Question 1
Sea level is constant over long periods of the earth's history, and that makes it ________ as a major datum for mapping elevations.
◦ unuseable
◦ indispensable
◦ only occasionally useful
◦ critical
Question 2
Fossil fuels are especially abundant in ________ rocks.
◦ Cenozoic
◦ Mesozoic
◦ Paleozoic
◦ Precambrian