THE GEOLOGICAL HISTORY OF SARDINIA IN BRIEF
THE GEOLOGICAL HISTORY OF SARDINIA IN BRIEF
Sardinia is the oldest region of Italy. It is part of the “Sardinian-Corsican block” with Corsica, the only rocky base from a geological point of view very similar to certain areas of the Iberian peninsula (Meseta) and southern France (Montagna Nera). From when the first strips of rock emerged (570 million years ago) until the Eocene (40 million years ago) Sardinia was joined with continental Europe at the Mediterranean coasts of Spain and France.
At the beginning of the Paleozoic era (570-225 Ma), in the Cambrian period (570-225 Ma) its most ancient rocks were formed, due to the accumulation of sediments on the deep seabed. The structure of these rocks underwent a metamorphosis due to the high temperatures of the magmas and the gigantic pressures linked to the movements of the earth's crust, which is why they are called magmatic rocks.
The metamorphic rocks of the Cambrian period (sandstone, limestone, dolomite, schist) are visible in the areas of Sulcis-Iglesiente which were the first lands of Sardinia and therefore have an age of about 600 Ma.
In the following periods, Silurico (435-395 Ma) and Devonico (395-345 Ma) the schistose metamorphic rocks of the Gennargentu massif were formed.
In the Carboniferous (345-280 Ma) massive masses of molten rock emerged through the earth's crust, always consolidating themselves in the subsoil: the granites formed which constitute the true geological backbone of Sardinia.
In the Mesozoic era, in the Triassic (225-190 Ma) and Jurassic (190-136 Ma) periods, the emerged lands of Sardinia were again submerged by the sea: a large amount of carbonate sediments was deposited on the seabed, at great depths. Thus the vast and thick deposits of calcareous sediments were born which then re-emerged giving rise to the spectacular formations of tacchi or toneri of Barbagia, Sarcidano, Ogliastra.
In the Cretaceous period (136-65 Ma) the limestones of the Supramonte di Oliena, the Gulf of Orosei and those of the Nurra-CapoCaccia were formed.
Between the Middle Cretaceous and the Oligocene, plant deposits were formed in the Sulcis areas which will turn into lignite (a type of hard coal) over time.
In the Oligocene (38-26 Ma), due to a complex tectonic event (the Alpine orogeny), the Alps, the Apennines, the Pyrenees and the Atlas chain were born. Sardinia and Corsica, which until then had been welded to the continental mass, broke away from the rest of the continent and, moving in a counter-clockwise rotation, went to place themselves in their current position in the center of the Western Mediterranean.
In the Miocene (26-5.2 Ma) a vast area of the island was again invaded by the sea: the earth's crust stretched out and formed a pit (the Fossa Sarda) extending from the Gulf of Asinara to the Gulf of Cagliari, which was invaded by sea.
In the Pliocene (5.2-1.8 Ma) the part of the ground in which today the Campidano plain is located sank. That was a period of intense volcanic activity found in the vast basaltic flows of Nurra, Anglona, Logudoro-Meilogu, Planargia, Marmilla, Sulcis.
In the Pleistocene (1.8-0.01 Ma) the Campidano rift valley was filled by alluvial debris carried by the rivers that flowed into that sea. Also in the same period there were also several variations of the obstacle line, following the advancing and regressing of the ice that definitively shaped the coastal profile of the island.
