THE MIDDLE DEVONIAN DEPOSITS 

 OF MARYLAND 



BY 

 CHARLES S. PROSSER, E. M. KINDLE, AND C. K. SWARTZ 



INTEODUCTOEY ' 



The Paleozoic time divisions — Cambrian, Ordovician, Silurian, De- 

 vonian, Carboniferous and Permian — which are called periods by the 

 International Congress of Geologists and the United States Geological 

 Survey and eras in Dana's Manual of Geology ^ were frequently divided 

 in a general way into lower, middle, and upper divisions while the terms 

 earlier and later were sometimes used. In 1894, Prof. Henry S. Williams 

 proposed that this two- or three-fold division should be designated by 

 prefixing the syllables Eo (dawn), Meso (middle), and Neo (new) to 

 the name of the period.' Later, the syllable Paleo (ancient), has been 

 substituted by some authors for Eo.^ The Devonian formations were 

 distributed bv Professor Williams under these three divisions in the 

 following manner: The Eoderonian contained the Oriskany sandstone, 

 Cauda galli (Esopus) and Schoharie grits and Corniferous or Onondaga 



' Contributed by Charles S. Prosser. 



- In general the taxonomic terms of the International Congress of Geologists 

 will be used in this report. Frequently, however, the term beds is used instead 

 of stage, as Hamilton, Portage, or Chemung beds, a term of similar taxonomic 

 value used by Messrs. Clarke and Schuchert in their descriptions of certain 

 New York formations. 



^ Jour. Geology, Vol. II, p. 157, and see table on p. 155. 



* Clarke and Schuchert, Science, N. S., Vol. X, Dec. 15, 1S99, p. 876; and 

 Am. Geologist, Vol. XXV, 1900, p. 118. 



The International Congress of Geologists at the Paris meeting of 1900 

 adopted the prefix Paleo, but stated that Eo may be used to shorten too long 

 a name (Comptes Rendus, 8th Session, 1901, pp. 153, 198). 



