Geology Reference
In-Depth Information
Extract from a letter to Bob Lawson, dated 14th September, 1911.
Holmes never did take a degree in geology.
of the Earth from an assumed temperature for the Earth, and
instead he would calculate the initial heat of the interior from
an assumed age of the Earth, which he considered to be fairly
well constrained at around 1500 million years. He was clearly
still concerned by Kelvin's arguments that the Earth had not
been cool enough for life to have existed at the surface more
than 20 million years ago, even if the Earth itself was consider-
ably older than that.
While writing of this to Bob he su¬ered another bout of fever
and was too ill to do anything other than think and write a few
lines in his diary:
'Fooled on speculating on origin of Earth.
Have concluded that the inner sphere of high density
[the
Earth's core]
is of different origin to the siliceous acid and
uranium-bearing exterior of much less density.'
Indeed, as we
shall see, this remarkable idea is now exactly how some
scientists do explain the Earth's core.
When the fever passed he continued the letter:
I shall now be able to write my article on the Age of the
