Relicts of the Pleistocene Po Plain on the Western and Southern slopes of Turin Hill (NW Italy)

A detailed geological survey of the Southern slope of Turin Hill reveals a Pleistocene terraced fluvial succession consisting of flat surfaces separated by scarps with associated fluvial clayey--silty and gravelly sediments. This succession is not linked to the present N--S hilly streams, but is instead related to major Pleistocene W--E rivers. The collected regional data suggest an ancient trend of the Po River flowing across Turin Hill, prior to its present course to the north of the hill. The Pleistocene terraced fluvial succession of the Western slope of Turin Hill is also mapped, based on a previous survey to allow a full reconstruction of the ancient rivers. The collected regional data and the petrographic analysis show that this succession is related to an ancient tributary of the Po River (Dora Riparia River). Wide saddles of the same river have been mapped on the main watershed between the two slopes of Turin Hill. The capping of soils less evolved with decreasing elevation over the fluvial sediments and landforms indicates that the whole terraced succession covers a large time range (Middle--Upper Pleistocene). The reported geologic successions and the current morphology of the relief result from the uplift and deformation of the Pleistocene Po Plain and the Dora Riparia Plain that were shaped at the south of Turin Hill. The proposed age/elevation relationships for the mapped terraces suggest a remarkable uplift of Turin Hill during the late Quaternary.