DOLOMITES, THE, a mountain district in the South Tirolese Alps, and a subdivision of the Alps. The mountains are formed of dolomite (magnesian limestone), which rises in peaks of a singular degree of sharpness and streaked by veins of start ling colours. It is well known to tourists. Most of the more striking peaks were first ascended in the late sixties and early seventies of the 19th century by English mountaineers. Roughly speaking (from west to east) the Dolomite region lies between the Brenner railway from Franzensfeste to Trent and the road over the Monte Croce Pass from Innichen in the Drave valley by way of the Sexten glen and the Piave valley to Belluno and Feltre. On the north it is limited by the railway line from Innichen to Franzensfeste, and on the south by the railway and road from Trent to Feltre. The highest summit is the Marmolata (10,972 ft.), but far more typical are the Sorapis, the Cimone della Pala, the Langkofel, the Pelmo, the Drei Zinnen, the Sass Maor and the Rosengarten (see ALPS). Among the chief tourist resorts are St. Ulrich (in the Groden valley), San Martino di Castrozza (near Primiero), Caprile and Cortina d'Ampezzo.
Besides the Dolomites included in the above region there are several other Dolomite groups (though less extensive) in the Alps. North-west of Trent rises the Tosa group, while in Switzerland there are the Piz d'Aela group, south-west of Bergiin on the Albula Pass route, and the curious little group north of the village of Spliigen, besides other isolated peaks between the St. Gotthard and Lukmanier Passes. In Dauphine itself (the home of the geologist Dolomieu) the mountain districts of the Royan nais, of the Vercors, and of the Devoluy (all south-west of Grenoble) are more or less Dolomitic in character.