Geology
The Agro Pontino geologically is one of four geomorphic divisions of a somewhat larger area, the Pontine Region, also comprising the Monti Albani, the Volscian Mountiains and Monte Circeo; in short, all of Roman Latium. The marsh itself was located in Latium Novum, the eastern part of the region, which the Romans removed from the sovereignty of the Volsci. The two terms create some confusion in the literature, as the region was often heavily settled, but the marsh as marsh supported a zero resident population.
Read more about this topic: Pontine Marshes