Catenary soil relationships on arid hillslopes.

Two compound catenas, on a north-facing slope and on a south-facing slope in an area with 90 mm average rainfall were studied in detail. The slopes were subdivided into two distinct parts. An upper one which is characterized by extensive bedrock outcrops and discontinuous shallow lithosols. The lower part of the slope is colluvial. Vertical and lateral soil differentiation in the colluvium, as expressed by lateral and vertical distribution of secondary carbonates, gypsum and soluble salts, indicate a downslope decrease in the intensity of leaching. The highest intensity of secondary carbonate accumulation occurs at the upper part of the north-facing colluvium where most of the overland flow infiltrates. The pronounced soil differentiation into calcic and gypsic horizons suggests a relative high stability with slow rates of erosion and deposition in the colluvium. -from Authors