The characteristics of colluvial materials vary according to the characteristics of the bedrock
sources and the climate under which weathering and transport occur. Generally, colluvium is
weakly stratified and consists of a heterogeneous mixture of soil and rock fragments ranging in size from clay particles to rocks a meter or more in diameter.These deposits are often only marginally stable. Because they are found along the lower portions of valley s.ides, such deposits frequently ·need to be partially excavated to allow passage of transportation ดacilities (i:;igure 20-1 ). The resulting cut slop~s are commonly unstable and require constant monitoring and maintenance.