BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 16, pp. 329-346 May 29, 1905 



CORRELATION OF MARYLAND AND PENNSYLVANIA 

 PIEDMONT FORMATIONS* 



BY EDWARD BENNETT MATHEWS 



(Read before the Society December SO, 1904) 

 CONTENTS 



Page 



Introduction 329 



Formations of the Piedmont 330 



List of the formations 330 



Baltimore gneiss 330 



Setters quartzite 332 



Cockeysville marble 334 



Wissahickon formation 335 



Cardiff quartzite 338 



Peachbottom slates 338 



Age of the formations 339 



Structure and structural relations of the Piedmont formations 339 



Eastern Piedmont of Virginia 344 



Conclusions .• 34G 



Introduction 



The generalizations and conclusions presented in the present paper are 

 based on the detailed work of the writer and his assistants on the Mary- 

 land Geological Survey, covering the territory from the Susquehanna 

 river to longitude 76 degrees 50 minutes, with the exception of a small 

 area in the immediate vicinity of Baltimore, and on the lines determined 

 by the late Professor Williams, confirmed by a rather detailed recon- 

 naissance by the author, on the territory west of this line to the area of 

 the Frederick and West Washington sheets, where the work of Mr 

 Keith, supplemented by reconnaissance work by the author, is used. 

 The writer has also had access to the field notes, manuscript material, 

 and microscopic sections of Professor Williams, which were prepared by 

 him during his work on the United States Geological Survey. The con- 

 clusions reached from the information received from these various sources 

 are, however, the work of the writer, who alone is responsible for them. 



♦Published by permission of the Maryland Geological Survey. 

 XLIV— Bm.i.. Geoi,. Sor. Am.. Vol. 16, 1904 (329) 



