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The second referred to such topics as the detailed shape of the earth (bulging slightly at the equator) and the dynamics of the earth-moon system.The third referred to the heat of the sun, particularly the rate at which such heat is being lost, compared with the total amount of energy initially available.It was not until 1926, when (under the influence of Arthur Holmes, whose name recurs throughout this story) the National Academy of Sciences adopted the radiometric timescale, that we can regard the controversy as finally resolved.Critical to this resolution were improved methods of dating, which incorporated advances in mass spectrometry, sampling and laser heating.
We, of course, know the final outcome, but we should not let that influence our appreciation of the story as it unfolds.
even the very pyramids.” The 18th century saw the spread of canal building, which led to the discovery of strata correlated over great distances, and James Hutton’s recognition that unconformities between successive layers implied that deposition had been interrupted by enormously long periods of tilt and erosion.
By 1788 Hutton had formulated a theory of cyclic deposition and uplift, with the earth indefinitely old, showing “no vestige of a beginning—no prospect of an end.” Hutton considered the present to be the key to the past, with geologic processes driven by the same forces as those we can see at work today.
Lord Kelvin and his allies used three kinds of argument.
The first of these referred to the rate of heat loss from the earth and the length of time it would have taken to form its solid crust.