenomenon is not 
peculiar to Long Island alone, as it has been noted in other 
glacial regions. 
On the west end of the island, boulders, as a general thing, 
lie scattered in the valleys as well as on the ridges. It is only 
when we enter the Peconic depression, about opposite Port 
Jefferson, that the absence of boulders becomes conspicuous. 
This fact has led some glacialists to believe that the two 
ridges, separated by the Peconic valley, represent tw^o distinct 
ice-sheets, but the present writer, after several years of care- 
ful study, can see no evidence of more than one. The con- 
nection of old river channels, with their effect on the whole 
contour of the island, precludes the dual theory ; for that the 
streams flowing under the ice-sheet and advancing with it 
from the mainland had a great influence, not only in forming 
the valleys, but in giving shape to the hills, there can be no 
question, as I have tried to show in my paper on "The Ups 
and Downs of Long Island."* 
The fact has been noted that opposite to the bay depres- 
sions, on the north side of the island, the terminal moraine 
becomes more broken and the glacial detritus is washed out 
in front of it and shaped into hummocky ridges or kames. To 
the north of Rock hill, on the soiind, is the Wading river in- 
dentation, which cuts through the northern moraine, and the 
old glacial channels can be traced into the |)onds and marshes 
of the Peconic valley. 
*Am. Geologist, vol. xv, pp. 188-11)2, March, 1895. 
