ow them. What then? Why, as the continents wear
down, the oceans are filling up. Along their bottoms the detritus of
wasted continents is deposited in strata, together with the bodies of
marine animals and vegetables. Why might not this debris solidify to
form layers of rocks--the basis of new continents? Why not, indeed?

But have we any proof that such formation of rocks in an ocean-bed has,
in fact, occurred? To be sure we have. It is furnished by every bed
of limestone, every outcropping fragment of fossil-bearing rock, every
stratified cliff. How else than through such formation in an ocean-bed
came these rocks to be stratified? How else came they to contain the
shells of once living organisms imbedded in their depths? The ancients,
finding fossil shells imbedded in the rocks, explained them as mere
freaks of "nature and the stars." Less superstitious generations had
repudiated this explanation, but had failed to give a tenable solution
of the mystery. To Hutton it is a mystery no longer. To him it seems
clear that the basis of the present continents was laid in ancient
sea-beds, formed of the detritus of continents yet more ancient.

But two links are still wanting to complete the chain of Hutton's
hypothesis. Through what agency has the ooze of the ocean-bed been
transformed into solid rock? and through what agency has this rock been
lifted above the surface of the water to form new continents? Hutton
looks about him for a clew, and soon he finds it. Everywhere about us
there are outcropping rocks that are not stratified, but which give
evidence to the observant eye of having once been in a molten state.
Different minerals are mixed together; pebbles are scattered through
masses of rock like plums in a pudding; irregular crevices in otherwise
solid masses of rock--so-called veinings--are seen to be filled with
equally solid granite of a different variety, which can have gotten
there in no conceivable way, so Hutton thinks, but by running in while
molten, as liquid metal is run into the moulds of the founder. Even
the stratified rocks, though they seemingly have not been melted, give
evidence in some instances of having been subjected to the action of
heat. Marble, for example, is clearly nothing but calcined limestone.

With such evidence before him, Hutton is at no loss to complete his
hypothesis. The agency which has solidified the ocean-beds, he says,
is subterranean heat. The same agency, acting excessively,