- English geologist
who helped develop interest in the theory of continental drift. He also
pioneered the use of radioactive decay methods for rock dating, giving
the first reliable estimate of the age of the Earth.
Holmes was born in Newcastle-upon-Tyne and studied at Imperial College,
London. He was appointed in 1924 head of the Geology Department at Durham,
moving in 1943 to Edinburgh University.
Holmes was convinced that painstaking analysis of the proportions in
rock samples of elements formed by radioactive decay, combined with
a knowledge of the rates of decay of their parent elements, would yield
an absolute age. From 1913 he used the uranium-lead technique systematically
to date fossils whose relative (stratigraphical) ages were established
but not the absolute age.
In 1928, Holmes proposed that convection currents within the Earth's
mantle, driven by radioactive heat, might furnish the mechanism for
the continental drift theory broached a few years earlier by German
geophysicist Alfred Wegener. In Holmes's view, new rocks were forming
throughout the ocean ridges. Little attention was given to these ideas
until the 1950s.
His books include The Age of the Earth 1913, Petrographic Methods and
Calculations 1921, and Principles of Physical Geology 1944.
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