What is another way to measure the size of Africa?
O
Population
O
Animals
Mountains
Lakes

Is water wet? and is fire on fire?

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks

What geologic process is related to caldera formation?