Which sentence best describes mass movement?
a. the downhill movement of animals due to heavy snow in their normal home
b. the movement of people from new jersey to ohio
c. the downhill flow of soil and rock resulting from gravity
d. the steady pace of air bouncing off a mountain

1. crust 1 the metallic layer at the earth's center 2. inner core 3 the firm layer between the crust and the asthenosphere 3. lower mantle 2 the layer surrounding the inner core 4. asthenosphere 4 the semi-solid layer between the top layer and the upper mantle 5. upper mantle 5 the layer between the asthenosphere and lower mantle 6. top layer 6 the earth's outermost layer 7. outer core 7 the hottest part of the mantle