66 EVOLUTION OF THE EARTH 



array of modernized animals. The era closes with a very 

 decided glacial climate and another marked change in the 

 animal world, out of which man rises to his present primacy 

 among organisms. Geologists therefore call the present time 

 the Psychozoic era or the Age of Reason. 



POTTSV1LLE 



AREAS OF COAL 



FORMATION DASHED 



FIG. 10. The marine inundation in Pennsylvania!! time. Coal 

 . swamps in partially marine areas indicated by broken lines. 

 From the Pirsson-Schuchert "Text-book of Geology," pub- 

 lished by John Wiley & Sons, Inc. 



