Proluvium

loose formations that are the products of rock fragmentation and that are carried by streams of water to the foot of highlands. Proluvium forms alluvial fans and, where they merge, proluvial trains. The texture of the detrital material changes from pebbles and gravel with fanglomerates at the top of the fan to finer, more highly sorted sediments, frequently loesslike loams and sandy loams (proluvial loesses), at the bottom.

Proluvium is most fully developed in the foothills of arid and semiarid regions where aleurite-clay sediments (frequently gypsumed and salinized) from flash floods sometimes form on the periphery of the area of proluvium distribution.

The term “proluvium” was proposed by the Russian geologist A. P. Pavlov for deposits, represented by loam-clay loesslike material, from ephemeral mountain streams.