AP BIOLOGY

Detailed explanation-1: -The geologic time scale divides up the history of the earth based on life-forms that have existed during specific times since the creation of the planet. These divisions are called geochronologic units (geo: rock, chronology: time).

Detailed explanation-2: -The history of the earth is broken up into a hierarchical set of divisions for describing geologic time. As increasingly smaller units of time, the generally accepted divisions are eon, era, period, epoch, age.

Detailed explanation-3: -The geologic time scale divides Earth’s history. From a person’s point of view, 4.6 billion years is a tremendous amount of time. To help make sense of it, scientists have organized Earth’s history in a chart called the geologic time scale.

Detailed explanation-4: -The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth’s history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years).

Detailed explanation-5: -Geologists have divided Earth’s history into a series of time intervals. These time intervals are not equal in length like the hours in a day. Instead the time intervals are variable in length. This is because geologic time is divided using significant events in the history of the Earth.