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 .
..... Click the link for more information.

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 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 .
..... Click the link for more information.
, see separate articles.
References in periodicals archive ?
Geochemists have long maintained that the proportion of oxygen in the atmosphere has varied on a geologic timescale, but few biologists have considered how such changes would have affected life.
On the geologic timescale, the face of the earth is an animate, expressive entity.
Humans have overwhelmed the natural, slow changes that occur on geologic timescales," Hansen said.
Chondritic meteorites don't have much of the lighter tungsten-182 compared with Earth's mantle, so meteorites mixed into the mantle over geologic timescales could have diluted Earth's younger rocks.
visitors' birthdays and key events in early Grand Canyon explorations) with geologic timescales (e.
However, these smaller-scale effects have the potential to engender new biosignatures that may be preserved over long geologic timescales.
Well, we all know how that story ended: thirty years after Wegener's death, scientists discovered that continents sit on top of a hot, viscous layer of earth that does indeed allow them to move over geologic timescales.