THE SUCCESSION OF FAUNAS IN THE PORTAGE AND 

 CHEMUNG FORMATIONS OF MARYLAND^ 



CHARLES K. SWARTZ 

 Johns Hopkins University 



In April, 1904, the author visited Great Cacapon, Western Mary- 

 land, in company with Messrs. Charles Butts, G. W. Stose, and George 

 C. Martin. At that time certain fossils were observed which, it was 

 believed, might indicate the presence of the Ithaca fauna in Maryland. 

 Subsequent and fuller investigations have been made which have con- 

 firmed this view.^ As the extension of the Ithaca fauna into this area, 

 had not been previously noted, it is believed that a brief presentation 

 of the results obtained may be of interest. A resume of the history of 

 the earlier investigations of the Upper Devonian formations of Mary- 

 land will be helpful in understanding the facts to be presented. 



HISTORICAL REVIEW 



In 1892 Mr. H. N. Darton proposed the name Jennings formation 

 for the Upper Devonian rocks which lie below the Hampshire, and 

 above the Romney in the Staunton, Virginia, quadrangle. ^ The 

 name was subsequently adopted by the Maryland Geological Survey 

 for similar strata in Maryland. 



A detailed study of the Upper Devonian formations of western 

 Maryland was made by Professor Charles S. Prosser, assisted by R. 

 B. Rowe, C. C. O'Harra, and others in the years 1898, 1899, and 1900. 

 The fossils collected were described by Dr. J. M. Clarke. A brief 

 statement of the results obtained was pubhshed by Professor Prosser 

 in the Journal 0} Geology in 1901.4 



It was shown that the Jennings formation in Maryland embraces 

 three members which are, in general, equivalent to the Genesee, Por- 

 tage, and Chemung of New York. ' ' 



1 Published by permission of the Maryland Geological Survey. ^ I ] 



2 A brief statement of this fact was published in Maryland Geol. Survey, Vol. V, 

 1905, and in the Johns Hopkins University Circular, New Series, No. 7, p. 50, 1907. 



3 American Geology, Vol. X, 1892, p. 17. 



4 Journal of Geology, Vol. IX, pp. 419, 420, 1901. 



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