173 The Lower Devoniax Deposits of Maryland 



Vertical Total 

 OBISKANY Formation thickness vertical 



feet thickness 



Top Of Knobly Mountain, concealed 110.0 320.0 



Heldeebekg Formation 

 ^evo Scotland, Coeymans and Keyser Members 

 Light gray massive limestone with bands of light colored 

 chert at the top 210.0 210.0 



The upper part of the New Scotland member stands out in a bold cliflf 

 near the very top of the mountain. The fossils are shown here along its 

 upper surface as at Eiverside, including: Spirifer macropleurus, S. 

 perlamellosus, Meristella arcuaia, Nucleospira ventricosa, Schuchertella 

 ivoohvorthana, Stropheodonta hecki, Eaionia medialis, and Uncinuhis 

 abruptus. 



The Helderberg formation is exposed on the west side of KJnobly Moun- 

 tain at Miller's Spring, immediately south of the tunnel of the Western 

 Maryland Eailroad. The occurrence of fossils in the Keyser member at 

 this place has already been discussed. The following fossils were obtained 

 by Eowe from loose blocks of New Scotland limestone, at this locality: 

 Atrypa reticularis (rr), Spirifer perlamellosus (c), Strophonella leaven- 

 worthana (rr), Leptcenisca concava (rr), Leptcena rJiomhoidalis (aa), 

 Schnchertella woolworthana, Chonetes subacutiradiahis (rr), Dalmanella 

 perehgans (rr), Ehipidomella ohlata (r). 



VI. Section at Devil's Backbone 

 This locality affords one of the finest sections of the Helderberg forma- 

 tion in the entire State. An uninterrupted exposure extends from the base 

 of the Keyser member to the top of the New Scotland limestone. The 

 section described ' is continuous with that of the Keyser member given 

 on a preceding page to which reference should be made for a further 

 account of this locality. It is also continuous with the section of the 

 Oriskany given on a subsequent page. 



^ Measured by C. K. Swartz and assistants. The figures following the names 

 of the fossils indicate the altitude in feet above the base of the units at which 

 they were found. 



