64 The Middle Devonian Deposits of Maryland 



of Corriganville wiiere 147 feet of the Eomney is exposed above which 

 about 30 feet is covered when the bhick, fissile shales of the Genesee appear 

 conspicuously azid these in turn are succeeded by the shales and sandstones 

 of the Woodmont. This is, probably, one of the best localities in western 

 Maryland for studying the change from the Eomney to the Jennings and 

 then the transition from the Genesee shale to the Woodmont member of 

 the Jennings formation. The actual contact of the Eomney and Jennings 

 formations occurs in the covered zone of 30 feet though the greater part of 

 it belongs in the Genesee shale as indicated by its thickness in other ex- 

 posures in Allegany County. The section at this locality is about as 

 follows : ' 



Total 

 Thick- thick- 

 ness, ness. 

 Beginning at the eastern end of the road cut there are bluish, 



arenaceous shales with some layers of thin sandstone, the latter 

 more conspicuous in the lower part of the exposure. The rocks 

 weather to a yellowish-green and are much iron-stained. The 

 upper part of this zone is more argillaceous, composed mostly of 

 thin shales and this portion is near the middle of the Hamilton 

 cut. Certain layers are fossiliferous, Spirifer mucronatus (Con- 

 rad) and other Hamilton species occurring. The strike is about 

 N. 35° E. and the dip 78° westward 80 80 



The succeeding zone consists of shales alternating with sand- 

 stones; one stratum of which reaches a thickness of 11 inches; 

 but in this locality the individual sandstone strata do not reach 

 so great a thickness as in some other exposures in western Mary- 

 land. Still the zone of sandstones which is generally found near 

 the top of the Romney formation is clearly represented 38 118 



The upper 29 feet of the Romney formation, so far as shown 

 in this cut, consists of thin, argillaceous shales in which Spirifer 

 mucronatus (Conrad) and Tropidoleptus carinatus (Conrad) occur 

 at the very top of the exposure 29 147 



Covered zone 30 177 



Black fissile shale of the Genesee in the base of the Jennings 

 formation 73 250 



Bluish thin shales alternating with sandstones of similar color. 

 One massive stratum with a thickness of 2 feet, 8 inches, is 

 succeeded by greenish shales alternating with thin sandstones. 

 These rocks which form the western part of the cut, the upper 

 portion of which is in the field at a distance of several feet from 

 the highway, are in the Woodmont member of the Jennings forma- 

 tion 230 480 



' All the sections in this chapter are described in reverse order, i. e., from 

 the bottom upward. 



