Slumps frequently form due to removal of a slope base, either from natural or manmade processes. Stream or wave erosion, as well as road construction are common instigators for slumping. It is the removal of the slope's physical support which provokes this mass wasting event. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.