68 PENNSYLVANIA AND NEW YOKE DEVONIAN. [bull. 120. 
the Catskill Mountains to G-lasco, Ulster County, and gave the thickness 
of the different formations as follows: "The lower beds shown, of Port- 
age and Chemung, have a thickness of more than 2,000 feet; while the 
red rocks above, which maybe referred to the Catskill, are about 3,000 
feet thick, and the higher beds, of Vespertine, extending to the summit 
of Bound Top, may be reckoned at about 800 feet." 1 
The ledge in front of the Catskill Mountain House, overlooking the 
Hudson, is the coarse gray sandstone of the Catskill stage, as stated in 
1843 by Mather. 2 Mr. N. H. Darton has published a section "west of 
Palenville," on which the lower dark shales are called "Hamilton 
group," with the "Oneonta beds" immediately above, on which rests 
the "Catskill group." 3 
In the text it is stated that the Chemung "becomes harder and 
coarser eastward, and was traced to and along the eastern front of the 
Catskill Mountains, its base defining the upper limit of the Oneonta 
formation. Its thickness averages about 250 feet. It is overlain by a 
red shale bed 25 to 30 feet in thickness, and this, in turn, is overlain by 
the thick mass of hard gray sandstone on which the old Mountain 
House is built. At a point about 4 miles due west of Durham, some 
molluscan remains, were found in a softer gray bed about 175 feet above 
the summit of the Oneonta formation. One fairly distinct individual 
was recognized by Dr. Hall as Spirifer disjuncta, a Chemung form." 4 
Near the summit of the path from the Mountain House to the Hotel 
Kaaterskill, over South Mountain, is a ledge of very coarse conglom- 
erate, which is similar to the one in Twilight Park on Round Top, 
However, it is some 375 feet higher, considering the ledge in front of the 
Mountain House 2,225 feet A. T. 5 On the road toward the Hotel Kaat- 
erskill, after the path enters it, is a small ledge composed in the center 
of a conglomerate layer, with gray sandstone above and below. Toward 
the hotel the conglomerate thickens rapidly, making an excellent locality 
for noting the rapid change in the thickness of a conglomerate. The 
strata on South Mountain are nearly horizontal, but in places there is 
very strong cross-bedding. Guyot clearly described the structure of 
the Catskill Mountains as follows: "We have not to look in the chains 
of the Catskill for a series of anticlinal and synclinal folds or arches, as 
in ordinary mountain chains. Throughout the region the strata of 
which they are composed are nearly horizontal from the bottom of the 
valleys to their top, or have a dip rarely exceeding 1° or 5°. The same 
is true of the plateaus." 6 
On the bank of the Kaaterskill Creek below Etna Cottage, east of 
'Proc. Am. Assoc. Adv. Sci., Vol. XXIV, B, pp. 82, 83. For additional particulars see 28th An. Rep, N. 
Y. State Mus. Nat. Hist., pp. 14, 15. 
2 Geol. N. T., Pt, I, p. 303. 
3 Am. Jour. Sci., 3d Ser., Vol. XLV, p. 205, section D of tig. '_'. 
4 Op. cit., p. 207. 
6 Guyot, Am. Jour. Sci., 3d Ser., Vol. XIX, p. 449; and this conglomerate ledge is barometrically 150 
feet higher. 
6 Ibid., p, 433. 
