The time units used by scientists to divide Earth's history are part of the
A. 180° longitude.
B. geologic time scale.
C. 360° latitude.
D. 24-hour model.
The time units used by scientists to divide Earth's history are part of the "geologic time scale," since when measuring extremely long time-spans, it is often helpful to look to the Earth's crust for clues of life from the past.
