Geologists have separated Earth"s background into a collection of time intervals. This time intervals are not same in size like the hrs in a day. Instead the time intervals space variable in length. This is due to the fact that geologic time is divided using far-ranging events in the history of the Earth. For example, the boundary in between the Permian and Triassic is significant by a worldwide extinction in i m sorry a huge percentage of Earth"s plant and animal types were eliminated. One more example is the boundary in between the Precambrian and the Paleozoic i m sorry is marked by the an initial appearance of pets with hard parts.

You are watching: Which interval of time is the longest?

Eons are the biggest intervals that geologic time and are hundreds of millions of years in duration. While scale over you deserve to see the Phanerozoic Eon is the many recent eon and began much more than 500 million year ago. Eons are divided into smaller time intervals known as eras. In the time scale over you have the right to see the the Phanerozoic is divided into three eras: Cenozoic, Mesozoic and Paleozoic. Very far-ranging events in Earth"s history are provided to determine the boundaries of the eras.

Eras are subdivided into periods. The occasions that bound the durations are wide-spread in their extent but are not as far-reaching as those i m sorry bound the eras. While scale above you deserve to see that the Paleozoic is subdivided into the Permian, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician and also Cambrian periods.

Finer subdivisions of time are feasible and the durations of the Cenozoic are frequently subdivided right into epochs. Subdivision of durations into epochs can be done just for the many recent portion of the geologic time scale. This is because older rocks have actually been buried deeply, intensely deformed and severely modification by long-term planet processes. Together a result, the background contained within this rocks can not it is in as plainly interpreted.


The geologic time scale was constructed to visually show the duration of every time unit.

See more: How Do You Say " May Allah Protect You In Arabic, بَارَكَ الله فِيكَ

This was done by making a straight time line on the left next of the time columns. Thicker devices such as thee Proterozoic were much longer in duration than thinner systems such as the Cenozoic.

More Geologic Time range Resources

Geologic Time scale - Geological society of America Geologic Time range from international Commission top top Stratigraphy Visit PALAEO for a thorough discussion Geology soup - university of California Berkeley Geologic Time range - college of California Berkeley Geologic Time scale - united state Geological survey
*