Geology Reference
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exorbitant ten shillings each. Feeling very grown up, they talked
of the adventures that lay ahead of him as they dined at the
Popular restaurant and taxied to Finsbury Park, just in time to
catch the last train to Palmers Green where he stayed the night.
Edie saw him o¬ at Palmers Green station early next morning
and promised to write.
In between all this Holmes somehow found time to finish the
work in his laboratory. He wrote up the results whilst in
Gateshead and, on the morning of his departure for Africa, he
left them with Professor Strutt. It had taken months of hard work
to complete, but finally it was all worth it. The rock from Norway
had previously been assigned a Devonian geological age, thus
Holmes revealed the Devonian to be at least 370 million years
old, and in doing so he determined the first ever uranium-lead
age. It was a truly thrilling moment; his own wild miracle.
In addition to his own 'age' determination Holmes had also
re-calculated some age data published by Boltwood, in line with
more recent procedures, and had assigned a geological period
to each of those ages, something which Boltwood had 'unfor-
tunately omitted to do' . Boltwood was already well established
in radioactivity circles, and it is unclear how he responded to
this young upstart recalculating his data and ticking him o¬ in
print for not having ascribed a geological period to the results,
but Boltwood was a chemist and not really interested in the geo-
logical aspects of his work. Holmes on the other hand, realised
that there was no point in having an age for its own sake. To
him the only thing that mattered was that each radiometric
'date' was a new point in geological time, so it had to be matched
to a geological 'age'.
In fact Holmes' single age determination fitted perfectly with
Boltwood's revised results, and Holmes laid out the radiomet-
ric ages alongside their respective geological ages so all could
see that as the rocks became older geologically, so too did their
radiometric dates. By doing this he was hoping to instil
confidence in the radiometric methods, which were still treated
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