[Chap. LII 



PLANTS OF THE PAST 



GEOLOGIC 



ERAS 



xO 



c 



^ 



p 



(1> 



o^ 



<c? 



^i^ 



^■ 



^ 



# 



.O 



PERIODS 



PLEISTOCENE 



PLIOCENE 



OLIGOCENE 



EOCENE 



CRETACEOUS 



LIFE 



AGE OF MAN 



AGE OF 



FLOWERING 



SEED PLANTS 



AND 



MAMMALS 



<^^^ 





o^ 



c 



i^ 



r.<^ 



<^ 



.&^ 



^ 



PENNSYLVANIAN 



MISSISSIPPIAN 



DEVONIAN 



ORDOVICIAN 



CAMBRIAN 



AGE OF 

 GYMNOSPERMS 



AND 



REPTILES 



MOUNTAIN MAKING 

 EPISODES 



CASCADES AND 

 2nd SIERRA NEVAOAS 

 2rvd UPLIFT OF 

 APPALACHIANS 



HIMALAYAS 



ROCKIES 



1st SIERRA NEVADAS 



1st APPALACHIANS 



AGE OF 



FERNS 



SEED FERNS 



CLUB MOSSES 



AMPHIBIANS 

 FISHES 



FIRST FOSSIL 

 RECORDS 



(glaciation) 



GREAT 



INCREASE OF 



HERBACEOUS 



PLANTS 



8, 



FLOWERING 



PLANTS 



WILLOW, BEECH 



MAGNOLIA 



DIATOMS 



CONIFERS 



CYCADS 





^e 



o^ 



.o 



THALLOPHYTES 



INVERTEBRATES 



GRAND CANYON 

 UPLIFT 



LATER 

 LAURENTIAN 



EARLIER 

 LAURENTIAN 



YEARS AGO 



15,000 

 1.500,000 



30,000,000 

 65,000,000 



(GLACIATION) 



MOSSES AND 

 LIVERWORTS 



FOSSIL FORESTS 



GYMNOSPERMS 

 FERNS 



FUNGI 



SEA WEEDS 



240,000,000 



(glaciation) 



algae and 



bacteria 



700,000,000 



1,000.000,000 



Fig. 359. Diagram showing some of the divisions of geologic time, together 

 with some of the important episodes, and types of plant life. The time scale is 

 based on the disintegration of uranium to helium and lead. 



