The term "Giare" refers in Sardinia to several basaltic plateaus, formed in the Oligocene following volcanic phenomena, characterized by very steep, "escarpment" walls, between Marmilla and Sarcidano. There are three in total: Gesturi, Serri, and Siddi, but the municipalities within whose territory they fall are more numerous. In addition to the three mentioned, the municipalities of Albagiara, Assolo, Barumini, Genoni, Genuri, Gonnosnò, Nuragus, Nureci, Senis, Sini, Setzu, Tuili, and Usellus are also located at the foot of the Giara of Gesturi.
The most famous and extensive of the Giare is that of Gesturi, 12 km long and 4 km wide, covering an area of 45 square km. It has an average altitude of 500 meters above sea level, with the peaks of Zepparedda (609 m) and Zeppara Manna (580 m), ancient lava emission mouths. This plateau has a very uniform surface, marked by some slight depressions, in which water stagnations form during the wet season, sometimes fed by small springs, called paulis. During very heavy rains, they even overflow and create curious waterfalls along the edges of the Giara (particularly copious is Sa Spendula, near Albagiara).
The vegetation that covers the plateau is very lush (these are areas completely devoid of urban phenomena): it consists of dense cork oak forests and a Mediterranean scrub of myrtle, rockrose, strawberry tree, mastic, heather, and euphorbia. It also includes endemic species such as s'erba 'e oru (Morisia monantha), a Tertiary paleoendemism existing only in Sardinia and Corsica, a true living fossil, and Lepidurus apus, a small crustacean that inhabits the summit pools. But the Giara horse is the most famous protagonist of the fauna of this plateau. It is a particular equine breed, with a height at the withers between 110 and 120 cm, introduced in Sardinia in very ancient times, with very particular characteristics, such as almond-shaped eyes. These are the last wild horses in Europe, of which a few hundred specimens remain. Naturally, numerous bird species, 64 in total, plus another 22 only in the summer period, live and nest on the Giara. The toponym (which Wagner linked to the Paleo-Sardinian substrate) would, according to some, derive from the Catalan "haras," indicating with this term the place where herds of horses live.
But the exceptionality of the giare is not limited to geomorphological and florofaunal aspects. The view that can be enjoyed from these plateaus with sheer walls ranges, in fact, from the Gennargentu massif to the Campidano plain, from Marmilla, with its characteristic gentle hills, to the distant sea on clearer days. However, it is the archaeological aspect that constitutes one of the major reasons for interest in the giare. Along the perimeter of the Gesturi plateau, there are 24 nuraghi, while at its feet there are at least twice as many. This fact has led some scholars to consider this territory a sort of natural fortress of the Nuragic populations.
