BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 2, pp. 301-322, PL. 12 



THE PETROGRAPHY AND STRUCTURE OF THE PIEDMONT 

 PLATEAU IN MARYLAND 



GEOKGE HUNTINGTON WILLIAMS OF JOHNS HOPKINS 

 UNIVERSITY 



WITH A SUPPLEMENT ON 



A GEOLOGICAL SECTION ACROSS THE PIEDMONT PLATEAU IN 



MARYLAND 



BY 



CHARLES R. KEYES 



QOCT 15 sC^ 





'v> .**: 



ROCHESTER 



PUBLISHED BY THE SOCIETY 



March, 1891 



