MzVRYLAND Geological Survey 187 



VIII. Section at Tonoloway 

 The Oriskany sandstone is well exposed in the cut of the Western Mary- 

 land Railroad at Tonoloway, opposite Great Cacapon, West Virginia. The 

 following section was measured by G. W. Stose and E. 0. Ulrich.' 



RoMNEY Formation 



Vertical Total 

 Onondaga Member thickness vertical 



" feet tliicliness 



Black and drab shale. 



Oriskany Formation 



Ridgely Member 



Soft, porous, brown fossiliferous sandstone, some beds a fine 

 dark vitreous quartz conglomerate. Very fossiliferous layer 



at base 40.0 417.0 



Massive beds, 10-20 feet thick, of white fossiliferous quartzose 



sandstone 85.0 377.0 



Softer, thinner-bedded, fossiliferous sandstone, weathering 



yellowish 90.0 292.0 



Hard, quartzose sandstone 2.0 202.0 



Soft, thin-bedded, yellowish sandstone. Few fossils 45.0 200.0 



Covered. Soft sandstone debris 140.0 155.0 



Thickness of Ridgely member 412.0 



Shriver Chert Member 



Yellow, probably calcareous, fossiliferous shale with much 

 chert, containing Oriskany fossils 15.0 15.0 



Thickness of Oriskany 417.0 



Helderbeeg Formation 

 'Mew Scotland Member 

 Residual clay often limestone filled with white blocky chert. 

 Fossiliferous 12.0 



The thickness of the Oriskany at this locality is greater than that 

 observed elsewhere in Maryland. The usual thickness in the Cumberland 

 area is about 350 feet, while on Elbow Ridge, but 15 miles northeast of 

 this place, it is but 52 feet thick. The beds also change from a calcareous 

 sandstone near Hancock to an arenaceous limestone in the eastern section. 



1 Pawpaw-Hancock Folio, U. S. Geol. Survey, 1912, p. 9. 



