178 The Lower Devonian Deposits of Maryland 



infiltrating waters of the calcareous cementing material and its replace- 

 ment by a siliceous cement. This sandstone was long believed to be 

 Oriskany and mapped as such. Later it was considered New Scotland by 

 Rowe ' and Ulrich and Stose." It has more recently been shown to be of 

 Coeymans age by Swartz who found a characteristic Coeymans fauna in it. 

 The following fossils were collected on the road crossing the crest of Elbow 

 Ridge just south of the Maryland-Pennsylvania line : Gypidula coeyma- 

 nensis (a), Leptcena rliomhoidalis (a), StropJionella punctifera, Rhipido- 

 mella oblata ?, Dalmanella sp., Plewodictyum lenticulare, Favosites 

 helderbergice. It is interesting to note that a thin sandstone occurs near 

 the base of the Coeymans at a number of localities west of Cumberland, a 

 feature best seen at Dawson. 



IX. Section at Ernstville 

 At Ernstville ojiposite Cherry Run, about one-half mile north of the 

 canal, is an abandoned quarry in which the upper part of the Helderberg 

 and the Oriskany are shown. There is a broad, low anticline which strikes 

 across the river at this place appearing along the Baltimore and Ohio 

 Railroad on the south side of the Potomac, a short distance west of Cherry 

 Run. It then disappears rapidly beneath the younger rocks to the south- 

 ward. The section is as follows, according to the measurements of R. B. 

 Rowe: 



Helderberg Formation 



Vertical Total 

 Becraft Memier thickness vertical 



feet thickness 

 Light gray massive limestone with many chert bands. Fos- 

 siliferous. Spirifer concinnus (rr) , Rensselrrria suhglobosa (r), 

 SchucherteTla woolivorthana (a.a.) , Rhipidomella oblata (a).... 20.0 42.0 



Dark bluish-gray massive limestone with occasional layers of 

 black shale. Limestone layers are about 4 feet thick with shale 

 beds between. Very fossiliferous. In massive layers and 

 nodules of chert are Spirifer cyclopterus (aa), S. perlamellosus 

 (r), Nucleospira ventricosa (c), Uncinulus vellicatus (a), 

 Eatonia singularis (rr), PletJiorhyncha prwspeciosa (r), Lep- 

 Uvna rliomhoidalis (a), Rhipidomella oblata (r), Edriocrimis 

 pocilliformis (aa), Streptelasma striatum (r), Aulopora scho- 

 hariw 22.0 22.0 



Thickness of Becraft member exposed 42.0 



^ Lower Devonian of Maryland. Dissertation for degree of Doctor of 

 Philosophy in the Johns Hopkins University. 

 = Pawpaw-Hancock Folio, U. S. Geol. Survey, 1912. 



