The layer of the Earth called the mantle is often described as convecting. In this context, convection is
A.
a process that keeps the mantle stationary.
B.
a step in the formation of sedimentary rock.
C.
a continuous cycle in the Earth's interior.
D.
a process that occurs on the Earth's surface.

Match your vocabulary word to its definition. 1. emigration 2. immigration 3. migration 4. overpopulation 5. sustainable development 6. under population 7. unsustainable development 8. urbanization the movement from one place to another the number of people exceeds the available natural resources in an area leaving one's homeland to settle in a new place the increase in the population of a city the movement of people to a new country the ability to meet current needs without reducing the ability to meet future needs resources being used up at a faster rate than they can be replenished birth rate insufficient to replace the existing population