CHAPTER XXV 
MESOZOIC AND CENOZOIC GEOGRAPHY OF THE 
‘UNITED STATES 
Juratrias Geography. —In Europe this part of the 
Mesozoic is much better developed and studied than 
in America; but rocks of these ages are found in 
the extreme east and the Far West. The record which 
they have yielded is extremely incomplete and unsatis- 
factory. However, even this fragmentary record is 
sufficient to throw some light upon the conditions of 
the times. 
The general absence of Juratrias rocks seems to 
show that in America, this age was a time of pre- 
vailing land conditions. Had the sea been extensive, 
more deposits should have been left. We know that 
there were mountains in the east, and that to them 
had been added the Appalachian chain, while extensive 
plains stretched from their base at least as far west 
as the Mississippi River. It also seems certain that 
the Canadian area was mainly land. With this in- 
crease in dry land, the climate changed from the 
464 
