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 geologic time scale is divided into (from longest to shortest): eons, eras, periods, epochs and ages.

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: -Geologic time is divided into four large segments called Eons: Hadean, Archean, Proterozoic, and Phanerozoic. The Phanerozoic Eon is divided into Eras: Paleozoic, Mesozoic, and Cenozoic. The divisions among Eras reflect major changes in the fossil record, including the extinction and appearance of new life forms.

Detailed explanation-5: -The geologic time scale is divided into eons, eras, periods, epochs and ages with eons being the longest time divisions and ages the shortest.