DEPARTMENT OF THI-: INTERIOR 

 UNITED STATES GEOLOGICAL SUIiVEY 



GEORGE OTIS SMITir, Dirkctoe 



PlJOFKSSIOXAT. PAPF.K 71 



INDEX TO THE STRATIGRAPHY 

 OF NORTH AMERICA 



BAILEY WILLIS 



ACCOMPANIED BY A 



GEOLOGIC MAP OF NORTH AMERICA 



COMPILED BY THE UNITED STATES GEOLOGICAL SURVEY IN COOPERATION WITH THE 



GEOLOGICAL SURVEY OF CANADA AND THE INSTITUTO GEOLOGICO DE MEXICO 



UNDER THE SUPERVISION OF BAILEY WILLIS AND GEORGE W. STOSE 



