Mars has (perhaps) the largest Avalanches in the Solar System (some on Io have recently been discovered that may beat the conventional avalanches on Mars, but the cryoclastic flows make them look like small rockfalls!)

On Earth, we are familiar with Snow avalanches, which are actually a wide range of flows, all involving snow with admixtures of rock, air, and water.

There are also dry or wet rock avalanches. Many Avalanches occur on Volcanoes  (images here), and if hot lava or magma is involved then the avalanche or debris flow may transform into a pyroclastic flow. Mount Saint Helens is the best documented recent example of this.

A special class of Avalanches is termed "long run-out avalanches" where the debris has travelled further than would have been expected for the volumeand height of the  collapse. Often, some sort of flow involving entrained air or particle interaction is invoked to enable these avalanches to remain fluid and travel longer and faster then normal. These flows are transitional to density flows.

Avalanches on Venus compared to those on Earth and Mars

Avalanches and deposits on Mars.

Click on Image for larger version

Mars has so many large avalanches that underlying processes are concealed. I believe that there is a chronological heirarchy of slides and flows on Mars of progressively diminishing size. The recent avalanches take place in relatively warm (Above 220 K) material from which all the solid CO2 has been purged. As a consequence, Cryoclastic flows no longer develop in the equatorial regions of Mars.
 
 

Late Amazonian -Recent	0-0.7 Ga	Large and small "dry" avalanches and slumps as in images above
Mid Amazonian	0.7 to 2.3 Ga	Very large, long run-out avalanches.  Some cryoclastic channels
Late Hesperian to Amazonian	3.7 to 2.3 Ga	Cryoclastic flows in outburst channels throughout equatorial Mars
Late Hesperian	3.7 to 3.5 Ga	Localised cryoclastic flows in geothermal areas
Early Hesperian	3.8 to 3.7 Ga	Possible regional-scale liquefaction events e.g. Cydonia Initial development of fretted terrain by very large scale collapse.
Late Noachian	4.4 to 3.8 Ga	Closing phase of bombardment - Unstable Atmosphere Layered regolith continues to accumulate Distributory Valley Networks
Noachian	4.6 to 4.4 Ga	Bombardment - Unstable atmosphere.  Formation of thick layered Regolith Possible liquid CO2 at surface under thick atmosphere.

      Created: May 2002
      Last modified: May 2002
      Authorised by:  Head, Earth Sciences

      Maintained by: Nick Hoffman
      Email: nhoffman@unimelb.edu.au