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USGS · 70039222

Geologic time: The age of the Earth

William L. Newman
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Abstract

The Earth is very old 4 1/2 billion years or more according to recent estimates. This vast span of time, called geologic time by earth scientists and believed by some to reach back to the birth of the Solar System, is difficult if not impossible to comprehend in the familiar time units of months and years, or even centuries. How then do scientists reckon geologic time, and why do they believe the Earth is so old? A great part of the secret of the Earth's age is locked up in its rocks, and man's centuries-old search for the key led to the beginning and nourished the growth of geologic science.

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William L. Newman. 1977. Geologic time: The age of the Earth. https://doi.org/10.3133/70039222

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