1. what length of time does the geologic time scale cover?
a. 2.0 million years
b. 4.6 billion years
c. 20.5 billion years
d. 10.1 million years

2. the largest expanse of time on the geologic time scale is
a. eon
b. epoch
c. era
d. period

3. which eon of the geologic time scale means "visible life"?
a. phanerozoic
b. proterozoic
c. hadean
d. archean