The age of one rock layer compared to the age of another rock layer is its
a. comparative age
b. relative age
c. actual age
d. conformity

Where does the availability of water pose the greatest problem

In the late 1990s, brazil’s poor people protested about crowded cities land distribution mining permits industrial pollution

Which revelation resulted from the observation of the spectrum of different galaxies? a. there were more galaxies whose spectrum was blueshifted b. there were no galaxies whose spectrum was redshifted c. there were more galaxies whose spectrum was redshifted d. there were no galaxies whose spectrum was blueshifted