Geological Timescales

Diagram showing five incremental scales of Deep Time, by Chris Rowan, from Highly Allochthonous blog, Do we need a new geological epoch? January 30, 2008

In considering the history of the Earth and of Deep Time, we span not only millions and hundreds of millions of years, but logarithmically different increments of time as well. Hence, in considering the Deep Time Scale, or perhaps it would be better to say, the Deep Time Time Scale, we have to consider several different timescales, at different resolutions.

This brings us to geological time, and the geological timescale is divided into hierarchical units such as epochs, periods, and eras, so the gradations of absolute time can be shown according to five or six scales of resolution, as shown in the above diagram. Featuring increments at the Quaternary (10 and 20 ka, above) and geological (2 ma, 20 ma, etc) they constitute intermediate gradations between large-scale cosmological and historical time. It is on this scale, and especially around the three to five million or so year mark, that the Palaeos review of life on Earth is concerned. MAK110825, 110915

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