202 



HISTORICAL GEOLOGY 



Fig. 119 

 Map showing the surface distribution (areas of outcrops) of Triassic and 

 Jurassic strata in North America. Some areas of doubtful age and extent 

 not shown in British Columbia. All Atlantic Coast areas are Triassic. In 

 much of the western United States the Triassic and Jurassic have not yet 

 been satisfactorily separated. (By W. J. M., data from two maps by 

 Bailey Willis, U. S. Geological Survey.) 



