Stratification mechanisms in slope deposits in high subequatorial mountains

An analysis of the processes active in the frost environment of high subequatorial mountains makes it possible to propose a model for the stratification of slope deposits. Bedding is generated by solifluction sheets which move at the speed of a few cm y-1. Solifluction involves needle ice, frost creep and gelifluction, and the ground thikness concerned is less than 20 cm. Sorting takes place by frost heaving. Coarse particles are concentrated at the front of the sheets, where matrix materials tend to be washed away, and are then buried by the advancing fine layer. Sedimentary characteristics allo recognition of several diagnostic features which can be used to indicate the origin of bedding in relic slope deposits situated in mid-latitudes. This model offers an alternative to earlier concepts of the stratification of slope deposits, but further studies are required, since other processes may also generate similar bedding geatures. (Résumé d'auteur)