Rock Glaciers

Rock glaciers are strange features which exist only in high latitudes, and for the most part in rugged mountain terrain.  Sometimes they look like glaciers covered in debris, but some occur in such inappropriate locations that they clearly have nothing much to do with glacier ice or glacial processes.  They can be very large and very spectacular -- but they are inadequately understood.  One requirement for them seems to be the presence of permafrost, or at least a long freezing season.  They are composed, internally, of vast amounts of rock debris with the interstices filled by  ground ice formed by the trickling downwards of melting snow which then later freezes.  Another requirement is that they must have relatively modest precipitation -- so they are found for the most part in relatively arid environments, or in places where snow cannot accumulate in sufficient quantities for snow-patches to accumulate and to be converted into firn or glacier ice.  But they certainly flow just as glaciers do -- and this is apparent on many of the surface features.  Here are three photos of rock glaciers found on the web:

The Mount Sneffels rock glacier, Unites States

Snaefell Rock Glacier, southern Iceland

Rock Glacier near McCarthy, Alaska