Maryland Geological Survey 147 



Horizontal Vertical Total 

 distance thickness vertical 

 teet feet thickness 



Heavy-bedded limestone weathering like the above 



unit. Stenochisma sp., Atrypa reticularis 56.0 6.1 50.4 



Concealed. 



On the hillside in this unit were found Chiloirypa 



micropora, Fcnestella (Cycloporina) altidorsata. Or- 



thopora rhombifera, Polypora dictyota, Atrypa reticu- 

 laris, Dalmanella clarki (aa), Camarotachia litchfield- 



ensis, Stenochisma deckerensis, Spirifer modestus. S. 



eriensis (rr), Lojonema sp., Tentaculites gyracanthus. 



Leperditia sp., Aulopora sp., crinoids 49.4 7.8 44.3 



Purplish-blue argillaceous, heavy-bedded limestone. 40.8 1.5 36.5 



Concealed 39.0 13.8 35.0 



Grayish-blue massive limestone with crinoids, bryo- 



zoa, Stropheodonta sp 24.0 1.4 21.2 



Concealed 22.3 9.2 19.8 



Crinoid bed, crinoids extending through the whole 



bed 12.3 6.9 10.6 



Concealed 4.7 2.0 3.7 



Heavy blue-gray limestone 2.0 1.7 1.7 



The remainder of this section is concealed. 



Thickness of Keyser member exposed 130.4 



The following fossils have also been found in this section, their precise 



horizon being unknown : 



Cyphotrypa corrugata. Schuchertella deformis. 



Carnarotoechia gigantea. Stropheodontageniculata, Lower beds. 



Dalmanella concinna. Lower beds. Uncinulus convexorus, Lower beds. 



Merista typa, Lower beds. Wilsonia globosa. 



Aulopora schucherti. Actinopteria communis. 



Halysites catenulatus. Bellerophon helderbergiae. 



Nucleospira swartzi. Platyostoma sp. 



VIII. Section at Devil's Backbone 



The Devil's Backbone is locally so-called because one of the heavy beds 

 at the top of the Coeymans stands out at this place as a marked topographic 

 feature resembling somewhat a backbone in appearance. This ridge is 

 the first prominent one on the west side of the Wills Mountain anticline 

 and is formed of Helderberg and Oriskany strata. 



The Helderberg is well exposed by the cutting of Wills Creek, which 

 flows approximately parallel to the west side of the ridge from above the 

 Maryland-Pennsylvania line until it is joined by Jennings Run at Corri- 

 ganville where it makes a sharp turn to the southeast and cuts across the 



