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

a mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. this uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.a geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged.