56 



THE DARWINIAN THEORY 



THE CRUST OF THE EARTH. 



Feet 



• 50 

 . 130 



• 44° 



• 300 

 2,180 



1,360 



2,34° 

 900 



4.75° 



550 

 13,000 

 16,200 

 32,000 

 30,000 

 20,000 



Table of geological strata, with approximate thickness of the 

 several strata in Britain. Total thickness about 235 miles. 



(1) The Tertiary or Kainozoic Period. — The 

 pre-historic cave deposits found in the caves used as 

 dens by wild beasts, who dragged into them the 

 carcases of their prey,, prove the occurrence of the 

 Hycsna, Cave-bear, Rhinoceros, Lion, Reindeer, Bison, 

 Hippopotamtts, and Beaver — with man. These forms 

 are now living, but not in England. In the Glacial 

 period the earlier deposits show some of these 

 disappearing, others persisting, and animals appearing 

 that now do not exist anywhere — viz., the Mam- 

 moth, Woolly Rhinoceros, the Sabre-toothed Tiger 

 and the Irish Elk or deer. In the Pliocene period 

 we find evidence of the Mastodon and Tapir ; and in 

 the Eocene period, of the Didelphys, Opossum, and 

 Hyracotherium. 



(2) The Secondary or Mesozoic Period. — The 

 entire group found at this period is extinct. The 



