New York State Education Department 



New York State Museum 



John M. Clarke, Director 



Bulletin ii8 



PALEONTOLOGY 18 



GEOLOGIC MAP AND DESCRIPTIONS OF THE 

 PORTAGE AND NUNDA QUADRANGLES 



INCLUDING A MAP OF LETCHWORTH PARK 



BY 



JOHN M. CLARKE AND D. DANA LUTHER 



ACCOMPANIED BY A REPORT ON THE 



PLEISTOCENE HISTORY OF THE GENESEE VALLEY 



BY 



HERMAN L. FAIRCHILD 



GEOLOGY OF THE PORTAGE AND NUNDA 

 QUADRANGLES 



INTRODUCTION 



The region whose geological structure is here described in detail 

 is not alone celebrated in the history of New York geology for the 

 completeness of its presentments, the uniformity of its strati- 

 graphy and the fullness of its ancient faunas, but its human 

 history is romantic and its scenic features singularly attractive. 

 The Nunda and Portage quadrangles cover a territory 17 miles 

 long from north to south and 26 miles wide, through which 

 in winding course runs the great gorge of the Genesee river, 

 extending from Portage down to Mount Morris, a distance of 18 



