Geologists organize the 4.6 billion years of earth's history into sections based on important changes seen in the geologic record. The largest intervals are eons, with each eon composed of many millions of years.The geologic timescale is continually being revised by new research and more accurate dating methods.
Down below is what I had made after many different explanations and answers :)
Explanation:
Scientists need to first understand that the laws of nature stay the same and have stayed the same for many years. They formed the geologic scale by using important discoveries to understand and separate it into different sections based on what they found in those eras. The largest intervals are eons being of millions of years. Scientists studied fossils in rock that support that time period and record it, and order it with their estimated age of time.
The scale is organized by 4.6 billion years into time sections that are named with the fossils found for that time period. During the Precambrian time the process of eroding the surface have lessened, there used to be meteors that used to hit the earth that survived the atmosphere, now the atmosphere is harsh enough to break down meteors with the rocks surrounding it and break down even further to small rocks when entering earth's atmosphere.
