Thus after a heavy rain streams can turn into mudflows as they pick up more and more loose sediment. Mudflows can travel for long distances over gently sloping stream beds. Because of their high velocity and long distance of travel they are potentially very dangerous. As we have seen, mudflows can also result from volcanic eruptions that cause melting of snow or ice on the slopes of volcanoes, or draining of crater lakes on volcanoes. Volcanic mudflows are often referred to as lahars .
Some lahars can be quite hot, if they are generated as a result of eruptions of hot tephra.
Granular Flows Creep - the very slow, usually continuous movement of regolith down slope. Creep occurs on almost all slopes, but the rates vary. They usually remain active for long periods of time. Grain Flows - usually form in relatively dry material, such as a sand dune, on a steep slope. A small disturbance sends the dry unconsolidated grains moving rapidly down slope.