The landslides in the thick colluvium behave more or less as we would predict from laboratory measurements of residual strength of the colluvium. We know of no examples in which thick landslides have moved more than a few meters during any given episode of movement. More commonly, the total displacement during a movement episode is only a few centimeters. A force-displacement diagram for the thick landslides (fig. 18) illustrates the concept that the maximum mobilized resistance to sliding is residual friction. The cause of the difference in behavior between the two landslide types could be due to a small amount of residual cohesion and/or roughness of the failure surface and perhaps tree roots.