The second subdivision of the Tertiary Period (Eocene, Miocene, and Pliocene) by Charles Lyell in 1833; the fourth in a more modern sevenfold subdivision (epochs) of the Cenozoic Era; and the first epoch of the Neogene Period (which includes in successive order the Miocene, Pliocene, Pleistocene, and Holocene). The Miocene represents the interval of time from the end of the Oligocene to the beginning of the Pliocene and the rocks (series) formed during this epoch. The Miocene was originally considered as a biostratigraphic (rather than temporal) entity, to unite rocks containing 20–40% extant molluscan species. Lyell based his concept of the Miocene primarily on the shallow marine sediments and associated molluscan faunas in the Superga Hill of northern Italy (near Turin), as well as other Piedmont localities and outcrops in southwestern France (Aquitaine Basin), Touraine, and the Vienna Basin.