Mass+Wasting

Mass Wasting
 * **Slope Failures** ||
 * * **//Slumps (also called Rotational Slides)-//** types of slides wherein downward rotation of rock or regolith occurs along a concave-upward curved surface (rotational slides). The upper surface of each slump block remains relatively undisturbed, as do the individual blocks. Slumps leave arcuate scars or depressions on the hill slope. Slumps can be isolated or may occur in large complexes covering thousands of square meters. They often form as a result of human activities, and thus are common along roads where slopes have been oversteepened during construction. They are also common along river banks and sea coasts, where erosion has under-cut the slopes. Heavy rains and earthquakes can also trigger slumps. || [[image:http://www.tulane.edu/~sanelson/images/slump.gif width="293" height="268"]] ||


 * * //**Falls**// - //**Rock falls**// occur when a piece of rock on a steep slope becomes dislodged and falls down the slope. //**Debris falls**// are similar, except they involve a mixture of soil, regolith, vegetation, and rocks. A rock fall may be a single rock or a mass of rocks, and the falling rocks can dislodge other rocks as they collide with the cliff. Because this process involves the free fall of material, falls commonly occur where there are steep cliffs. At the base of most cliffs is an accumulation of fallen material termed //**talus.**// || [[image:http://www.tulane.edu/~sanelson/images/rockfall.gif width="293" height="268" caption="RockFall.GIF (8317 bytes)"]] ||

The term "mass wasting" in geology is used to describe any process that moves mass under the influence of gravity. It includes the common term "erosion", but excludes the term "[|weathering]" which is used to describe process that take place on site with no net mass transfer. Mass wasting can take many forms, from a deadly mudflow rushing down a mountain slope, to destructive landslides which in a few seconds deliver tons of debris, to more subtle forms in which the downslope movement is almost imperceptible. [|Click Here] to view a video of landslides.
 * * //**Slides (also called Translational Slides)**// - Rock slides and debris slides result when rocks or debris slide down a pre-existing surface, such as a bedding plane, foliation surface, or joint surface (joints are regularly spaced fractures in rock that result from expansion during cooling or uplift of the rock mass). Piles of talus are common at the base of a rock slide or debris slide. Slides differ from slumps in that there is no rotation of the sliding rock mass along a curved surface. || [[image:http://www.tulane.edu/~sanelson/images/slides.gif width="293" height="268" caption="Slides.GIF (11197 bytes)"]] ||

[|Click Here] to view a powerpoint on mass wasting.