AN INTRODUCTION TO THE STUDY OF FOSSILS 407 



GEOLOGIC TIME SCALE 



Era 



Cenozoic 



Mesozoic 



Paleozoic 



Period 



Holocene 



(Recent, or the present) 

 Pleistocene 



(Glacial) 

 Pliocene 

 Miocene 

 Oligocene 

 Eocene 

 Cretaceous 



(Upper Cretaceous) 

 Comanchean 



(Lower Cretaceous) 

 Jurassic 

 Triassic 

 Permian 

 Pennsylvanian 



(Upper Carboniferous) 

 Mississippian 



(Lower Carboniferous) 

 Devonian 

 Silurian 

 Ordovician 

 . Cambrian 

 Pre-Cambrian 



(Many Geologists use the 

 Period Names as Follows) 



Holocenic 



Pleistocenic 



Pliocenic 



Miocenic 



Oligocenic 



Eocenic 



Cretacic 



Comanchic 



Jurassic 

 Triassic 

 Permic 

 Pennsylvania 



Mississippic 



Devonic 

 Siluric 

 Ordovicic 

 Cambric 

 Pre-Cambric 



