In this case study of the Marcandreola site, located on a natural pathway along which the ancient settlement developed, the authors identify a break in occupation of almost 150 years from the middle to the late Republican period. Analysis of a thick debris flow deposit which covers one of the two Archaic roads revealed that it resulted from a sudden and imposing flow of water with high carrying capacity. Archaeological artefacts within the deposit establish a tpq of the third century BC. High water run-off cannot account for the deposit and associated mud- and debris flows (lahars) indicate that volcanic activity in Lake Albano must have continued long after the late Pleistocene. The issue of the emissary from the lake mentioned by Livy 5.16 might need to be re-evaluated.
C. C.