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himself acknowledged that it caused him trouble. If we believe
Archibald Geikie, his influence on the biologists who adhered to the
longer time frame required by natural selection would appear to have
been slight. In fact many biologists did not require the longer timescale
suggested by Darwin, as they did not accept natural selection. They
preferred the Lamarckian means of biological change which required
little time. Natural selection and thus the need for greater time was
generally accepted by most biologists by the 1930s. In his presidential
address to the geological community at the British Association for the
Advancement of Science meeting held in Dover in 1899, Geikie firstly
acknowledged the debt geologists owed Thomson:
Geologists have been led by his criticisms to revise their
chronology. They gratefully acknowledge that to him they owe
the introduction of important new lines of investigation, which
link the solutions of the problems of geology with those of physics
but then he delivered a sharp reprimand to the ennobled physicist and
a reminder of the leanings of palaeontologists towards a chronology
longer than the one that he proposed:
It is difficult satisfactorily to carry on a discussion in which your
opponent entirely ignores your arguments, while you have given the
fullest attention to his. [Geologists] have been willing to accept Lord
Kelvin's original estimate of 100millions of years as the periodwithin
which the history of life upon the planet must be comprised ... yet
there is undoubtedly a prevalent misgiving, whether in thus seeking
to reconcile their requirements with the demands of the physicist
they are not tying themselves down within the limits of time which
on any theory of evolution would have been insufficient for the
development of the animal and vegetable kingdoms.
Thanks to his continual tinkering with his age determinations
Thomson more than likely reduced the credibility of his work, and
his research in the area of geochronology was, like that of John Joly
and his oceanic salination scheme, overtaken by the emergence of
