The bauxites of southern France--in particular those of upper Var--result from the alteration of lateritic soils formed at the expense of various rocks from crystalline and crystalline-phyllitic massifs (notably the Maures-Esterel of the Brignoles region). The resulting detrital grains are of varied granulometric and mineralogic composition; they have been transported into vast basins formed on surfaces of Jurassic and basal Cretaceous limestone karst into which they were deposited. Various hydrostatic levels in different basins have caused, during the course of diagenesis, modifications in structure and chemical and mineralogic composition (gibbsite, boehmite, and diaspore facies of the bauxites). The intensity of development is related to erosion that has acted mainly in a vertical direction; it has been controlled by subterranean karst drainage. Post-diagenetic effects, such as the mobilization of iron and the formation of terra rossa, have caused the formation of polygenetic soils.

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