lobe, equally powerful in
building it up. Fire and water wrought together in this work, if not
always harmoniously, at least with equal force and persistency. I have
said that there was a time when no atmosphere surrounded the earth;
but one of the first results of the cooling of its crust must have
been the formation of an atmosphere, with all the phenomena connected
with it,--the rising of vapors, their condensation into clouds, the
falling of rains, the gathering of waters upon its surface. Water is a
very active agent of destruction, but it works over again the
materials it pulls down or wears away, and builds them up anew in
other forms. As soon as an ocean washed over the consolidated crust of
the globe, it would begin to abrade the surfaces upon which it moved,
gradually loosening and detaching materials, to deposit them again as
sand or mud or pebbles at its bottom in successive layers, one above
another. Thus, in analyzing the crust of the globe, we find at once
two kinds of rocks, the respective work of fire and water: the first
poured out from the furnaces within, and cooling, as one may see any
mass of metal cool that is poured out from a smelting-furnace to-day,
in solid crystalline masses, without any division into separate layers
or leaves; and the latter in successive beds, one over another, the
heavier materials below, the lighter above, or sometimes in alternate
layers, as special causes may have determined successive deposits of
lighter or heavier materials at some given spot.

There were many well-fought battles between geologists before it was
understood that these two elements had been equally active in building
up the crust of the earth. The ground was hotly contested by the
disciples of the two geological schools, one of which held that the
solid envelope of the earth was exclusively due to the influence of
fire, while the other insisted that it had been accumulated wholly
under the agency of water. This difference of opinion grew up very
naturally; for the great leaders of the two schools lived in different
localities, and pursued their investigations over regions where the
geological phenomena were of an entirely opposite character,--the one
exhibiting the effect of volcanic eruptions, the other that of
stratified deposits. It was the old story of the two knights on
opposite sides of the shield, one swearing that it was made of gold,
the other that it was made of silver; and almost killing each