Handbook of Paleontology 439 



the Cascade range of Washington. The old Sierra Ne- 

 vadas had been peneplaned and the growth of the pres- 

 ent ranges begun, and the plateau areas of Utah and 

 Arizona were elevated. Toward the end of Tertiary time 

 (close of Pliocene) the Rocky mountains and Sierra Ne- 

 vadas began a period of growth which has raised them 

 to their present heights, and thereby converted the Great 

 Plains region into a desert through shutting off the moist 

 winds from the Pacific. The Cascade mountains were 

 apparently peneplaned at this time. 



The earliest Tertiary deposits do not occur on Long 

 or Staten Islands but Middle or Late Tertiary deposits 

 are found. Cenozoic deposits in New York State are 

 mainly Quaternary. 



Quaternary Time 



This is the last great period of earth history. Late 

 Tertiary (Pliocene) and early Quaternary was a time 

 of elevation. The continents stood higher than now and 

 there were broad land connections permitting migration 

 of the animals between the continents. Later, elevation 

 ceased and with subsidence these land connections were 

 broken. The cooling of the climate of Tertiary time 

 culminated in the Pleistocene (Greek: most recent) or 

 Glacial Period. Vast ice sheets spread over much of 

 northern North America and Europe. North America 

 was more affected by the glaciation than any other part 

 of the world. In its greatest extent the ice sheet reached 

 as far south as northern New Jersey and Pennsylvania 

 in the east and to the Ohio river in the Mississippi val- 

 ley. Thence the front of the ice sheet stretched north- 

 westward through Missouri, Nebraska and the Dakotas 

 and westward through northern Montana, Idaho and 



