Weathering and morphogenesis in a mediterranean climate, Calabria, Italy

Deeply weathered plutonic rocks occur widely in the Sila Massif, Calabria, southern Italy. Three representative weathering profiles developed on the h illtops indicate that sand represents more than 50% by weight throughout mo st of the weathering profile, and silt- and clay-size fractions are also we ll represented, filling the interstices among corestones. Both sand, and fi ner fractions of grus, and soil horizons, are thought to be derived from a combination of granular disintegration and chemical decomposition, develope d on relatively flat terrains of the Sila massif. These slopes are now expe riencing transport-limited morphodynamics, under a montane-modified Mediter ranean climate. The depth of the weathered layers, that have suffered littl e erosional truncation, typically exceed 15 m, and may reach 50-60 m or mor e. Major isolated or grouped exfoliation boulders are the most common minor landform feature developed on the Sila massif granite. Boulders have devel oped as a result of spheroidal weathering and by removal of the sandy-textu red granite. The Schmidt hammer (SH) test on boulders and corestones, sugge sts three distinctive degree of weathering (from moderately to completely w eathered rock), and that biotite content is the major controlling factor of the granite mechanical behaviour. Understanding of the dynamics of this we athering system is crucial to the interpretation of the complex suite of va riables that control landscape evolution of granitoid terrains. (C) 2000 El sevier Science B.V. All rights reserved.