THE GROWTH OF CONTINENTS. 141 
Neither do I see any reason for separating it from 
the others as a distinct age. The plants as well 
as the animals of the two subsequent epochs seem 
to me to show, on the contrary, the same pervad- 
ing character, indicating that the Carboniferous 
epoch makes an integral part of that great divis- 
ion which I have characterized as the Secondary 
age. 
TV itliin the Periods there is a still more limited 
kind of geological division, founded upon the 
special character of local deposits. These I 
would call geological Formations, indicating con- 
crete local deposits, having no cosmic character, 
but circumscribed within comparatively narrow 
areas, as distinguished from the other terms, 
Ages, Epochs, Periods, which have a more uni- 
versal meaning, and are, as it were, cosmopolitan 
in their application. Let me illustrate my mean- 
ing by some formations of the present time. The 
accumulations along the coast of Florida are 
composed chiefly of coral sand, mixed of course 
with the remains of the animals belonging to that 
locality ; those along the coast of the Southern 
States consist principally of loam, which the riv- 
ers bring down from their swamps and low, mud 
dy grounds ; those upon the shores of the Middle 
States are made up of clay from the disintegra- 
tion of the eastern slopes of the Allcghanies ; 
while those farther north, along our own coast, 
