On the Age of the Earth

Perry, John

doi:10.1038/051341b0

Cited by 17 publications

(9 citation statements)

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“…A less-than-perfect thermal conductivity for the interior of the Earth would cause it to cool down more slowly than is suggested by Equation 6. Perry and Heaviside modified Kelvin's calculation for the case of large, but finite, interior conductivity (Perry, 1895b;Carslaw and Jaeger, 1959, p. 322) and showed that the Earth's present heat flux is consistent with an age of gigayears, provided that the conducting lid is a few tens of kilometers thick and the effective (or "quasi-") conductivity of the interior is ~100 times greater than that of the lid (Fig. 1B).…”

Section: Kelvin's Assumptionsmentioning

confidence: 99%

“…The suggestion of a fluid mantle was not new; indeed, it was widely understood as the necessary condition for isostasy. Perry published his case (Perry, 1895a(Perry, , 1895b(Perry, , 1895c in the pages of Nature, which, judging by the passion that authors of papers attached to their agendas, was as prominent an organ of scientific discourse in 1895 as it is today. It therefore seems probable that those concerned with the debate about the age of the Earth would have known of Perry's argument.…”

Section: Why Were Perry's Arguments Forgotten and Why Was The Myth Amentioning

confidence: 99%

“…First, experimental evidence showed an increase, if modest, in conductivity of rocks with temperature; in addition, the Earth's increase in density with depth implies a greater proportion of iron and other materials that conduct heat better than do silicates. More radically, he argued (Perry, 1895a) that convection in the fluid, or partly fluid, interior of the Earth would transfer heat much more effectively than would conduction: "… much internal fluidity would practically mean infinite conductivity for our purpose. "…”

Section: Kelvin's Assumptionsmentioning

confidence: 99%

“…A thread running through much of Kelvin's writing on this subject is that the geological community of his time shied away from mathematics (Lindley, 2004). Geologists may have regarded Perry's exchanges with Kelvin (Kelvin, 1895;Perry, 1895aPerry, , 1895bPerry, , 1895c as nothing more than an incomprehensible tussle among physicists. Furthermore, that tussle may have seemed irrelevant.…”

Section: Why Were Perry's Arguments Forgotten and Why Was The Myth Amentioning

confidence: 99%

“…The medium has initial temperature T 0 = 1300 °C, and its surface is maintained at zero temperature (Carslaw and Jaeger, 1959, p. 322). This is the modification to the model illustrated in Figure 1A that was suggested by Perry and Heaviside (Perry, 1895b). (C) The surface heat flux from a semi-infinite medium that is heated internally (Carslaw and Jaeger, 1959, p. 79).…”

Section: Radioactivitymentioning

confidence: 99%

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John Perry's neglected critique of Kelvin's age for the Earth: A missed opportunity in geodynamics

England¹,

Molnár²,

Richter³

2007

Gsa Today

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Many readers know the tale of how William Thomson (later Lord Kelvin) calculated the age of the Earth from physical principles and adhered for over 50 years to an estimate that was far younger than geologists' estimates, despite the virtually unanimous opposition of the geological community of the time. The prevalent version of this tale alleges that the discovery of radioactivity simultaneously provided the demonstration (through radiometric dating) that Kelvin had greatly underestimated the age of the Earth and the explanation of why he was wrong (radioactivity being a source of heat that invalidated Kelvin's calculation). We show this popular story to be incorrect; introducing the known distribution of radioactivity into Kelvin's calculation does not invalidate its conclusion. In 1895, before the discovery of radioactivity, John Perry showed that convection in the Earth's interior would invalidate Kelvin's estimate for the age of the Earth, but Perry's analysis was neglected or forgotten, with the consequence that a powerful argument in favor of mobilism was overlooked during the first few decades of debate about continental drift.

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Section: Kelvin's Assumptionsmentioning

confidence: 99%

Section: Why Were Perry's Arguments Forgotten and Why Was The Myth Amentioning

confidence: 99%

Section: Kelvin's Assumptionsmentioning

confidence: 99%

Section: Why Were Perry's Arguments Forgotten and Why Was The Myth Amentioning

confidence: 99%

Section: Radioactivitymentioning

confidence: 99%

See 3 more Smart Citations