ILLUSTRATIONS 



Restorations of: A. the hypothetical proavian, B. the 



toothed bird Archceopteryx Frontispiece 



I. A. Nebulosity in the Pleiades. B. Spiral nebula in 



Ursa Major facing page 8 



1. Diagram to illustrate tidal forces 14 



2. Origin of a spiral nebula according to Chamberlin 

 and Moulton 18 



II. The western and eastern hemispheres facing page 40 



3. Diagram showing the times and probable extent of the 

 more or less marked climatic changes in the geologic 

 history of North America, and of its elevation into 

 chains of mountains 53 



Figure 4. Glacially striated diabase, made in early Permian 



time. South Africa facing page 54 



Figure 5. Lower Cambrian quartzite, striated in early Permian 



time. South Australia .... facing page 54 



Figure 6. Glacial bowlder beds beneath thick formations of 

 dolomite on the upper Yangtse River, China. Age 

 of till, late Proterozoic .... facing page 56 



Figure 7. Eroded exposure of the oldest known glacial deposits 

 (Lower Huronian), near Cobalt, Ontario 



facing page 56 



Figure 8. Striated bowlder taken from the oldest known glacial 



deposits facing page 56 



Figure 9. Generalized map of North America in Paleozoic time 62 



Figure 10. The marine inundation in Pennsylvanian time . . 66 



Figure 11. Earlier and maximal phases of the Silurian flood . 72 



Figure 12. Great Middle Cretaceous transgression of the oceans 



over the lands 77 



Figure 13. Diagram showing time and extent of the known 

 floods that have inundated North America since the 

 close of the Proterozoic era 79 



