The Geologic Time Scale is Often Subdivided on the Basis

Question

The geologic time scale is often subdivided on the basis of ____.  
A) the appearance of different radioactive isotopes in different strata
B) levels of background extinction
C) periods of extensive environmental change
D) the appearance of new species
E) climate change

Accepted Answer

The geologic time scale is subdivided into different periods based on periods of extensive environmental change, such as the rise and fall of sea levels, mass extinctions, and shifts in climate patterns. This helps scientists to understand how the Earth's environment has changed and evolved over time. While the appearance of new species and radioactive isotopes are important events in the history of the Earth, they are not typically used to divide the geologic time scale into different periods.