re 
oe a 
oad 
OF 
PROCEEDINGS 
THE 
NATURAL SCIENCE ASSOCIATION 
OF STATEN 
ISLAND. ‘aie 
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ae 
Vov. VIII. No. 2. 
The regular meeting of the Association 
was held at the Staten Island Academy. 
In the absence of the president Mr. How- 
ard R. Bayne was elected chairman fro “em, 
Mr. Arthur G. Thompson, Rosebank, was 
elected an active member. 
Mr C. A. Ingalls was elected curator. 
The following paper by Mr. L. P. Gratacap 
was read : 
THE CLOVE VALLEY PLEISTOCENE 
LAKE BASIN. 
A paragraph quoted in our Proceedings of 
October 13th, 1g00, taken from the ‘Report 
upon New York's Water Supply," etc,, and 
referring to the geological import of the Clove 
Valley, recalls some speculations indulged in 
by the writer for many years, in regard to 
that interesting and formerly very beautiful 
depression. This valley is a topographical 
feature that strikes the geological observer at 
once and suggestsa series of surmises in re- 
gard to its origin. It is essentially a serpen- 
tine-walled depr®ssion which owes its general 
form to conditions or agencies which date as 
far back as Archean time. If the serpentine 
hills which surround it are the result of 
changed hornblende rocks (schists ?), and if 
these represent metamorphosed igneous 
rocks, the depression may have begun at the 
time when these latter first appeared. It 
certainly does not seem probable that this 
valley was at any time solidly filled up with 
serpentine or other rock masses, and that it 
has been excavated by aerial fluviatile, or 
glacial agents. The base-leveling of the sur- 
rounding serpentine hills is quite uniform and 
it is difficult to conceive of any action especi- 
ally centralized which would have sccoped 
Mot 
JANUARY r2th, rgor. 
out the contents of this bowl, if its original 
surface had been continuous with the tops of 
the encircling walls. 
Assuming then it was an original topographi- 
ical feature, not unlike, on a greatly reduced 
scale, the gaps existing between parallel and 
subsequently confluent hill or mountain rang- 
es, as in the Appalachian region, its later his- 
tory offers a field for conjecture, which may 
be partially at least, helped by observation 
upon its present aspect. 
It has its walls broken down at two points, 
which are somewhat ina line with each other, 
as if they might have been the exit and en- 
trance of tides from the ocean, or common 
points in the course of a short stream. One 
of these 6penings occurs to the sonth, at the 
Clove, where the Midland trolley line con- 
nects with its Richmond Road branch, and 
the other to the north, along the line of the 
valley in which are located Britton’s, Mart- 
ling’s and Brooks’ ponds. It is probable that 
these gateways to the valley were formed in 
preglacial time, indecd in Archzan or earlier 
Paleozoic time It seems to the writer that 
the Clove Road gap represents a breach ef- 
fected by weathering and the attacks of 
oceanic storms while the valley northward 
isa river course or a passage way for the 
drainage of the serpentine highlands at a 
time when their elevation in all probability 
exceeded their present altitude ten or more 
times, and has been worn down by aqueous 
or river erosion 
Of course glaciation, which so profoundly 
modified all surface features, affected the 
character of our valley. It changed it prin- 
cipally by leaving over ita blanket of drift, 
greatly filling up its original floor, and possi- 
