Geoscience Reference
In-Depth Information
sion and deposition that they observed and analyzed. One such per-
son was Scotsman James Hutton. A devout man, he believed that
God had created the earth for the express benefit of mankind, and,
since he could see the earth wearing away, became convinced that
some process must restore it. Otherwise the continents would stead-
ily erode into broad, uninhabitable plains—surely not what God had
intended. Hutton sought and found evidence that sediments worn
from the continents and deposited in the sea are subsequently hard-
ened, heated, uplifted, and returned to the continents to start the
process all over again. He viewed earth history as a series of endless
cycles of decay and rejuvenation, with, in his most famous phrase, "no
vestige of a beginning—no prospect of an end." His cycles required
vastly longer periods of time than allowed by a strict interpretation of
the Bible; indeed, they implied an "abyss of time."
It is curious that Hutton has wound up as the "founder of geol-
ogy," for he started with theology rather than with the rocks, drew
conclusions first and then sought evidence for those conclusions, and
propounded a theory of endless cycles that is at best a vast oversim-
plification. Today we would hardly regard these as the mark of a
great scientist. But Hutton has established his place in the pantheon
of geology not for these reasons but because he enunciated a princi-
ple that was to become central to geologic thought and practice:
"Not only are no powers to be employed that are not natural to the
globe, no action to be admitted of except those of which we know
the principle, and no extraordinary events to be alleged in order to
explain a common appearance . . . we are not to make nature act in
violation to that order which we actually observe . . . chaos and con-
fusion are not to be introduced into the order of nature, because cer-
tain things appear to our partial views as being in some disorder.
Nor are we to proceed in feigning causes, when those seem insuffi-
cient which occur in our experience."
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In other words, in explaining the earth, we are to call upon only
those processes that we observe. Given time enough, they will do
the job. This principle was to become the core concept of geology.
Hutton summed up its central premise, in a phrase learned, if not
thoroughly comprehended, by every beginning student of geology
since: "The present is the key to the past." Like most slogans, this one
has a deceptively simple appeal. A moment's thought reveals that
since the time scale of human history is so short compared to deep
time, important processes that act only rarely could have occurred
long ago, but never since, so that there has been no chance for us to
observe them. To the extent that they have not been seen, the present
