BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 VOL. 16, PP. 289-328, PLS. 48-64 MAY 27, 1905 



PIEDMONT DISTRICT OF PENNSYLVANIA* 



BY F. BASCOM 



(Read before the Society December 30, 1904-) 

 CONTENTS 



Page 



Geography of the Piedmont 290 



General relations 290 



Local relations 291 



Geology of the Piedmont 292 



General geology 292 



Sedimentary series of the southeastern belt 293 



Pre-Cambrian rocks : Baltimore gneiss 294 



Distribution 294 



Character of the formation and stratigraphic relations 294 



Thickness, correlation, and name 296 



Cambrian rocks : Chickies quartzite 296 



Distribution 296 



Character of the formation 296 



Stratigraphic relations 298 



Thickness 298 



Correlation and name 298 



Cambro-Ordovician rocks : Chester Valley limestone 298 



Distribution 298 



Character of the formation 299 



Stratigraphic relations. . . 299 



Thickness 300 



Correlation and name 300 



Ordovician rocks : Wissahickon mica-gneiss (mica-schist and mica-gneiss) . 30L 



A real distribution 301 



Distribution of mica-schist 301 



Character of the formation and stratigraphic relations , 301 



Thickness 302 



Distribution of the mica-gneiss 302 



Character of the formation and stratigraphic relations 303 



Thickness of the mica-gneiss 305 



Name 305 



Stratigraphic relations 305 



Correlation 306 



Structure of the sedimentary formations 30(i 



* Published by permission of the Director of the U. S. Geological Survey. 

 XXXIX-Bui.i.. Geol. Soc. Am., Vol. 16, 1904 (289) 



