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Radiometric dating not accurate

They assumed that current rates—of sediment deposition and of salt transport by rivers—were the same as historical rates, despite the evidence they had that our own age is one of atypically high geologic activity. The rock cycle, as we now know, is driven by plate tectonics, with sedimentary material vanishing into subduction zones.

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Having come that far, they were initially quite reluctant to accept a further expansion of the geologic timescale by a factor of 10 or more.One referred to the depth of the sediments and the time they would have taken to accumulate; the other referred to the salinity of the oceans, compared with the rate at which rivers are supplying them with sodium salts.In hindsight, both theories were deeply misguided, for similar reasons.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.This position came to be known as uniformitarianism, but within it we must distinguish between uniformity of natural law (which nearly all of us would accept) and the increasingly questionable assumptions of uniformity of process, uniformity of rate and uniformity of outcome.

That is the background to the intellectual drama being played out in this series of papers.

He inferred that where the layers are not horizontal, they must have been tilted since their deposition and noted that different strata contain different kinds of fossil.

Robert Hooke, not long after, suggested that the fossil record would form the basis for a chronology that would “far antedate ...

His achievements ran from helping formulate the laws of thermodynamics to advising on the first transatlantic telegraph cable. Shelton was a philosopher of science, critical (as shown in his contribution, the 1915 article “Sea-Salt and Geologic Time”) of loose thinking and a defender of evolution in debates.

Harlow Shapley, who wrote an article in 1919 on the subject, was an astronomer, responsible for the detection of the redshift in distant nebulae and hence, indirectly, for our present concept of an expanding universe. Russell, author of the 1921 article on radioactive dating, was familiar to me for his part in developing the Hetzsprung-Russell diagram for stars, but I was surprised to discover that he was also the Russell of Russell-Saunders coupling, important in atomic structure theory. The prologue to the drama is the mid-19th century recognition of the relation between heat and other kinds of energy (see the 1857 article “Source of the Sun’s Heat”).

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.