BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 14, pp. 277-296 AUGUST 5, 1903 



GEOGRAPHIC DEVELOPMENT OF NORTHERN PENNSYL- 

 VANIA AND SOUTHERN NEW YORK* 



BY MARIUS R. CAMPBELL 



[Read before the Society December SO, 1902) 

 CONTENTS 



Page 



Introduction •. 277 



Description of the region , . 278 



Interpretation of surface features 281 



Physiographic features of eastern Pennsylvania 282 



Somerville peneplain 288 



Harrisburg peneplain. 283 



Shenandoah valley 283 



Delaware valley 284 



Schuylkill valley 286 



Susquehanna valley 286 



Potomac valley 288 



Upper Potomac valley 289 



Upper Susquehanna valley 290 



Ohio valley 292 



Deformation of the Harrisburg peneplain 295 



Resume 295 



Introduction 



The surface features of northern Pennsylvania and southern New 

 York consist in a broad way of an elevated plateau so extensively dis- 

 sected that only small remnants remain here and there of what appears 

 to have been once a fairly even surface. Although this country is readily 

 accessible, and is familiar to many of our leading physiographers, no 

 attempt so far has been made to unravel its physiographic history. 

 Beyond a brief reference by Davis f and Tarr % of the surface of this 

 plateau to the Cretaceous peneplain, nothing has been done in the way 



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



fThe geologic dates of origin of certain topographic forms on the Atlantic slope of the United 

 States. Bull. Geol. Soc. Am., vol. 2, p. 566. 

 X Physical geography of New York state, p. 102. 



XL— Bull. Geol. Soc. Am., Vol. 14. 1902 (277) 



