PORTAGE AND CHEMUNG FORMATIONS OF MARYLAND 329 



The fossils described from the Portage were those characteristic of 

 the Naples fauna of New York.^ A thickness of approximately 2,000 

 feet was assigned to it in the central part of the area studied.^ 



All strata from which brachiopods were described were assigned 

 to the Chemung. This fauna was known to contain two elements, 

 one characteristic of the Ithaca fauna and another of recognized Che- 

 mung facies, while the two elements were supposed to be commingled 

 in the Chemung of Maryland. 



The Jennings, though comprising diverse elements, was mapped 

 as a unit because it was deemed impracticable to attempt a carto- 

 graphic separation of its members at that time. 



It appears from the work here discussed that a considerable number 

 of the species previously referred to the Chemung of Maryland occur 

 in reahty in the Ithaca facies of the Portage formation. The number 

 of species thus far observed in it is not large, but they are represented 

 by a profusion of individuals. 



The various sections will be discribed, those in Washington County 

 being first considered, then those in Allegany County, adjoining it 

 on the west; their faunules will be analyzed, and the correlation of the 

 faunules with those of New York will be finally discussed. 



The present article is a preliminary discussion of the results 

 obtained. The author wishes to acknowledge his indebtedness to 

 Mr, D. W. Ohern, Fellow in Johns Hopkins University, for much 

 assistance, particularly in mapping the divisions in Allegany County, 

 and in the measurement and detailed study of a number of the sections. 



SECTIONS IN WASHINGTON COUNTY 



The Genesee is absent in Washington County. 



Great Cacapon.— This section is situated north of the Potomac River 

 opposite Great Cacapon, West Virginia, 8^ miles southwest of Han- 

 cock, Md. The strata are well exposed in the cut of the Western 

 Maryland Railroad, standing nearly vertical. They comprise the 

 Portage and part of the Chemung. The base of the Jennings is well 

 marked, on the east, by a massive sandstone which forms the top of 

 the Romney, and which contains Hamilton fossils. 



1 Journal of Geology, Vol. IX, p. 420. 



2 Maryland Geological Survey, Vol. VI, Part I, p. 136, 1906. 



