GEOLOGY

   The geological framework of ancient Etruria had an important constraining effect on the political framework in which the Etruscans developed. A first key structural feature of Etruria is the presence of the Apennines, which contain Etruria, Umbria, and the Sabine and Faliscan territories from the east. Etruria broadly occupies the more lowland areas between these uplands to the north, the Tiber River to the east, and the Tyrrhenian sea to the west. Neotectonics, that is the relative youth of mountain building, have led to a considerable verticality of the landscape on the northern flanks where there was also access to the Po Valley through the Mugello, and dynamic effects of geomorphology. The structure of geological relief profoundly affected communications. For instance, the line of the Via Flaminia, after leaving the volcanic landscape of South Etruria followed the natural tectonic valleys of Umbria, seeking out a pass in the Apennines to find an exit to the Adriatic Sea. The drainage, and thus the placing of the rivers, of Etruria is also determined by the nature of the structural relief. Extensive alluvial plains are rare, but exist within Etruria and include the mouth of the Arno River and the Maremma. Another feature is the presence of tectonic basins to the northeast of Etruria, usually containing rivers such as the Mugello and Casentino, and the Chiana Valley.

   See also NORTH ETRURIA; SOUTH ETRURIA; CLIMATE.