Val di Chiana

thumb|View of Valdichiana thumb|The temple was built by Grand Duchy of Tuscany Cosimo I de Medici on the plain of Scannagallo, in [[Foiano della Chiana, surrounded by the Fattoria Santa Vittoria vineyards.]] The Val di Chiana, Valdichiana, or Chiana Valley, formerly Clanis Valley, is a tectonic valley of central Italy, whose valley floor consists of important alluvial residues filled up since the 11th century, lying on the territories of the provinces of Arezzo and Siena in Tuscany and the provinces of Perugia and Terni in Umbria.

==Morphological formation of the Clanis (Chiana) Valley== The valley, of tectonic origin with extension on the western side and compression on the eastern one, was mainly formed during the Miocene. In the Pliocene it was almost entirely submerged by the great Pliocene sea. Once it had withdrawn, in the upper Villafranchiano (about two million years ago) central Italy hosted large lakes, including that of the Chiana basin which was short-lived as it was drained (at the beginning of the Pleistocene) by the erosion of the hilly threshold of its waters, to take the form of a canyon crossed by a river, tributary of the waters of Lake Trasimeno (whose formation ended 110,000 years ago). During the Pleistocene, the Chiana valley was a tributary of the waters of the ancient Lake of Quarata (i.e. of the Arno) until 150,000 years ago, being along its course the Lake of Montepulciano and the Lake of Chiusi, very deep, whose hydrometric "zero" was located at a lower altitude (20-25 meters) than the current one. Its valley floor was very hollow in the centre, with a "V" shape due to western tectonic extension, eastern compression and progressive erosion determined by the transit of water towards the south, as evidenced by core samples and geological studies, even recent ones, and was furrowed by the so-called "Arno Tiberino" before that its waters were captured by the current riverbed towards Incisa and Florence.