88 W. Upham—Terminal Moraines 
ice-sheet was even more conspicuously than its unmodified 
terminal accumulations of till. The latter appear with scarcely 
any modified drift in this moraine from Fort Hamilton to Ros- 
lyn; but thence to Amagansett a remarkable contrast is pre: 
sented, the moraine of till being nearly everywhere buried by 
that of fluvial gravel and sand. Bowlders in these stratified 
deposits appear to have been brought by ice-floes or small bergs, 
borne on the glacial floods. Their abundance on Montauk 
may indicate a slight advance of the glacial sheet during or 
after the deposition of the stratified beds, carrying forward a 
multitude of bowlders which remained on the surface of the 
ice because they could not be removed by its streams. At its 
a retreat these would be dropped, forming a deposit of upper 
ti $ 
ill. 
Previous to the deposition of the series of hills of modified 
drift which we have described, it appears that the ice-sheet 
reached five miles south of this line, though perhaps only for 
a short time. This is shown by Manetto and Pine Hills, which 
extend in massive north-to-south ridges from the West Hills 
by Melville to Farmingdale. They are composed of stratified 
gravel and sand with rare bowlders, and have a height which 
declines from 300 feet above sea at the north to 150 at the 
south. Three miles farther east, and separated from the fore- 
going by a plain about 100 feet above sea, are the Halfway 
Hollow Hills, of similar character and nearly equal height, 
extending some three miles south from the west part of the 
Comac Hills. Opposite to these, on the north side of the west- 
to-east moraine series, are two spurs of the Dix Hills, which 
reach three or four miles north from this series, being likewise 
have been deposited like kames, in ice-walled river-channels 
ormed upon the surface of the glacial sheet when it was rap- 
idly melting. The southern ridges are thus of earlier date than 
the principal series of terminal deposits, while those on the 
north were probably formed immediately after this series dur- 
ing the retreat of the ice-margin. 
e part of Long Island south of this terminal moraine con- 
sists of nearly level plains of fine gravel and sand, five to ten 
miles in width and extending a hundred miles in length. The 
height of their north portion at the foot of the hills varies from 
