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Early Theories and Estimates of the Earth's Age, Lecture notes of Earth Sciences

Early attempts to estimate the age of the Earth, from Archbishop Ussher's calculation of 5,658 years in 1404 BC, to Herodotus' several thousand years, George du Buffon's collision theory, John Joly's determination based on salt accumulation, and Lord Kelvin's thermal calculations. The document also discusses the controversy between scientific and religious communities regarding an 'old Earth'.

What you will learn

  • How did Lord Kelvin estimate the age of the Earth using thermal calculations?
  • How did Archbishop Ussher calculate the age of the Earth?
  • What was George du Buffon's theory on the origin of the Earth?

Typology: Lecture notes

2021/2022

Uploaded on 09/27/2022

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Early attempts to date the age
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Early attempts to date the age

of the Earth

Archbishop Ussher - 1654 Added up all the generations after Adam, and came up with an age of the Earth as 5,658 years old, having formed in 4004 B.C on October 12rd at 9 am. Herodotus - Greek historian, dated the age of the Earth using the rate of growth he observed in the Nile Delta; Earth was several thousand years old.

Lord Kelvin 1846- Quantified Buffon’s early ideas of an originally molten Earth which cooled to its present state as a result of the dissipation of heat over time. a. Rocks melt at ~3,900°C b. Assumed a geothermal gradient of ~0.56ºC/50 feet depth c. Derived mathematical estimates for thermal conductivity So that….at a depth of 50-100 miles the interior would still be molten (where magma was derived). He then determined that the geothermal gradient would have changed over time, so that at one point the surface itself would have been molten…at one point it was ~1º/foot!!) Result: age of Earth 20-400 million years old; later revised to 24-30 Ma Problems with his analysis???

An “old Earth” was incorporated into conceptions about how the Earth “worked” by scientists of the late 1800’s, including Darwin. This was, however NOT what the religious community and prevailing public opinion believed. Biologist T.H. Huxley Bishop of Oxford Samuel Wilberforce Darwin in 1859