Geology Reference
In-Depth Information
Like everyone else in the Cavendish at that time Strutt had
been swept along with the rising tide of interest in radio-
activity, and had been working on it when he became embroiled
in the famous '
Times
debate' with Kelvin. A year after the debate
Lord Kelvin died, but he left behind him a legacy that the Earth
was only twenty 20 million years old, which hung like a mill-
stone around the necks of geologists, for the majority needed
far greater amounts of time in which to shape the Earth.
Strutt felt it was time to dispose of the millstone and was now
working on the idea of using radioactivity to date the age of the
Earth.
But how had it come about, this twenty million years?
In 1862 Lord Kelvin was the Professor in Natural Philosophy at
Glasgow University and the world's expert on thermodynamics.
A scientist of international repute and ferocious ability, he was
then at the height of his powers and widely regarded by his con-
temporaries as the greatest physicist of his day - a formidable
opponent. In April of that year he opened his address to a meet-
ing of the Edinburgh Royal Society with a blistering attack on
geologists and their methods: 'For eighteen years it has pressed
on my mind, that essential principles of Thermo-dynamics have
been overlooked by geologists'. He went on to berate them for
their insistence that the natural processes seen acting on the
Earth today were the same as those in the geological past, and
that therefore the rates of those processes had never changed
over geological time. He condemned the geologists' unscientific
demands for unlimited time and considered that the Earth had
a very definite beginning and would also have a very conclusive
end.
Kelvin argued that wherever you looked in the world, mines
and boreholes showed that temperatures within the Earth
increased with depth. From this he deduced that the Earth was
