====Umbrian-Marchean Apennines====A natural border exists between the Northern Apennines and the Central Apennines: a klippen zone, or band of isolated Liguride rocks, follows the Val Marecchia ("Valley of the Marecchia River") to the Marches-Tuscany border and passes through the Monti Rognosi and Arezzo in Tuscany.
Geološka definicija pa ni ista kot geografska.