Marylaxd Geological Survey 411 



parts of Pennsylvania and West Virginia, in order to establish a series 

 of persistent litholooical and fannal horizons, and then to correlate the 

 divisions so established with the strata of other regions. The subject will 

 be discussed under the headings: Lithological and faunal subdivisions. 

 Correlation. 



LITHOLOGICAL AND FAUNAL SUBDIVISIONS 



An examination of the local sections shows that the Jennings 

 formation of ]\Iaryland is divisible into four members which are distinct 

 both lithologically and faunally. The members are further subdivided 

 into a number of lithological divisions, and faunal zones as shown in the 

 following table : 



JENXINGS rOEMATIOX. 



Chemung sandstone member. Spirifer disjunctus fauna. 



Upper sandstone and shale. Camarotoechia eximia zone. In the central 

 part of the area these beds comprise three divisions. 

 Beds of recurrent Jennings type with a marine fauna. Palseanatina 



angusta zone. 

 Red beds of Catskill type. 

 Beds of Jennings type with a marine fauna. 

 Upper Chemung conglomerate. 

 Middle sandstone and shales. 



Lower Chemung conglomerate, Tropidoleptus carinatus zone. 

 Lower sandstone and shale, Dalmanella tloga zone In west. 

 Parkhead sandstone member. Recurrent Tropidoleptus carinatus fauna. 

 Shale beds. 



Conglomeratic sandstone beds. 

 Cyclonemina multistriata zone. 



Camarotcechia congregata var. parkheadensls zone. 

 Liorhynchus mesacostale zone. 

 Woodmont shale member. 



Beds containing Ithaca fauna. (ISpirifer mucronatus var. posterns 

 fauna). 

 Liorhynchus globuliforme zone. 

 Cladochonus-Reticularia laevis zone. 

 Beds containing the Naples fauna (Buchiola speciosa fauna). 

 Genesee black shale member. 



Genesee Blade Shale Member 



Chailvcter AND THICKNESS. — The Genesee member consists of fissile, 

 black, argillaceous shale, characterized by breaking into large flat sheets 



