Answer:
Scientists began to mark division on the geologic time scale when patterns and similarities started emerging from archeological studies. Patterns such as the discovery of fossils that were formed within the same period.
Explanation:
Geologists who study matter that make up the Earth's crust (whether solid gaseous or liquid), as well as matter from other terrestrial planets and the processes that influence the formation and condition of this matter, are called geologists.
They have successfully calibrated history into various phases of time intervals. These intervals are event-based intervals. For example, you have Eons, Eras, and Periods.
An Eon is a billion years. An example is the Neoproterozoid Eon. Eons are made up of several Eras and Eras are made up of periods. An example of an era is the Mesozoic era. Whilst periods are smaller units of an era, eg. Triassic era.
As scientists deduced the causes for the formation of fossils and topographical remains/patterns, they collected events that occurred within the same time period and group them together.
This range of events became known as the geological time scale.
The age of fossils and rocks is also used to map out the calibrations on the scale.
The age of fossils and rocks is determined using the process of radioactive dating.
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