Falls are usually the free-fall of pieces of rock from a mountain or cliff face. The size of the piece(s) can range from tiny grains to blocks weighing a ton or more. The debris and rock fragements from rock falls collect at the base of the slope as talus. This talus protects the base of the mountain from erosion. On mountains, ice wedging is the main contributor. As water from snowmelt finds its way into the cracks and joints of the rock face, it may refreeze and being to expand. This expansion widens the cracks in the rock. Over time, the cracks have been widened enough so that they are a point of structural weakness. Gravity takes over and the pieces of rock fall from the face of the mountain.
Rock slides can travel a long way from the source of the initial fall
Slides are rapid downslope movements of blocks along a bedding plane, joint, or area of weakness. The blocks tend to break up into smaller pieces as the slide moves downslope and large pieces collide with each other. These pieces can travel a great distance due to the force of the falling rock. Road cuts are susceptible to rock falls and slides when the base of a mountain is removed for the roadbed. So to make the roads safer for motorists, some protective barriers have been designed to catch the falling rocks.