Mountains

All the mountain peaks have the aspect of high ledges without summits in do not reach 2000m in any place, in fact, the highest peak is the Punta La Marmora (1834m) in Gennargentu, followed by the Punta Balestrieri (1259m) in Monte Limbara in Gallura.
The predominant forms of relief in Sardinia are the high plains: the longest high plain is that which obliquely crosses the island from Monte Ferru (OR) to the mountains of Alà, Buddusò and Bitti, while the highest plain is that of Fonni.
The atmospheric conditions have up to the present day rendered irregular the granite relief shaping, by way of slow capillary decomposition, niches of varying size such as the tafoni. Some of these are so large that they are used by both animals and man as shelter.
Other unusual rock formations derived by the elements are inselbergs; isolated mountains free from any vegetation. Typical examples of these inselbergs can be found in the coastal plain of Lotzorai. Minor high plains are basaltic, like the marshes of Gestori, Serri, Siddi and Tecu (Barisardo): made up of a cover of basaltic rock that derives from the expansion of volcanic lava over the sedimentary Miocene land.
The limestone and dolomite formations of the Mesozoic era have a specific postion around the Gulf of Orosei, that form the mountains of Oliena and Monte Albo. Imposing for their height and dimension are the formations of Tonara and the "heels" of Ogliastra. These mighty masses have broken into great fragments or picturesque towers (the most noted is that of Perda Liana (1293m) of numerous vertical pillars; they reach high altitudes and are pale and bare and create the borders of the canyons. The most impressive examples on the island are found in Ogliastra, precisely in Baunei (Codula di Luna and Codula di Sisine) and Urzulei (Gorropu).
Among the limestone formations we find important geological phenomenon. The internal morphology (ipogea) prevails over the external (epigea); in fact they rarely form major superficial cavities but rather caves with underground streams.
In the "heels" of Ogliastra, these phenomenon have developed in a predominantly horizontal way because of the rather modest width of the limestone formations.
Some of the most beautiful caverns of Sardinia pass under the Supramonte of Baunei: Su Palu, Il Miracolo, del Fico, di Istrizili, di Mangalistru, with great underground ambients rich with small lakes, stalactites and stalagmites. In the area of Ulassai we find the noted cavern of Su Marmuri (meaning "of marble" for its white stalactites), with an abundance of salt up to levels of around 80m and housing an underground lake, stretching for almost a kilometre. Another cavern of notable splendour is the cavern of Bue Marino (Dorgali) where the few examples of monk seal seek refuge. The vertical cavern of di Sterru, found in the valley of Golgo, is the deepest in Europe (330m). It's origin is thought to be that of the previous mentioned geological phenomenon.