228 On the Lertiary Formations of ihe Hudson. 
60° with the strata; colour bluish green, sometimes red ; 
some of the varieties are made use of for roofing, others com- 
pact slate, pencil slate; frequently contains veins of quartz, 
and rarely thin beds of coal; sometimes passes into jasper 
slate, and alternates with transition limestone, containing the 
usual fossils. 
Immediately super-imposed upon the transition clay slate, 
are the tertiary strata, consisting of an extensive deposi 
tion of 
Clay Marl, containing from 12 to 15 per cent. of carbo- 
nate of lime, colour blackish blue, bluish gray ; sometimes 
contains iron pyrites and fossil wood, varies in thickness from 
10 to 60 or 80 feet; the original deposition was probably of 
a uniform thickness, and the irregularities of its surface may 
have been produced by diluvian torrents. 
Adhesive Slate forms large beds in the preceding stratum, 
colour yellowish gray, grayish white ; particles of it adhere 
to the fingers ; it occurs in laminz, varying in thickness from 
half an inch to six inches; fracture earthy; when dry, con- 
choidal. Used extensively in the manufacture of bricks. 
Clay sometimes occurs in large beds, in the clay marl, or 
eccupies its place, colour various. 
Diluvial is the highest of these formations, and is distin- 
guished, as in every part of the earth’s surface, by sand and 
gravel, containing detached pebbles of the older rocks. 
At Newburgh, the diluvial strata form numerous rounded 
eminences which may be traced to some distance in the coun- 
try. South of the town, the clay appears at the surface. 
One mile north, on the shore of the river, is adhesive slate. 
At Fishkill Landing, on the opposite shore, the adhesive 
slate forms a continuous stratum, extending near two miles. 
Near Marlborough the clay marl predominates. 
At Hyde Park, near the residence of Dr. Allen, the clay 
marl makes its appearance, about half way down the declivity 
of the hill, but it may be seen to more advantage on the 
estate of Wm. Bard, Esq. immediately on the shore of the 
river, and adjoining the property of the Hon, Judge Pendle- 
ton. When exposed to the action of small torrents of 
water, the marl assumes various singular forms, and 
becomes indurated by exposure to the air. These fi- 
gured marls occur in various other places, near the North 
river, and have been described in the Americal Journal of 
Science. The diluvial %rata at Hyde Park, are distinguished 
