134 The Lower Devonian Deposits of Maryland 



containing very few fossils. Great numbers of cystids have been found in 

 the strata between 90 and 133 feet above the base of the Keyser. This is 

 a local development of the rich cystid fauna which makes this locality of 

 great interest. The Gyp-ldula coei/manensis var. yrognosiica zone is at about 

 the same altitude at which it is found in the other sections in the Cumber- 

 land region. The Gypidula become so large and so closely approach 

 Gypidula coeymanensis of the Coeymans member that they are very diffi- 

 cult to distinguish. A conspicuous feature of the upper part of the Keyser 

 member is the thick zone of coral which lies 186 feet above the base. This 

 zone is overlain by more shaly beds containing Tentaculites gyracanthus, 

 Schuchertella prolifica, and Merisiella prcenuntia in profusion. The 

 upper strata are banded, much less fossiliferous, and resemble the Tonolo- 

 way in their lithological features. It is difficult to collect fossils in the 

 Coeymans and Xew Scotland members although they are well exposed.' 



Helderberg Formation Vertical Total 



thickness vertical 



Coeymans Member ^'^"^ thickness 



Massive crinoidal limestone very fossiliferous. 



Keyser Member 

 Thin to medium-bedded gray limestone, nearly unfossiliferous 

 throughout, with fine brown lines. Leperditia altoides 21.7 . . . . 17.3 281.0 



Compact gray limestone, thin-bedded. At top of unit occur Le- 

 perditia altoides (a), Meristella prcenuntia, Nucleospira sp., Un- 



cinulus sp. At h&se occurs Liocle ma subramosum 3.4 263.7 



Gray crystalline limestone 0.8 260.3 



Heavy-bedded gray limestone with many transverse calcite 

 seams. Meristella prwnuntia var. small, Spirifer vanuxemi var. 

 prognosticus, Lioclema subramosum 256.7', Schuchertella pro- 



lifica 234.5 29.2 259.5 



Shaly limestone containing fossiliferous crystalline layers. 

 Weathers more easily than the adjoining units. Schuchertella 

 prolifica and Tentaculites gyracanthus occur in abundance at 

 223.1, 223.5, 225.1, 226.1, Meristella prwnuntia, abundant 223, 

 225.1, Uncinulus Jceyserensis 223.1, 225.1, Uncinulus nucleo- 

 latus ? 225.1, Lioclema subramosum 223.5, 225.1 7.2 230.3 



'The numbers after names of fossils indicate the altitude in feet at which 

 they occur above the base of the formation. 



