|Ageing the Earth|
This broadcast describes the four great Eons of history: the Hadean, the Archean, the Proterozoic and the Phanerozoic. Together, they encompass four and a half billion years. How can we begin to make sense of such a huge swathe of time? And can we be sure that we have got the age of the Earth right? Geologists use Eras, Periods and Epochs to further punctuate what is known as Deep Time, but can we be sure that the classifications we use do not obscure more than they reveal? This radio broadcast explores these questions, and explains that we are living in the Cenozoic era and Holocene epoch; that there are gaps in the rock record that must be pieced together; how much time is involved during the mass extinctions of the past, particularly as revealed at Bottaccione Gorge in Italy where the duration of the K-T boundary was measured; that the Cambrian explosion marks the time when life finally acquired hard parts and shells; and how radioactive decay of carbon and uranium isotopes are used to date rocks. The broadcast is 45 minutes in length.
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DLESE Catalog ID: DLESE-000-000-007-807
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Publisher: BBC Radio 4
Editor: Melvyn Bragg
BBC Radio 4, In Our TIme Radio Series