What are the units of the geologic time scale?

What are the units of the geologic time scale?

The main units of the geologic time scale, from largest (longest) to smallest, are: eon, era, period, epoch and age. Each corresponds to the time in which a particular layer of rock was formed. Rocks have been forming, layer upon layer, since the earliest days of Earth.

Is the geologic time scale a dynamic resource?

New Time Scale. Therefore, Divisions of Geologic Time (fig. 1) is intended to be a dynamic resource that will be modified to include accepted changes of unit names and boundary age estimates. This fact sheet is a modification of USGS Fact Sheet 2007-3015 by the U.S. Geological Survey Geologic Names Committee (2007).

When did John Phillips create the geologic time scale?

British geologists were also responsible for the grouping of periods into eras and the subdivision of the Tertiary and Quaternary periods into epochs. In 1841 John Phillips published the first global geologic time scale based on the types of fossils found in each era.

Which is the best example of geologic time?

A well-known period of the geologic time scale is the Jurassic Period, made famous by the film Jurassic Park. The Jurassic Period began around 201 million years ago (Mya), and ended around 145 Mya. During this time, a particular layer of limestone was formed in the Jura Mountains of France and Switzerland.

Which is the largest interval of geologic time?

Eons are the largest intervals of geologic time and are hundreds of millions of years in duration. In the time scale above you can see the Phanerozoic Eon is the most recent eon and began more than 500 million years ago.

Which is the most recent eon in geologic time?

In the time scale above you can see the Phanerozoic Eon is the most recent eon and began more than 500 million years ago. Detailed geologic time scale: The United States Geological Survey has published “Divisions of Geologic Time: Major Chronostratigraphic and Geochronologic Units.”