Correxpondtnce. • 63 
ger portion of the moraine, until the valley of the Delaware is reached. 
Here the moraine topography is interrupted by, and gives place to the 
gently undulating surface of the over-wash plain, which is continued to 
Trenton and beyond." There is no river at present flowing across the 
Hempstead plains, but the old water course, referred to, would indicate 
that the same conditions prevailed here during the closing scenes of the 
glacial period as in the valley of the Delaware. 
Harbor Hill at Roslyn, 384 feet in hight, is stratified almost to its 
summit. This shows the powerful action of the glacial currents, and 
the whole fluviatile character of the plains tells the story of the deluge. 
Coarse detritus covers the highest ridges, and the finer sediment is 
washed out to the ocean, as at Far Rockaway, tilling in the southern 
bays and forming a pathway to the sea, as at this point the land projects 
out to the sea beaches that fringe our coast, and which were undoubt- 
edly originally formed by glacial currents. The whole of the south side 
of the island has beau generally looked upon as a dereliction of the sea, 
and Prof. Franklin Hooper, directc^r of ttie Brooklyn Institute, in a re- 
cent lecture on the geological formation of Long Island, stated that he 
was prepared to prove its marine origin. and began his interesting lecture 
by a beautiful view of the Long Island coast, showing how the waves 
of the sea build up the long line of sea-beaches along the Atlantic bor- 
der. Now the fact is the waves destroy more than they build up, as all 
the evidence seems to show that the sea is gaining on the land. In a 
paper on the "Ups and Downs of Long Island"* I proposed to explain 
how the south side of the island, as well as the so called sea-beaches, 
had been formed by glacial currents, and the longer these phenomena 
are studied the more I am convinced that the waves of the sea had 
little to do in the formation of the island. 
There is much, however, that still seems ine.\-plicable, and it will re- 
quire years of patient and careful study to solve the many proVjlems 
which so far have baffled the ablest scientists. 
As far as the present writer is aware, not a single marine shell has 
been found in the region of the Hemjjstead plains. A fragment of a 
crinoidal stem wasfoundin boring a well on BJlrnum's island, but this 
was undoubtedly washed in from some older paleozoic formation. Drift 
wood is nearly everywhere found in digging wells. At Westbury a log 
of wood, three feet long and one in diameter, Was found at the depth of 
103 feet. It was not very much decayed. Another was found near it, 
at not so great a depth, and on the southern border of the plain, recent 
borings for the Brooklyn water supply great quantities of wood have 
been met with at various depths. The specimens have been identified 
with forest trees that grew along our coast at the time of the glacial 
period, and there is no evidence I believe, that the wood found repre- 
sents interglacial forest beds. The position of most of the logs e.xhuraed 
would indicate that they were washed in during the deposition of the 
sand and gravel. It is a singular fact, however, that these wood frag- 
*Am. Geologist, uo. 3, vol. xv, p. 1>8. • 
