403 The Upper Devonian Deposits of Maryland 



the Catskill formation. This is one of the best exposures of the formation 

 in Maryland and nearly all its layers are shown in a continuous section. 

 The dip varies from 62° at the base of the formation to about 30° at its top 

 which is near the farm house at the upper end of the narrow part of the 

 gorge. 



The lower rocks of the Catskill formation, immediately succeeding 

 the zone with Chemung fossils at the top of the Jennings formation, are 

 brownish-red to red sandstones alternating with thick bands of red 

 argillaceous shale. The lower half of the formation consists of nearly 

 all red sandstones and shales, sandstones predominating, and there are 

 but few bands of rather thin gi-cenish shales. In the upper half of the 

 formation coarse greenish-gray sandstones appear in the lower part in 

 rather thin bands alternating with the reddish rocks; but in the upper 

 portion there are thick zones of both greenish-gray sandstones and shales. 

 Some of the reddish sandstones also are more of a brownish-red color 

 near the top of the formation. All of the sandstones, as a rule, are 

 very micaceous and there is considerable cross-bedding. In general, it is 

 to be noted that in this section the reds, below the fossiliferous zone at 

 the top of the Jennings formation have a rather brownish tinge; then the 

 lower part of the Catskill is composed of quite red sandstones and 

 shales, while in the upper half of the formation there are zones of green- 

 ish-gray sandstone and shales of considerable thickness with brownish- 

 red sandstones near the top. The Catskill formation at this locality 

 was measured, from the base upward, by Dr. Eowe who estimated the 

 thickness of the section in three divisions as follows: 



lorizontal distance. 



A 



verage 



dip. 



Thickness, 



1097 





62° 







965 



838 





54° 







679 



753 





31° 







391 



Total 2688 









Total 



2035 



Dr. O'Harra gave the thickness of the Catskill for this section as 1900 

 feet.' The above thickness agrees very well with that of the Catskill 

 to the west of Hyndman, Bedford Coi;nty, Pa., which is about 10 miles 



' Allegany Co.. p. 109. 



