Erosión y desertificación.-Minor Forms in a Badlands Landscape Framework

Abstract

ABSTRACT We describe and classify some medium-scale erosional morphologies in badlands areas. They have been categorized in three different types: A) Surficial forms on horizontal surfaces (soil surface crusts, cracks, popcorn) and walls (“slips”, pseudo-stalactites). B) Punctual fingerprints: rain impact and micro-collapses (dimples). C) Ruiniform morphologies (caves, shelters, residual pinnacles). The A-type shapes are caused by damping-desiccation phenomena on clayey soils; morphologies on walls are due to laminar runoff on weak lithologies (clay, loam), also dubbed pseudo-speleothemes. Their scale is centimetricdecimetric. B-type forms may be an external passive process (impact) or an internal dynamic process (dimples) occurring in granular sediments inside shelters, in conditions of apparent calm, measuring up to a few centimetres. The caves and shelters of type C generally involve an excavation following stratification or jointing planes, while the residual pinnacles are vertical forms linked to advanced piping and fluting. Both forms are decametric in scale.