Geoscience Reference
In-Depth Information
andwas handed over by none other than the President for that year, John
Phillips (who himself had been its recipient in 1845). In his address,
Phillips remarked that Darwin had 'never ceased to labour ... in the
cause of geology', and 'through great tracts of America his masterly
hands have sketched and measured the prominent structures of rocks'
and that his work 'has added much to a reputation already raised to the
highest rank.' Unfortunately on account of poor health, Darwin could
not be present to receive the medal in person and Charles Lyell was
given the medal on his behalf. Through his great friend, the recipient
stated that the medal was 'more prized by him as a mark of your
sympathy, because it cheers him in the seclusion in which he finds it
necessary to pursue his studies and researches'.
PROBLEMS WITH PHILLIPS' IDEA
If one returns to Phillips' novel dating methodology one finds that
there was a major difficulty with it: how could one determine
accurately the actual thickness of sediment deposited? Phillips stated
that 72,584 feet of sediment had been deposited since the beginning of
the Cambrian. Of the twenty or so estimates of sediment thickness
that were used to estimate the age of the Earth between 1860 and 1927,
the figure of 12,000 feet of sediment used by James Croll (1821-1890)
in a paper published the year before his deathwas the lowest, while the
highest was 335,800 feet given by William Johnston Sollas
(1849-1936) in 1909, although like some other authors he included
the significant thickness of Precambrian deposits in his calculations
(see Table
10.1
). However, Arthur Holmes in 1927 in his important
book The Age of the Earth: An Introduction to Geological Ideas,
number 102 of Benn's Sixpenny Library, a series that its publishers
proclaimed 'has the revolutionary aim of providing a reference library
to the best modern thought, written by the foremost authorities',
preached caution. He suggested that the total sediment pile was closer
to 529,000 feet in thickness, and noted that 'most of these [earlier]
estimates are little more than rough guesses. We do not know how
much of the story is lost to us, or how much is hidden away.' Holmes
