PROCEHEDINGS 
OF THE 
NATURAL SCIENCE ASSOCIATION 
OF 
Vout. VII. No. 4. 
The regular meeting of the Association 
was held at the residence of Mr. Thomas 
Craig, New Brighton, with the President 
in the chair. 
Mr. A. A. Yates, Mariners’ Harbor, was 
elected an active member. 
The committee on public lectures an- 
nounced that the next one would be by 
Prof. William Hallock, of Columbia 
University, on ‘‘The Interior Heat of the 
Earth.’’ 
Dr. Arthur Hollick read the following 
communication : 
AN EXAMPLE OF ISOSTASY. 
On the west side of the Rapid Transit 
Railroad, at the Fort Wadsworth station, 
is an amphitheater-like depression in the 
moraine, part of which is occupied by the 
small body of water known as Lily or 
Liiling’s pond and part by aswamp. The 
general level of this depression is about 
75 feet above tide level. A short time ago 
Mr. Eric T. King called my attention to 
an interesting instance of ground sinking 
at the locality, due to filling in for a new 
roadbed for Tompkins avenue, which 
there crosses the swamp between the 
Fingerboard road and the railroad tracks. 
On a recent visit I found not only that 
the new roadbed had sunk, but that tbe 
ground on each side had risen and large 
red maple trees had been thrown out of 
their original vertical positions so that 
they are now inclined at various angles, 
some with their roots more or less ex- 
posed. The soil was found to consist of a 
fair quality of peat, which, after drying, 
was found to ignite readily and to main- 
tain asteady smouldering fire. Mr. King 
_ informed me that the peit has been used 
STA TEN 
ISLAND. 
Fepruary rith, 1899. 
to some extent for fuel and a fire which 
was kindled to burn off some brushwood 
started a ground fire which burned for 
several months. 
Wishing to obtaiv exact data if possible, 
as to the depth of the peat, character of 
the underlying deposits, etc., I wrote to 
Mr. Henry P. Morrison, Deputy Com- 
missioner of the Department of Highways, 
who kindly furnished me with the follow- 
ing information : 
My DrAR Dr. HOLLicK—In reply to 
your inquiries concerning the sinking of 
the roadbed of Tompkins avenue, near 
Fort Wadsworth, permit me to say that 
the location you refer to is that part of 
Tompkins avenue, about 550 feet, lying 
between the Fingerboard road and the 
S. I. R. T. R. R. tracks at Fort Wads- 
worth station. 
The fill is being made over an old earth 
road, which supported the traffic that 
went over it, but quaked and shook if 
stamped on hard. 
Some of the people living in the neigh- 
borhood state that the road was built on 
the site of an old cranberry swamp. 
While constructing the improved high- 
way, the fill, having reached a height of 
from 3 to 4 feet, began to sink and large 
and deep cracks began to appear. After 
dumping more material the fill began to 
settle more rapidly and very unevenly. 
A section would sink from 2 to 4 feet dur- 
ing a night, while an adjoining section 
would not sink at all. In one case a sec- 
ton 16 ft. x 30 ft. sank 12 ft. in 36 hours 
and continued to sink when more earth 
was dumped there. 
The old roadbed was practically level 
