It will be remembered that two years ago, in 1907, I pointed out the occurrence of important planes of overthrust at the base of the Dolomite Mountain-massive of Langkofl and Plattkofl in South Tyrol, which explained its apparent ‘reef-like’ form, and its curious position above Wengen lavas in some places and Muschelkalk at others. I showed that at Langkofl the Upper Werfen Strata and Muschelkalk form a shear-slice above which the Schlern Dolomite rocks of the Langkofl Mountain have been overthrust, and below which the Wengen lavas and tuffs of the Ciampinoi meadowland are present; also that the planes above and below this shear-slice are crush-planes of extremely low inclination.