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.

And the oceans have long since approached something close to a steady state, with chemical sediments removing dissolved minerals as fast as they arrive.

The first argument was completely undermined after taking into account the amount of heat generated by radioactive decay.

The second depended on highly dubious theories of formation of the earth and moon and plays relatively little role in this compilation.

The third act sees the entry of a newly discovered set of physical laws—those governing radioactivity.

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.

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.

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 ...

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.

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