a) What takes place when a body of rock is exposed to the forces and conditions that exist at Earth's surface. b) The process by which water seeps into cracks in a rock, expands on freezing, and thus enlarges the cracks. c) The material that includes organic matter, lies with the top few tens of centimeters of the surface, and is important in sustaining plant growth. d) Unchanneled flow across a surface.
