ABSTRACT

Role of seasonal alternations ƒ In Mediterranean climate, the amount of calcium extracted increases very markedly after a dry period. Observations have shown that desiccation provokes retraction of the clays and detachment of a thin weathered film on the surface of the coarse calcite particles buried in the soil. This film is composed of calcite crystals that dissolution has loosened but has not yet eliminated totally. This promotes their later solubilization (Lamouroux 1970, 1971). Then the phenomenon starts over again. This is not observed in humid climate where the dissolution is direct.