Dating on the earth
Even less should we let that knowledge influence our judgment of the players, acting as they did in their own time, constrained by the concepts and data then available.
One outstanding feature of this drama is the role played by those who themselves were not, or not exclusively, geologists.
Roman poet Lucretius, intellectual heir to the Greek atomists, believed its formation must have been relatively recent, given that there were no records going back beyond the Trojan War.
The Talmudic rabbis, Martin Luther and others used the biblical account to extrapolate back from known history and came up with rather similar estimates for when the earth came into being.
Radioactivity offered not only a resolution to the puzzle of the earth’s energy supply but also a chronology independent of questionable geologic assumptions and a depth of time more than adequate for the processes of evolution.
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 ...
And we should resist the temptation to blame them for their resistance. Different methods of measurement (such as the decay of uranium to helium versus its decay to lead) sometimes gave discordant values, and almost a decade passed between the first use of radiometric dating and the discovery of isotopes, let alone the working out of the three separate major decay chains in nature.
The constancy of radioactive decay rates was regarded as an independent and questionable assumption because it was not known—and could not be known until the development of modern quantum mechanics—that these rates were fixed by the fundamental constants of physics.
Nevertheless, by the late 19th century the geologists included here had reached a consensus for the age of the earth of around 100 million years.