NEET BIOLOGY

Detailed explanation-1: -The geologic time scale is the “calendar” for events in Earth history . It subdivides all time into named units of abstract time called-in descending order of duration-eons, eras, periods, epochs, and ages.

Detailed explanation-2: -What does the time scale represent? 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-3: -Fossils are fundamental to the geologic time scale. The names of most of the eons and eras end in zoic, because these time intervals are often recognized on the basis of animal life. Rocks formed during the Proterozoic Eon may have fossils of relative simple organisms, such as bacteria, algae, and wormlike animals.

Detailed explanation-4: -By investigating the layers, they also uncover fossils of organisms that lived in the past. By examining where in the rock layers fossils are found, scientists have been able to put together the geologic time scale, which is used to explain Earth’s 4.6-billion-year history.