Geoscience Reference
In-Depth Information
and within its desmesne had laid out a garden, built laboratories and
stocked a zoological park with many exotic species. There he was able
to observe the habits of his animals at first hand, and also carried out
some experiments on hybridisation.
BUFFON'S DETERMINATION OF THE AGE OF THE EARTH
Ten years before his death he published his important Des e´poques
de la nature, which formed a supplementary part of his Histoire
naturelle, and it was in this volume that he published his dates for
the origin of the Earth. These passages were not his first to deal with
geological ideas: in the very first volume of the series published in 1749
Buffon suggested that a comet had crashed into the Sun and this had
resulted in some solar material being thrown from its surface. This
material separated out into the planets that subsequently revolved
around its parental body. In the essay The´orie de la terre he outlined
his belief that the Earth had a cyclical history that was clearly longer
than that given in the biblical accounts. This caused a considerable
rumpus and theologians in the powerful Sorbonne demanded that he
publish an apology. This he did in subsequent editions, but he did not
withdraw his essay.
In the 1760s he returned to geological ideas that were stimulated
by his thoughts on thermodynamics or simply heat transfer. He began
to explore the idea that the Earth might originally have been molten,
and that it was slowly cooling down. This was not a new idea. Isaac
Newton (1642-1727) had theorised in his Philosophiae naturalis prin-
cipia mathematica published in 1687 that 'a red hot iron equal to
our earth, that is, about 40,000,000 feet in diameter, would scarcely
cool ... in above 50,000 years.' Newton suspected that the rate of
cooling might vary depending on the diameter of the body losing heat,
and hoped that someone might investigate this matter experimen-
tally. Enter Buffon.
If the Earth was cooling down, how long would it take to reach
its present temperature? A clue to how Buffon answered this question
is contained on a map in an 1819 edition of his E
´
poques (Figure
7.2
).
