The Apuan Alps are located in the North of Tuscany. They are one of the most interesting area in the Northern Apennines in that they form a tectonic window where the deepest structural layers of the chain can be observed. The Apennines are a thrust-and-fold chain that originated in the tertiary period due to the overlapping from West to East of the Ligurian units onto the external Tuscan and Umbria-Marchigiana domains. The Apuan metamorphic complex is composed of two overlapping tectonic metamorphic unit: the Apuan unit (“Autoctono”) and the Massa unit above. Both have a Palaeozoic basement which a discordant metasedimentary sequence lies upon Triassic-Oligocene for the Apuan units and middle Triassic for the Massa unit.
(text extracted from “The Tuscan marble identities”, published by Regione Toscana, Toscana Promozione, Ministero dello Sviluppo Economico, I.C.E. More information on http://issuu.com)