646 The Harmony of Creation. 
globe, as it is now presented, is essential to the present 
condition of organic life. Were the oceans considerably 
smaller than they now are, or were Asia and America con- 
centrated within the tropics, the tides, the oceanic currents, 
and the meteorological phenomena on which the existence 
of the vegetable and animal kingdom depend, would be so 
greatly altered that it is a question whether man could 
have lived, but he certainly could never have attained to 
his present degree of civilisation. Progression would not 
then have marked in the especial manner which it now does 
man’s destiny on earth. 
In the past ages of the earth’s history immense oceans 
covered the greater part of the globe. If no convulsion 
had taken place the earth would have continued in this 
state. It would have been one universal ocean undivided 
by land. It follows, therefore, that before terrestrial tribes 
were created on the globe it must have been the subject 
of volcanic action, of various catastrophes, in order that 
the land should be raised above the surface of the waters. 
Geological research proves that these changes were not 
effected suddenly nor permanently at one particular time, 
but that a long succession of upheavings and of oscillations 
of the earth’s crust took place through a long succession of 
ages, during the course of which the outlines of land and 
water were frequently varied. The land of one age became 
the bottom of an ocean in another age and the ocean bed 
the dry land. 
For a long period during which these catastrophes were 
developed at intervals, the superficial temperature depended 
incalculably more upon the internal heat transmitted to 
the surface through the earth’s crust than upon the effects 
of solar radiation. The temperature received from the 
interior of the earth would be equally diffused to every 
part of the earth. The immense oceans would also con- 
tribute to distribute the heat equally to every region. 
Therefore, during the early part of the earth’s history, the 
superficial temperature was uniform at all latitudes. 
The great uniformity of climate which then reigned over 
the globe, caused at the same time a wonderful uniformity 
of vegetation in its various zones. In the eastern as in 
the western hemisphere, between the tropics and beyond 
the Arctic circle, wherever coal has been deposited, the 
naturalist meets with the same forms, often even with the 
same species of plant. 
The space of time requisite to form the vast coal fields” 
