356 
GEOLOGY OF THE FIRST DISTRICT. 
the water limestone and the quaternary deposits of the Hudson valley.* On the higher parts 
of the Shawangunk mountains, it generally lies in nearly horizontal strata, often thick-bedded, 
and presenting mural escarpments of broken ends of the strata thirty to two hundred feet 
high. Some places on the eastern face of the mountain present the strata with a high dip to 
the east-southeast; but on the western face, the dip is almost uniformly to the west-northwest 
at variable angles. That part of the range about Wurtsboro’, Ellenville and Wawarsing, 
shows a dip from thirty to sixty degrees to the west and northwest; but with some local 
exceptions, the dip of the grit rock towards either extremity of the range is less, and does 
not generally exceed eight to fifteen degrees. 
The thickness of the Shawangunk grits is variable, but its maximum is belieyed to be less 
than five hundred feet, and its usual thickness is from sixty to one hundred and fifty feet. 
The strata are traversed by two great systems of fracture ; one longitudinal, and approach¬ 
ing more or less to the direction of the strike; the other transverse. Their usual directions 
are S. 20° W. and N. 20° E. for the first, and S. 60° E. and N. 60° W. for the second. 
The Shawangunk mountains are less broken than any others with which I am acquainted, 
and which have been upheaved along an axis of elevation; but several breaks may be ob¬ 
served in them. These mountains continue, with but slight breaks, from the New-Jersey line 
near Carpenter’s point, to opposite Ellenville and Wawarsing in Ulster county, where this 
ridge is crossed by great breaks and faults. The ridge then sinks and rapidly disappears be¬ 
neath the valley, while several wrinkles or subordinate parallel axes of elevation spring up on 
the east at about the same height; run northeastward between the Stony kill, Mule kill, San¬ 
ders kill, &c,, sink down gradually towards the mouths of those streams, and finally disappear 
below the valley in Rochester and Marbletown, or show their continuation only by low broken 
ridges of upheaved limestone. .These axes of elevation are terminated, apparently, on the 
south, by the high cliffs along the transverse lines of fault. On the east of these minor axes, 
the second main axis of elevation takes its rise from High point, which is a high cliff of grit 
rock on the main fault, and ranges thence northeaistward, more or less broken and dislocated 
by minor transverse and oblique faults, and diminishing in height, until the Shawangunk moun¬ 
tain and its grits, which envelope most of the higher parts, entirely disappear below the lime¬ 
stones and quaternary deposits at and near Rosendale. Several high points with mural fronts 
and ends are seen between Highpoint and Springtown, as Sam’s point. Great Mogunk, Buntico 
point, &c., all of which are caused by faults along the main fractures of the mountain. 
It has been mentioned that the wrinkles, or subordinate axes of elevation, seemed to termi¬ 
nate at the high rocky points on the southeast side of the Shawangunk mountain, as High 
point, Buntico point, Sam’s point. Great Mogunk, &c. The termination is only apparent, 
caused by the transverse fractures. The ridges almost all slope down to the north and north- 
* This rock extends across a part of New-Jersey, from Carpenter’s point to the Wallpack bend of the Delaware, where it en¬ 
ters Pennsylvania, ranges entirely across that State, Maryland and a part of Virginia, forming high mountains in many places; 
Its characters, both lithological and organic, are very constant over this long belt of country. 
