|
222
|
GEOLOGY OF NEW YORK CITY
|
||
|
|
|||
|
bridges.
It was substantially vegetable residues, generally homogeneous, and
inclosing in spots flattened twigs and small branches, while, in its
upper layers roots, tendrils, and innumerable fibers appeared. It
formed a brown body, deeply carbonized in black streaks, and drying to
a board-like, leathery fabric, hard, feebly elastic, and tenacious.
The accompanying diagram shows its distribution and thickness
(furnished by the Degnon Construction Co.). It reached a depth of over
forty feet in some sections, rested on clay, was covered by filling,
and occupied saucers and pockets which may have been previously
water-excavated gullies and basins. Mr. H. Cleary (assistant engineer)
described the conditions as follows:
"
The peat varies in depth (from 4 inches to 25 feet), and in composition
depending upon its location in the pond. That in the Leonard Street
area is deep (25 feet maximum), dense, brownish-black, fibrillous, and
nearly homogeneous in texture, having a very slight odor, and appears
to have been displaced by the gravel filling deposited upon it. That in
the peripheral area at northerly and southerly limits of pond is
shallower, fairly uniform (3 feet to 4 feet) in depth, and nearly
level, is tan colored, odorless, dense, and fibrillous with horizontal
lamination, containing roots, twigs, branches, leaves, and logs in a
partial state of decomposition, but very compactly embedded in the
peat. At northern area of pond many cedar stumps and roots in situ were
found in a very slightly decomposed state, but compactly imbedded in
the peat. The peat rested directly upon blue clay, into which the
rootlets had freely penetrated and were visible passing into the sand
below the clay in a flattened and decomposed state. The clay varies
under the central and southerly areas of the pond from several feet to
a few inches in depth, being uniformly about two feet thick under
northerly pond area of tan colored peat.
" This pond was filled in during the years 1800 to 1834 to the level of the street surface. Mean water level stands at
|
|||
|
|
|||