374 
GEOLOGY OF THE FIRST DISTRICT. 
the Hudson-river group. It is composed of angular fragments of the siliceous and calciferous 
rocks of the lower part of the Champlain division, cemented together into a hard, tough, 
siliceous and sometimes a calcareo-siliceous breccia, that makes beautiful cabinet specimens 
of rich and variegated colors. Boulders of this rock are found in the valleys of the southeast 
part of Ulster county, and as far south as Hamptonburgh and Goshen in Orange county. 
At Eddyville in Ulster county, contortions of the slate rocks of the group under conside¬ 
ration are finely exposed to view in the banks of the Walkill (Vide Plate 9, fig. 11). 
Near Saugerties, in the banks of the Esopus creek, the rocks of the Hudson-river group 
are well exposed, upturned at a high angle, and in some places contorted. They are also 
exposed in many places between Saugerties and Kingston on the south, and Catskill on the 
north, and particularly between Saugerties and Bristol. 
Although the actual junction of the rocks of the Hudson-river group with those of the Hel- 
derberg division was not observed between Kingston and Catskill,‘they were seen in many 
places so nearly in contact, and unconformable, as to leave scarcely a doubt that they were 
really unconformable (Vide PI. 7, fig. 9 ; PI. 8, figs. 1, 2, 3, 7). The actual junction was 
seen only at Lawrence’s quarries opposite Wilbur (Vide PI. 26, fig. 1), and at Pine hill, both 
of which are near Kingston, and in both these places the strata were unconformable. 
The only supposable case, if these strata are not generally unconformable where the 
rocks have been deranged, is, that the anticlinal axis which ranges along the base of this 
long mural escarpment of the limestones of the Helderberg division, has caused all the 
strata of the Hudson-river group, over a breadth of many miles eastward from this cliff, to be 
upturned in a position nearly vertical, almost in contact with the limestones, which are but 
slightly elevated, dipping moderately to the westward, while the slate generally dips to the 
eastward. (Vide PI. 38, fig. 14, which is a section from Catskill westward to the stone bridge 
across the Kaaterskill; and fig, 13, near the mineral spring, three miles west of Athens in 
Greene county ; and Plate 11, fig. 13.) 
Numerous facts similar in character to these have been observed in several places along the 
anticlinal axis between Catskill and Sandyhill, where the slate rocks were nearly undisturbed 
on the west side of the anticlinal axis, while they were upturned at a high angle on the east; 
but the more numerous facts seem to demonstrate that these strata have been deranged by two 
(perhaps more) distinct, successive periods of disturbance, with a long interval of repose be¬ 
tween them; that one broke up the strata on the east side of this axis, afterwards the strata 
of the Helderberg division were deposited, and since then the upheaving action has occurred 
along this same line, that has elevated the strata of the Hudson valley, and given the westerly 
dip to those that were before horizontal. 
The rocks of the Hudson-river group may be seen well developed about Catskill, on the 
banks of the creek and of the Hudson, and in many of the hills where the surface is not 
covered by the quaternary formations, from Catskill to New-Baltimore, east of the anticlinal 
axis. The country is very hilly and broken, except the quaternary plains, and numerous in¬ 
teresting facts may be observed along the banks of the Hudson and of the tributary streams 
between those places, wherever the strata are exposed to view. 
