306° GEOLOGICAL EVIDENCES 
single age, was destined marvellously to unlock the past history 
of our planet, and to acquaint us with God’s doings upon it, as 
the Creator of all, for myriads of ages ere he had first breathed 
the spirit of life into human nostrils, or man had become a 
living soul? It is one of the great marvels of our day, that 
through the key furnished by geologic science we can now 
peruse the history of past creations more clearly, and arrive at 
a more thorough and certain knowledge of at least the struct- 
ural peculiarities of their organisms, than we can read the 
early histories of the old dynasties of our own species, that 
flourished and decayed on the banks of the Euphrates or of 
the Nile, or ascertain the true character of the half-forgotten 
tyrants with whom they terminated, or from whom they began. 
It seems scarce possible that, in at least the leading facts 
of geologic history, we shall witness any very considerable 
change. There is no truth more thoroughly ascertained than 
that the great Tertiary, Secondary, and Paleozoic divisions 
represent in the history of the globe, periods as definitely dis- 
tinct and separate from each other as the modern from the 
ancient history of Europe, or the events which took place pre- 
vious to the Christian era from those that date in the subsequent 
centuries which we reckon from it. All over the globe, too, in 
the great Paleozoic division, the Carboniferous system is found 
to overlie the system of the Old Red Sandstone, and that, in 
turn, the widely developed Silurian system. It is not less cer- 
tain, that in the Secondary division, the Triassic deposits are 
overlaid by the Oolitic ones, and both by the Cretaceous ; nor 
yet, that in the Tertiary division, the beds of the Pliocene, with 
their large per centages of existing shells, as exemplified in 
the Red and Coraline Crags, belong to a greatly later period 
than that old Eocene age represented by the extinct shells and 
strange mammals of the Paris basin and the London clay. 
There is no human history more definitely ranged into centu- 
