CONTENTS 19 



PAGE 



Invertebrates . 626 



Insects. Horseflies, Tsetse Flies, and Ants. 



Vegetation 630 



Grasses. Dzemonhelix. Geological History of Sequoias. Diatoms. Ex- 

 ceptional Preservation of Plants. Plant Localities in North America. 



Climate 634 



Difficulty in Determining Tertiary Climates. Eocene. Oligocene. Mio- 

 cene. Pliocene. 



Effects of Isolation and Migration . . 636 



Eocene Invasion. Oligocene Invasion. Miocene African Invasion. Plio- 

 cene South American Invasion and Intermigration between the Old and 

 New Worlds. Duration of the Tertiary. 



CHAPTER XXII 



QUATERNARY 

 Changes at the Close of the Tertiary . . . „ .... 643 



Elevation. Glaciation. Changes in Life. 



Distribution of the Ice Sheets 645 



Other Continents. North America. 



Development of the Ice Sheets 647 



Thickness of Ice Sheets at Center. 



Glacial and Interglacial Stages . 648 



Characteristics of Former Drift Sheets. 



History of the Great Lakes 651 



Preglacial Drainage. Origin of the Basins. Great Lakes Stages. The 

 Champlain Subsidence. 



Other Pleistocene Lakes 656 



Lake Agassiz. Lake Bascom. Great Basin Lakes. 



Loess . 657 



Duration 658 



Causes of Glaciation 660 



Elevation. Astronomical. Atmospheric Hypothesis. 



Effects of Glaciation 662 



Life of the Pleistocene 663 



Interglacial Deposits. North and South Migrations during Glacial and 

 Interglacial Times. Deposits beyond the Ice Sheets or Protected from 

 Them. Deposits on the Last Drift. Vegetation. Mammoths and 

 Mastodons. Edentates. Pleistocene Carnivores. Horses, Camels, 

 etc. Birds. 



Prehistoric Man 674 



Eolithic. Paleolithic Man. Neolithic Man. Man in North America. 

 Birthplace of Man. Effect of the Advent of Man. 

 Future Habitability of the Earth 683 



APPENDIX 

 Common Minerals , <,„,., „ < 685 



