306 
GEOLOGY OF THE FIRST DISTRICT. 
The stream at these mills has cut a deep ravine or gorge, with sides that are perpendicular 
in some places, and a fine view of these rocks is thus exposed. Fucoids are found in these 
rocks, as also in a large portion of those in the section of the Catskill mountain, from No, 11 
to 131. Shells and terrene plants are found in the strata embraced in No. 132, The strata 
from No. 70 to 122 inclusive, are grouped in terraces. The strata above the shanty in 
the ravine half way up the mountain on the road from Catskill to the Mountain House, are 
not grouped on the section into terraces, on account of the difficulty of defining their limits 
in ascending along the road, which is, of course, made in the most favorable location; but 
at a distance from the mountain, where the eye can observe a greater area, the mountain is 
seen to be divided into regular terraces to its very summit. The series is capped by a quart- 
zose conglomerate, which may be seen well developed on the South mountain, south of the 
Mountain House. 
The road from Catskill to the Pine orchard, at which the Mountain House is located, ex¬ 
poses a large proportion of the rocks of the First geological district, and of the State, in the 
short distance of twelve miles, and crosses the main anticlinal axis of the Hudson valley. 
The Hudson river slate series is seen in part at Catskill, dipping at a high angle to the east- 
southeast, overlaid unconformably by the clay, sand, and gravel deposits of the Hudson 
valley. The Helderberg limestone series, with its peculiar fossils, is seen along the anticli¬ 
nal axis, very much broken up, and dipping in various directions ; but near the Caterskill, 
the limestone dips rapidly to the west, and is overlaid by the black Marcellus shales at the 
stone bridge on the road to the Mountain House. The Caterskill valley is here filled with 
the clay beds of the Hudson valley, so as to conceal the rocks ; but half a mile west, the 
rocks of the Erie division are seen in the high hill dipping at about the same angle, but gra¬ 
dually diminish in the angle of dip as we approach the mountain. This part of the series 
can be examined satisfactorily, only, by following up the bed of a s tream near which the 
turnpike passes. These strata are of probably one thousand feet in thickness, and are em¬ 
braced on the section in No. 132. 
From Caterskill creek, the strata emerge in a succession of terraces, with a steep, bold 
escarpment on the east; but they slope away gradually to the west, until at the base of the 
mountain, the rocks seem to be horizontal. Each terrace is capped by a hard grit, or other 
rock that has been able to resist the action of the weather and water. The mountain, when 
viewed from a distance, has the appearance of rising by successive steps. Each terrace 
from the bottom upward is nearly level, but they are narrow near the top of the mountain. 
Although the strata on the mountain seem to the eye to be horizontal when viewed near, 
they are evidently not so when seen at a distance where the eye can at once grasp a great 
extent in view, and trace the particular strata and terraces along the front of the mountain 
and up the various valleys. They are seen to dip at a slight angle to the southwest. 
The strata on the section of the Catskill mountain from 11 to 132, are generally from ten 
to fifty feet thick each ; some few are thinner, but the aggregate cannot be much less than four 
thousand feet for those strata, unless there should prove to be faults, that may have caused 
