Tentative de chronologie des formations superficielles du versant sud de la vallée de La Ballongue (Pyrénées ariégeoises) : Applications à la genèse du milieu souterrain superficiel

The MSS (superficial underground compartment) corresponds either to a weathering of the bedrock or to a scree slope regardless of the nature of the bedrock. One of the essential characteristics of the MSS is the presence of heterogeneous voids in the rocky material lying underneath the soil. In order to know the geodynamics and evolution, chronological markers (3 weathering and pedogenesis degrees) were researched in three terraces scraps. These degrees of weathering and pedogenesis allow to propose a slope dynamic. The formation of superficial underground compartment (MSS) appears to be dependent on this slope dynamic. The MSS is originated fiom a morphogenesis phase characterised by a cryoclasty period (Late Glacial), responsible forvoids, and followed by a pedogenesis phase beginning at the Holocene, which produced a soil above the MSS.