514 C. SCHUCHERT CHRONOLOGY ON BASIS OF PALEOGEOGRAPHY 



The Cretaceous period and the Mesozoie era were closed by the Lara- 

 mide Eevolution. The area of folding and thrusting embraced the 

 mountains of western North America, the Antillian region, and the Andes 

 of South America — two grand mountain chains that extended from Cape 

 Horn to Panama and from southern Mexico far into Alaska. Volcanic- 

 activity began late in Cretaceous time and continued into the Eocene, 

 and the volcanoes extended from Mexico City and Arizona north far into 

 Canada. 



In conclusion, let me add that I have pointed out only the broader 

 events and the general paleogeography. The more interesting detail and. 

 the actual ancient geography remain as the work of the rising generation 

 of west coast geologists and paleontologists. 



