Final answer:
Geologic time is organized into divisions such as eras, periods, epochs, and ages based on major changes in geology, climate, and the evolution of life.
Step-by-step explanation:
The divisions of geologic time, such as eras, periods, epochs, and ages, are used to organize Earth's history based on major changes in geology, climate, and the evolution of life. The geologic time scale divides time into eons, which are then subdivided into eras. Eras are further divided into periods, then epochs, and finally ages.