Geology Reference
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in place of Holmes, again tried to lay the spectre of Kelvin who
still rose to haunt the assembly, and again put forward the
arguments in favour of radiometric methods. William Sollas,
Professor of Geology at Oxford, seemed overwhelmed at the
amount of time now available to geologists after the paucity
o¬ered by Kelvin: 'the geologist who had before been bankrupt
in time now found himself suddenly transformed into a capi-
talist with more millions in the bank than he knew how to dis-
pose of ', but, perhaps understandably, he still urged caution
and heeded geologists to substantiate the time being o¬ered by
the physicists 'before committing themselves to the reconstruc-
tion of their science'. But the die-hards were slowly growing
smaller in their numbers and the meeting ended with a gener-
al acceptance that the age of the Earth was around 1500 million
years.
The following year, in 1922, a similar meeting was held in
America, sponsored by the American Philosophical Society, with
speakers who spoke from the view point of a geologist, a
palaeontologist, an astronomer and a physicist. The problems
discussed and the conclusions reached were much the same as
their British colleagues, but in particular the geologist, Thomas
Chamberlin, took his colleagues to task for adhering to an age
of 100 million years. The butt of his comments were specifically
directed at John Joly and his refusal to renounce his ideas on an
age of the Earth based on salinity in the oceans. So, although
little new work had been done on age dating while Holmes was
away, the tide of opinion was gradually turning and on return-
ing to academic life in 1924 after a four year absence he noted
'there is now a marked change in opinion in favour of the
longer estimates' .
Finally, twenty years after Rutherford had dated the first
mineral by radioactivity and twenty-five years since Kelvin's
last publication advocating a 20 million year old Earth, there
seemed to be a general acceptance that ages measured by
radioactive methods were at least of the right order of magni-
 
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