Geology Reference
In-Depth Information
mass westward, could make another go eastward. I believe that we need
to apply elementary physics and mechanics to the continental drift prob-
lem in order to show how impossible drifting would be.
Another particularly vocal opponent was the eminent mathe-
matician and physicist, Harold Je¬reys, who argued that conti-
nental drift was 'out of the question' as no force was adequate
to move continental slabs over the surface of the globe.
Despite having given his first public lecture on continental
drift in 1927, Holmes' seminal paper on the topic was not
published until 1931, just a couple of months before the
Ardnamurchan trip, so inevitably he became the obvious focus
of attention as the beer slipped down and the debate heated up.
Once again Holmes found himself in a minority of one. Attacked
from all sides he was fortunately well versed in holding his
ground when necessary and tried to catch his opponents o¬-
guard by apparently agreeing with them:
'There is of course a very deep rooted prejudice against con-
tinental drift, moreover Wegener's book is rather calculated to
provoke hostile reactions. It is easy to prove Wegener wrong
over and over again, but proving Wegener wrong is by no
means equivalent to disposing of continental drift.'
'So what evidence do you have that it occurred?'
'To my mind the distribution of climates during the Upper
Carboniferous constitutes conclusive proof that continental
drift operated on a very extensive scale. The occurrence of
tillites
[glacial deposits]
of the same geological age in South
America, South and Central Africa, India and Australia pres-
ents us with a hopeless riddle unless we assume that the
glaciated lands were then grouped together near the South
Pole.'
These arguments were di~cult to refute and could not be
explained by land bridges.
'But what about convection currents, where is the evidence for those?'
This was harder to be persuasive about, but data from earth-
quakes was beginning to lend support:
