Sand, silt, and clay carried by a tornado fall to the ground along with other debris when the swirling wind stops. this is a good example of what?
a. weathering
b. soil formation
c. erosion
d. none of the above

A. Weathering best fits this scenario, through the action of wind, material is moved and transported across lan, and example of weathering. 

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.