SEDIMENTARY STRUCTURES IN A DEBRIS-FLOW CONE (VARS, SOUTHERN FRENCH ALPS)

An Alpine debris flow cone was investigated with particular reference to the stratification and the sedimentary features. Proximal facies are characterized by a discontinuous stratification due to coarse openwork lenses interlayered with diamicton. These lenses mainly originate from the burying of former channel or levee pavements and external coarse borders of levees. The distal part of the cone presents flat lenses of diamicton corresponding to terminal lobes, paleosols and colluviums. The kind of stratification, the fabrics of stones and the microstructures are significantly different from those produced by solifluction and may be used to recognize fossil deposits.