Geology Reference
In-Depth Information
And the ringing, final line of the 1788 treatise:
If the succession of worlds is established in the system of nature, it is in vain
to look for anything higher in the origin of the earth. The result, therefore, of
our present enquiry is, that we find no vestige of a beginning,—no prospect
of an end. (304)
The role of deep time within the mechanics of Hutton's theory has been
discussed ably and often, and I shall give only the briefest outline here: By
recognizing the igneous character of many rocks previously viewed as
sediments (products of decay), Hutton incorporated a concept of repair into
geological history. If uplift can restore an eroded topography, then geological
processes set no limit upon time. Decay by waves and rivers can be reversed,
and land restored to its original height by forces of elevation. Uplift may
follow erosion in an unlimited cycle of making and breaking.
Hutton describes the earth as a machine—a device of a particular kind. Some
machines wear out as their parts fall into irreversible disrepair. But Hutton's
world machine worked in a particular way that prevented any aging.
Something had to initiate the system (an issue beyond the bounds of science,
in Hutton's view), but once kicked into action, the machine could never stop
of its own accord, because each stage in its cycle directly caused the next. As
Playfair wrote: "The Author of nature has not given laws to the universe,
which like the institutions of men, carry in themselves the elements of their
own destruction. He has not permitted, in his works, any symptom of infancy
or of old age, any sign by which we may estimate either their future or their
past duration" (1802, 119).
Hutton's self-renewing world machine works on an endlessly repeating, three-
stage cycle. First, the earth's topography decays as rivers and waves
disaggregate rocks, forming soils on the continents and washing the products
of erosion into the oceans. Second, the comminuted bits of old continents are
deposited as horizontal strata in the ocean basins. As the strata build up, their
own weight generates sufficient heat and pressure to mobilize the lower
layers. Third, the heat of melting sediments and intruding magmas causes
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