Correspondence. 189 
through tlip fronial phiiii to tlie bays, where a mrcting of tlie waters 
again took place and resulted in the formation of the bays themselves. 
At least they gave tiiem their fonlour. and tin' inlervenjng islands, as 
already intimated, are the same in origin as tiir liillocivs in the old 
abandoned river channels and depressions to the noriii. 
Jamaica, (Jre.it South and other bay depressions on liic soiilli siile of 
the island, show the effect of glacial streams upon them, and in places, 
where the flow of water was great, the detritus has Hlli'd in these bay 
depre.ssions altogether, or nearly so, as at Far Roekaway. wiu're a nar- 
row strip of land divides .Jamaiea and the Great South bays, for here 
the floods broke through with great force from Flushing bay jn the 
north. The points along the Great South bay are more or less conspic- 
uous, according to the size and force of the old glacial currents. At 
Brookhaven. where there is still (piite a stream running througii tin' 
terminal moraine from the north side of the island, it will be found, 
that a point of hind nearly separates the Great South from what is 
known as the East bay. \\ West Hampton, again, the bay only exists 
as a marshy depression, and the other Hamptons, to tlir east, conif 
down to the ocean with scarcely a bay between: the same conditions 
prevail, however, throughout the whole extent of the island. Although 
beyond Amagaiisett the south side, with its bay depressions, lias been 
swallowed up by the sea, yet, as if to complete and confirm this won- 
derful history of these glacial floods, a long arm of the terminal moraine 
is stretched out separating Amagansett and Xa]>eague. making the 
Montauk division almost an island in itself, as the low marshy dejires- 
sion leading from (iardiner"s bay to the ocean represiMils one of the old 
glacial ri\er channels. 
These f)oints, along the southern bays, were formed very much the 
same way asthe necksalong the bay indentations on the north side of the 
island. Of course, the latter has a mantle of till, which the former has 
not, except in a slight degree, for the glacier is su|)posed to have ended 
with the southern ridge. There is evidence, however, that the surface 
part of the ice-sheet e.vtended for .some distance beyond the .so-called 
terminal moraine. Some of the lower stratified deposits of clays, sands 
and gravels, on both sides of the island, may be preglacial. but it is evi- 
dent that the turbulent streams of the gri'at lee atii- are in tlif main n- 
sponsible for the upx and down.s here treated of. 
The bays, on the south, represent the last of thr downs as far as Ihry 
can be traced. The last iqi is the line of beaches along the Atlantic bor- 
der. Those beaches have always been considered marine in origin, and no 
doubt they have been greatl}' modified by wind and wave in postglacial 
times; yet, I am very confident that their original formation w.-is due to 
glacial currents, the same that swe|)t the north side of the island and 
formed the kame ridges and deltas. It is hardly reasonable to supposi- 
that such powerful currents terminated In the southern bays. and. in 
fact, there is good evidence that another doir/i existed south of the pres- 
ent shore line, although the ocean bottom in front of Long Island is said 
