During the 18th century, the most popular theory of how
the current earth came to be was called Neptunist, named after the
god of the seas, Neptune. It was based on the idea that the
continents emerged as the waters that covered all the earth finally
receded. All the matter suspended in those water, eventually
precipitated out, creating the layers of sedimentation that can be
observed world-wide. Of course the question was: what mechanism could
accomplish all of this?
At the end of the 18th century came the Plutonist
theory, named after the god of the volcanic underworld, Pluto. To
James Hutton, called by many the father of modern geology, the earth
is a machine that works to maintain life. New continents arise
because the earth inner heat sources cause expansion, pushing even
the seabeds up to land. Again the question was: what mechanism could
accomplish all of this?
In the 19th century, based on the evidence available
then, many observers of the earth's geological record, such as
Charles Lyell, believed, as Claude Albritton has put it, that "in
order to build a reputable geological science, one must begin by
assuming that the laws of nature are permanent and
immutable--unchanging with the passage of time...and that past
changes had been similar in degree to those operationg in the
Over many years, Lyell's much-revised text Principles of Geology
was incredibly influential and was
read even by the general public. Those who followed his views
came to be called Uniformitarians,
from the word 'uniform.'
Others, such as Georges Cuvier, believed the opposite.
They were called Catastrophists,
from the word 'catastrophe.' They believed that the available
evidence showed that disasterous global events, however rare, had
radically altered the earth's surface a number of different
But in the last forty years the pendulum has gone the
other way. Thanks to original thinking begun by meteorogist Alfred
Wegener, many geoscientists now believe in crustal changes that are:
(1) continuous, (2) gradual and (3) small (that is, relatively local,
not global). They fit in the
Gradualist tradition, which has alway
had common connections with both of the other two positions.
This is the direct opposite of basic pole shift theory,
which emphasizes sudden extremely large changes. Current
consensus beliefs mostly
discount sudden catastrophic change, except in some extreme past,
except for extra-terrestrial causes, such as comets. They don't take
very seriously what we are curious about: that some earth-bound
mechanism--such as polar ice growth--could trigger sudden,
catastrophic dislocation of some or all of the earth's surface.