160 
GEOLOGY OF THE FIRST DISTRICT. 
Where excavations, or the wash of the waves expose the slate and overlying drift deposit, these 
abraded pebbles and boulders may occasionally be dug out.* * 
3. Montauk point is a good example, and all the south shore for some distance west; the drift deposit 
is well exposed in high banks, and is covered in some places by the quaternary sands, clays and 
loams. (Vide PI. 4, fig. 2.)t 
Composition of the Drift Deposits. 
The drift deposits are composed of fragments of all the preexisting rocks, exposed to the 
action of the causes that have contributed to their transportation and deposition. They are 
mostly coarse, composed of blocks, boulders, pebbles, gravel and sand, sometimes loose, but 
frequently partially aggregated by argillaceous matter, that renders a pick necessary to dig it. 
Most of the material that is called “ hardpan”^ in New-England and New-York, and “ marl ” 
on some parts of Long island, is formed of blocks, boulders, pebbles, gravel, sand and clay, 
partially cemented by the latter. The gravel beds are also cemented by carbonate of lime 
into a coarse sandstone and conglomerate, by the action of alluvial causes. This may be ob¬ 
served at West-Point, and between Washington’s valley and the base of the Crow’s Nest, on 
the west shore of the Hudson.§ 
Topographical Features. 
The topographical features of this formation are somewhat peculiar. In the eastern and 
southern parts of New-York, and in Massachusetts, Rhode-Island and Connecticut, the drift, 
where it is well exposed to view, is very hilly and irregular, and is composed of round-backed 
hillocks with bowl-shaped cavities or valleys between them. These little hills are entirely 
(T, Sand and gravel beds. 
T’, Grey clay. 
* Vide Plate 27, fig. 4.<; T”, Blue clay. 
I T’”, Drift of boulders, pebbles, gravel and clay. 
V,H, Slate rocks of Hudson slate group. 
t This figure is corrected as it should be under the quaternary deposits in this volume, page 126. 
t The term “ hardpan” is also applied to what Prof. Eaton has called analluvium, or rock crumbled and disintegrated in place. 
They are easily distinguished. 
^ Geological Report of New-York, 1833. Final Report, 1842, p. 123. Mather on Diluvion; printed for the Cadets of the 
United States Military Academy, 1835, p. 7. 
Prof. Hitchcock has also described consolidated gravel, three miles from Williams College in Pownal, Vt. I have also seen 
the locality. A deposit of similar characters occurs at Zanesville, Ohio ; also at the Narrows in the valley of the Scioto, two 
miles from Chillicothe. Dr. Houghton and others describe it also in Michigan. It is not uncommon in the United States, but 
the above are the principal localities that have been described, and all of which, except those in Michigan, I have examined. 
Dr. Buckland has mentioned consolidated gravel in Europe, near the Monastery of Kremminster in Upper Austria, where it is 
quarried for building, and contains the bones of the Ursus spelseus (Rel. Diluvian®, p. 101); also in gravel pits near Oxford, 
England (Reliqu® Diluvian®, pp. 71, 160). Prof. Briggs describes consolidated gravel, and pudding-stone cemented by carbonate 
of lime, in the gravel beds near Troy, N. Y. (Field Notes of Geol. Survey, 1st Dist. Vol. 2,ip. 8 ) 
