Geoscience Reference
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work (who was known as 'no stop' McGee to friends and 'full stop'
McGee to detractors because he styled himself 'W J McGee'),
announced to a meeting of the American Association for the
Advancement of Science that he estimated, using erosion as a mea-
sure, that the Earth was 15,000 million years old and that 7,000
million years had passed since the beginning of the Cambrian. The
latter figure was remarkably large and quite at variance with others
propounded at the time. The following year he admitted to some
mistakes in his calculations and reduced the figures to 6,000 million
years and 2,400 million years respectively.
Meanwhile across the Atlantic the Liverpudlian architect, civil
engineer and part-time but talented geologist Thomas Mellard Reade
(1832-1909), who incidently was a three-time President of the
Liverpool Geological Society, took up the challenge of Phillips'
method. He had, in his 1877 presidential address to the Society and
in an expanded book version published two years later, discussed the
denudation of soluble geological materials such as limestone, but later
expanded his interests to examine the non-soluble sediments as well.
He was to produce a series of papers in the Geological Magazine and
elsewhere, of which his short contribution entitled 'Measurement of
Geological Time' published just prior to Walcott's in 1893 stated that
the Cambrian began 95,040,000 years ago. This paper was also impor-
tant for his observation that it was difficult to calculate just what a
sedimentary thickness represented chronologically: 'it may be reason-
ably objected that 10 feet of one set of strata may chronologically
represent 1000 feet or more of another.'
Alfred Russel Wallace, in his important book Island Life: Or, the
Phenomena and Causes of Insular Faunas and Floras, Including a
Revision and Attempted Solution of the Problem of Geological
Climates (Macmillan, 1880), wrote that 200 million years was all
that was required for the development of the world's faunas. In
its pages he also entered the sedimentological debate and took
Haughton's cumulative thickness of the stratified rocks of 177,200
feet and remarked that they would have been deposited over a period
