Siliceous screes derived from various sedimentary, igneous and metamorphic rocks occurring on lower slopes in the Mediterranean. Rock debris is often mixed with fine soil. Vegetation cover can be completely lacking or consisting only of bryophyte and lichen communities. In most cases, however, these screes support open vegetation of vascular plants, which tends to be poorer in species than Mediterranean calcareous screes. Natural succession is slower than in temperate screes. Screes overgrown with shrublands or forest do not belong to this habitat.