has produced
volcanic cataclysms, upheaving ocean-beds to form continents. The rugged
and uneven surfaces of mountains, the tilted and broken character
of stratified rocks everywhere, are the standing witnesses of these
gigantic upheavals.

And with this the imagined cycle is complete. The continents, worn away
and carried to the sea by the action of the elements, have been made
over into rocks again in the ocean-beds, and then raised once more into
continents. And this massive cycle, In Hutton's scheme, is supposed
to have occurred not once only, but over and over again, times without
number. In this unique view ours is indeed a world without beginning
and without end; its continents have been making and unmaking in endless
series since time began.

Hutton formulated his hypothesis while yet a young man, not long after
the middle of the century. He first gave it publicity in 1781, in a
paper before the Royal Society of Edinburgh:

"A solid body of land could not have answered the purpose of a habitable
world," said Hutton, "for a soil is necessary to the growth of plants,
and a soil is nothing but the material collected from the destruction of
the solid land. Therefore the surface of this land inhabited by man, and
covered by plants and animals, is made by nature to decay, in dissolving
from that hard and compact state in which it is found; and this soil
is necessarily washed away by the continual circulation of the water
running from the summits of the mountains towards the general receptacle
of that fluid.

"The heights of our land are thus levelled with our shores, our fertile
plains are formed from the ruins of the mountains; and those travelling
materials are still pursued by the moving water, and propelled along the
inclined surface of the earth. These movable materials, delivered into
the sea, cannot, for a long continuance, rest upon the shore, for by the
agitation of the winds, the tides, and the currents every movable thing
is carried farther and farther along the shelving bottom of the sea,
towards the unfathomable regions of the ocean.

"If the vegetable soil is thus constantly removed from the surface of
the land, and if its place is then to be supplied from the dissolution
of the solid earth as here represented, we may perceive an end to this
beautiful machine; an end arising from no error in its constitution as
a world, but from that destructibility of its land which is so necessary
in the system