Divisions of geologic time-major chronostratigraphic and geochronologic units
Revised geologic time scale indicating the ages of the lower bounds of chronostratigraphic and geochronologic units as they are currently known. Modifications to those ages made since the previous time scale was released (2007) are clearly marked.
U.S. Geological Survey Fact Sheet 2010-3059
, Geologic history
, Geologic time periods
, Information system design and development
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