Geoscience Reference
In-Depth Information
The analyses of the returned lunar samples and the advent of supercomputers
led to the ascension of the giant impact model of lunar origin, though even after
forty years we cannot be certain whether it is correct. Perhaps such an ancient and
unique event may always be just beyond our ken.
The calculations of Hulburt, Callendar, and Plass showed that CO
2
absorption
wouldhaveanoticeable effectonglobaltemperature, andcomputermodelingcon-
firmed it. Starting in the late 1970s, temperatures began to rise and kept on rising.
The changing carbon isotopic composition of the atmosphere demonstrate that the
added CO
2
comes from fossil fuel combustion. Thus the data, rather than theory
or modeling results, make anthropogenic global warming a known fact, one about
which virtually all publishing scientists agree.
Uniformitarianism
When a new theory defies conventional wisdom and data are lacking or hard to in-
terpret, scientists are apt to fall back on their tried-and-true principles. In the case
of geology, that meant uniformitarianism. Wegener's proposal was not just another
theory: the idea of colliding continents struck at the heart of the principle that had
made geology a science. As to meteorite impact, could anything be less uniformit-
arian than the sudden arrival of a giant meteorite from out of nowhere?
Schuchert spoke for his profession when he wrote: “We are on safe ground only
so long as we follow the teachings of the law of uniformity in the operation of
nature's laws.” One could argue that continental drift is too slow a process to be
considered catastrophic, or that since drift is happening today, the present is still
the key to the past. But that would be to fiddle with words. On the timescale of our
planet, the collision of continents and the opening of ocean basins surely classifies
as catastrophic. Even more so the impact of an asteroid the size of a mountain ar-
riving at tens of thousands of miles per hour. Meteorite impact not only violated
uniformitarianism, it appealed to a deus ex machina, implicitly accusing geology
of being incapable of solving its own problems using its own methods.
Geology had long ago discarded catastrophism and adopted uniformitarianism
as its ruling paradigm. For twentieth-century geologists, to accept continental drift
and meteorite impact was to turn back the clock and cede geology's most import-
ant principle. As Rollin Chamberlin poignantly said, to accept drift required geo-
logists to “forget everything which has been learned in the last 70 years and start
over again.” And that is essentially what they had to do.
Outsiders
