[from Mary Powers 981023]
Marc Abrams - re the crucial data for Wegener's theory.
In the 1960's new technology enabled the discovery of things like the
sea-floor spreading at the mid-Atlantic Ridge, and the picture emerged of
plates of crust splitting apart as in the Atlantic or the African Rift
Valley, or plunging under other plates (and generating volcanoes)- as is the
case in the Pacific Northwest. Wegener's hypothesis of continental drift
was NOT supported - what was developed was the idea of the movement of
plates of crust, some of which had continental material on them. (What
caught his eye, the fit of South America and Africa, was correct, although
they fit better when the continental shelves rather than shorelines are
taken into account.)
The difference between continental drift/plate tectonics and PCT is this:
Continental drift was a phenomenon with no mechanism to explain it. Plate
tectonics is a more sophisticated version of the phenomenon, and I think
generally accepted now as true, but I'm not sure that there is agreement yet
as to what the mechanism actually is, although there are lots of ideas and
new ones all the time as data is gathered.
PCT is also about a phenomenon, control. However, it is generally not
thought to be either false OR true - it really isn't much thought about at
all, except in the sense of something people do (or try to do) to other
people. So the fact that PCT provides a mechanism to explain control has
not much mattered to most people since it doesn't concern a phenomenon they
feel needs to be explained. If people do start paying attention to control
(which would be nice, since it's the main thing people do), in the same way
that people began to pay attention to continental drift, they will find, as
geologists did not, the basics of the explanation for how it works waiting
for them.
Mary P.