Professor Agassiz considers that the very fact of certain stratified
rocks, even among the oldest formations, being almost entirely made
up of fragments of organised beings, should long ago have satisfied
the most sceptical that both _animal and vegetable life were as active
and profusely scattered upon the whole globe at all times, and during
all geological periods, as they are now_. No coral reef in the Pacific
contains a larger amount of organic _débris_ than some of the limestone
deposits of the tertiary, of the cretaceous, or of the oolitic, nay
even of the paleozoic period; and the whole vegetable carpet covering
the present surface of the globe, even if we were to consider only
the luxuriant vegetation of the tropics, leaving entirely out of
consideration the entire expanse of the ocean, as well as those tracts
of land where, under less favourable circumstances, the growth of
plants is more reduced,--would not form one single seam of workable
coal to be compared to the many thick beds contained in the rocks of
the carboniferous period alone.