geologic timescale
See also: Geologic Timescale (table)Geologic Timescale
Era Period Epoch Approximate duration
(millions of years)
Approximate number of years ago
(millions of years)
Cenozoic Quaternary Holocene 10,000 years ago to the present
Pleistocene 2 .
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geologic timescale,
a chronological scale of earth's history used to measure the relative or absolute age of any part of geologic time. Of the numerous timescales, the most common is based on geologic time units, which divide time into eras, periods, and epochs. Each division is based on a specific set of geological or paleontological conditions that make it different from the other divisions, such as varying rock type or fossils within the strata. The largest unit is the eon; eons are subdivided into eras; eras into periods; and some, usually more recent periods, into epochs. In some timescales, epochs are further divided into ages. Each geologic time chart varies, depending on the latest findings dating rocks and fossils of that particular age, or on the country where the chart originated. For each unit and its subdivisions, which are listed in the table entitled Geologic TimescaleGeologic TimescaleEra Period Epoch Approximate duration
(millions of years)
Approximate number of years ago
(millions of years)
Cenozoic Quaternary Holocene 10,000 years ago to the present
Pleistocene 2 .
..... Click the link for more information. , see separate articles.