14 



NEW YORK STATE MUSEUM 



Grimes sandstone 



This formation, which attains a thickness of 75 feet, is an arenace- 

 ous band in which the sandstones are from an inch to more than a 

 foot in thickness and are separated by thin layers of dark bluish 

 gray shales, the greater frequency of the sandstones constituting 

 the principal difference so far as structure is concerned between it 

 and the Hatch shales below, as well as from the overlying beds. 

 In this quadrangle the formation is nowhere very well denned and 

 is much more obscure than farther to the west; consequently the 

 thickness here ascribed to it and the limits of the area over which 

 it is the surface rock are partly based on data derived from the ex- 

 amination of the formation farther west and by tracing it to this 

 vicinity. The rocks are exposed in the bed and sides of the Johnson 

 Hollow brook 1 mile west of Lower Pine valley, 920 to 960 feet A.T. ; 

 at the cascade in the upper part of Watkins Glen, 4 miles west of 

 Watkins below the second highway bridge west of the New York 

 Central Railroad ; the lower part at the top of the bank in the 

 Lehigh Valley Railroad cut, 1 mile west of Odessa. At Hammonds- 

 port the formation is well shown along the highway on the east side 

 at the head of Keuka lake near the top of the hill and in a ravine near 

 the corner of the road. In Grimes gully at Naples the sandstones are 

 at the crest of the Third falls, and a 4 inch blocky sandstone which is 

 one of the lower layers, contains several species of Ithaca brachio- 

 pods. This is their first appearance in that section above the Genesee 

 shale and the highest species of the Naples fauna occur a few feet 

 lower. In the Genesee river gorge the sandstones are in the cliffs 

 on the west side of St Helena and come down to the river level at 

 the mouth of Wolf creek but no representatives of the Ithaca fauna 

 occur iu them in that section. Still farther west the sandstones thin 

 out and are hot easily recognized except at the most favorable ex- 

 posures. They arc shown in Walnut creek ravine 1 mile south of 

 Silver Creek and in the cliff on the Lake Erie shore between Silver 

 Creek and Dunkirk. On the Watkins quadrangle in some small old 

 quarries in the bed and sides of the Johnson Hollow brook, I mile 

 west of Lower Pine valley, at 920 feet A. T., the following species 



