1887. | NEW YORK ACADEMY OF SCIENCES, 53 
ble matter, sands, clays in alternate strata, 50 feet; sand 
and gravel, 10 feet; total, 70 feet. 
College place. Diluvium, 20 feet; stratified sand and gravel, 60 
feet; total, 80 feet. 
Fulton Market. Made ground, 15 feet; strat. sands, blue clay, 
and river mud, 115 feet; total, 130 feet. 
‘¢ Hall’s Hotel,” north of last. The same, ending with a bed of 
gravel, 126 feet to rock. 
City Hall. 90 feet to rock. 
New Church St. 86 feet through quicksand. 
Herald Building. 40 feet (rock?). 
Western Union Building. 24 feet (rock?). 
Centre and Reade Sts. Coarse gravel, 30 feet; rock not reached. 
Tombs. Made ground, 40 feet; black mud, 30 feet; blue clay, 
5 to 10 feet; gravel to rock, over 75-80 feet. 
Grand and Wooster Sts. Made ground, 40 feet; mud, clay, sand, 
and vegetable matter, 20 feet; blue clay, 6 feet; coarse sand 
and gravel, 6 feet; to rock, 72 feet. 
Bleecker St. and B’way. Strat. sand and gravel, 42 feet; rock. 
Perry and W. 11th St. Sand, 40 feet; red clay, 23 feet; to rock, 
63 feet. 
35 Union Square. 23 feet to rock. 
415 E. 54th St. 10 feet sand to rock. 
99th St. and Second Ave. Made ground, 8 feet; dock mud, 18 
feet; sand, 12 feet; total, 38 feet; rock? 
The great depth of made ground (40 ft.) at the Tombs, is due 
to the former existence on its site of a pond or quagmire, known 
as the Collect, in the bottom of which was found a peat, which, 
strangely enough, was impregnated with salt." This would in- 
dicate that it was formerly open to the rush of the tides, as the 
saline marshes are formed elsewhere. ‘The peat had butternuts 
and acorns mixed through it. he drift hills of this lower part 
of the island attained, in one or two instances, a height of 100 
feet above the street, but in general were 25 to 50 feet. ‘They 
did not differ from the strata beneath them, except in the 
absence of river mud. The question thus naturally arises, 
whether or not the entire drift area, or indeed all the island 
but the gneiss hillocks, was once covered as high as this, and sub- 
sequently cleared by erosion. ‘The deposit of the glacier and its 
flood may have been thicker yet, but, at all events, it is certain 
that the island must have been 100 feet lower, to bring the high- 
est drift summit under water. And, further, the subterranean 
strata are 75 feet thick under this hill,? largely made up of sand 
1 Cozzens, p. 27. 
2 The hill was on the corner of Grand and Orange streets, not far from 
the section at Grand-and’Wooster, on which the conclusions are based. 
