13. pieces of earth's crust move on top of the a. ocean b. mantle c. outer core d. inner core 14. the fact that ice floats on top of water is like the fact that a. the mantle causes earthquakes and volcanoes b. the mantle is colder than the crust c. the less dense crust sits on top of the mantle d. the crust is melting 15. a map of global earthquakes and volcanoes tells you a. where the edges of the continents are b. where the earth is the hottest c. nothing, it looks random d. where the plate boundaries are open

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation:

the wetland preservation movement began in the u.s. in earnest with the clean water act (cwa) of 1972. although not specifically written to protect wetlands, the cwa is comprised of a series of regulations designed to prevent pollutants from contaminating u.s. waters.