Final answer:
The geologic time scale organizes Earth's 4.57 billion-year history into eons, eras, periods, epochs, and ages, representing major changes in geology and life, and is used by geologists to categorize significant geological and biological events.
Step-by-step explanation:
The geologic time scale is used to organize Earth's history, which is approximately 4.57 billion years, into chronological divisions that represent significant geological, climatic, and biological events.
- The scale is divided into eons, which include the Hadean, Archean, Proterozoic, and Phanerozoic, with the first three eons collectively known as the Precambrian 'super' eon.
- Each eon is further subdivided into eras, periods, epochs, and ages, reflecting major changes in Earth's geology and the evolution of life, such as the extinction of dinosaurs.
Geologists rely on radiometric dating to determine the ages of these divisions. A project to create a geologic time scale involves using a roll of paper to visually represent these periods and significant events at a scale of 1 cm to 20 million years. Such a project helps students understand the vastness of geologic time and the distribution of Earth's history.