THE GROWTH OF CONTINENTS. 
139 
vanished, and which may contain those interme- 
diate links for which we vainly seek. But here 
there is no such gap in the evidence. In the very 
same sheets of water, covering limited areas, we 
have the successive series of deposits containing 
the remains of animals which continue perfectly 
unchanged during long intervals. Immediately 
upon these, and accompanied by a more or less 
violent shifting of the surface,* traceable by the 
consequent discordance of the strata, is intro- 
duced an entirely new set of animals, differing 
as much from those immediately preceding them 
as do those of the present period from the older 
animals, (our predecessors, but not our ances- 
tors,) traced by Cuvier in the Tertiary deposits 
underlying those of our own geological age. I 
subjoin here a tabular view giving the Epochs in 
their relation to the Ages, and indicating, at 
least approximately, the number of Periods con- 
tained in each Epoch. 
Age of Man 
1 :rtiary Age : 
Age of Mammalia 
Secondary Age : 
Age of Reptiles 
Palajozoic or Primary Age : 
Age of Fishes 
* I use surface often in its geological significance, meaning 
earth-crust, and applied to sea-bottom as well as to dry land. 
Present Epoch. 
' Pliocene 
. Miocene 
► with at least twelve Periods. 
Eocene 
' Cretaceous 
Jurassic i 
Triassic 
■ with about twenty Periods. 
Permian 
. with eight or nine Periods. 
Carboniferous 
i Devonian 
r Silurian 1 
, with ten or twelve Periods. 
