Question

The spans of time that make up the Earth's geologic timescale are generally defined by the different types of

Answer 1

A.

technologies that humans used at a given time.

B.

foods that humans ate at a given time.

C.

organisms that lived at a given time.

D.

geologic processes that operated at a given time.

Step-by-step explanation:

Answer 2

division of Earth's history into time units based largely on the types of life-forms that lived only during certain periods.