QUATERNARY DIVISION. 
123 
State Museum at Albany, and others that were filled with sand, decomposing pebbles, etc. 
The geodes and the conglomerate formed as above stated, were confined to a stratum not more 
than one foot thick, and about thirty or forty feet above the tide-water level. Boulders and 
pebbles of this same ferruginous conglomerate are found abundantly in the more recent drift 
of Long island and New-Jersey. 
At West-Point, the gravel beds of the drift deposits are aggregated into a solid conglome¬ 
rate, by the deposition of carbonate of lime. This substance invests every pebble and gravel 
stone with a white or yellowish incrustation ; and these crusts uniting, cement the whole into 
solid masses. Dogtooth spar is sometimes found crystallized in the cavities of this conglome¬ 
rate, on the shore of the Hudson, a quarter of a mile north of Washington valley, and one 
and a quarter from West-Point. The drift beds, composed of gravel, pebbles and boulders, 
are here, in places, cemented; although on casual inspection they might be considered loose. 
Large masses were seen on the shore, composed of these aggregated pebbles ; and on striking 
those of the cliff above, they were found to be solidified. Another locality is just above the 
stone culvert across the ravine, on the road from the wharf at West-Point to the plain. 
This formation of alluvial rock does not seem to extend far from the surface of the exposed 
cliflf, and is, in part at least, due to the evaporation of water containing the carbonate of lime 
in solution, which leaves the carbonate investing those objects from which the water has been 
evaporated. 
II. QUATERNARY DIVISION. 
This division embraces, in the First district, the clay, sand and gravel beds of the valleys of 
the Hudson and its tributaries; the valleys of Lake Champlain, and the streams that flow 
into it; and the more recent clay and sand deposits of Long, Staten and New-York Islands. 
Some boulders and drift deposits overlie this formation; but the main drift deposit, that is 
usually called diluvion, erratic block group, boulder system, etc., underlies this formation, 
and will be discussed in its proper place. 
This formation consists of three principal members, viz. sand, grey or buff-colored clay, 
and blue clay ; the sand forming the upper, and the blue clay the lower member of this di¬ 
vision. (Vide PI. 4, figs. 1,2; PI. 27, figs. 4, 5, 6, 7, 8, 9 ; and PI. 39, figs. 5, 6.) No 
fossil remains are known to have been found in this formation in the First Geological District, 
except the leaves of a small plant that were discovered in the blue clay in Albany, in the rear 
of the Medical College, by Dr. J. Eights. These leaves are brownish, but not decomposed. 
