Geoscience Reference
In-Depth Information
took the figures given by earlier workers and came up with eight
different results that ranged from 80 million to 350 million years,
a variation of 270 million. Rightly, he recognised that parts of the
Phanerozoic sedimentary record might have been eroded away, but
precisely how much sediment had been lost was difficult to deter-
mine. If an unconformity is recognised in the field, such as those seen
by James Hutton in Scotland, it is not always obvious what this
sedimentary interregnum represents in terms of time and lithology.
LATER ESTIMATES OF TIME DERIVED FROM
THE SEDIMENTARY PILE
Further hour-glass calculations using Phillips' method followed. In
1868 Archibald Geikie (1835-1924), the then Director of the
Geological Survey of Scotland, published an account of present-day
denudation rates. He pointed out that given the rate of reduction of the
present land surface by 1 foot in every 6,000 years, Europe would
disappear in four million years, North America in four and a half
million years, and both Asia and Africa in seven million years. He
recognised that physicists had expressed some difficulties with the age
of the Earth as it had been calculated by their scientific colleagues the
geologists, and warned that the estimates made by the latter might
have to be reduced, contrary to geological evidence. Perhaps the most
celebrated work in this area (on account of the huge fluctuations of his
time determinations) was that by the Dublin geological professor the
Reverend Samuel Haughton (1821-1897) who, like John Phillips, was
a supporter of William Thomson and an opponent of Charles Darwin.
Haughton had interests in many fields: geology, mathematics, animal
physiology, medicine and education. Born to Quaker parents, he was
brought up anAnglican and educated at Trinity College Dublin, where
he became a Fellow at the remarkably tender age of twenty-four.
Almost immediately he was ordained, and was appointed to the
Chair of Geology in 1851, the chair filled by Phillips eight years earlier.
During his tenure he also studied medicine at the College during
which time he developed his keen interest in animal physiology.
