Late quaternary evolution of the Terni basin, Central Italy: new geoarchaeological data

Abstract

Bertacchini M., New geoarchaeological data on the recent evolution of the Terni basin, Central Italy. (IT ISSN 0394-3356,
2009).
Because of an archaeological find of part of a Hellenistic city wall (ca 5th -3rd century BCE) a well-preserved 10 m thick fluvial sequence
was studied close to the centre of the town of Terni, in an area of Central Italy (Umbria) where the geological outcrops are generally
scarce. This study was made in a large excavation for a building that permitted direct observation of the sediments that filled the Terni
basin and provided a step forward in our knowledge of its geoenvironmental evolution. The sedimentary sequence was deposited by a
segment of the ancient Nera river-course (paleo-Nera) in the Late Pleistocene-Early Holocene and its presence is correlated with the
development of the first human settlements in the town of Terni. This fluvial sequence shows evidence of a low-sinuosity gravel meander system consisting of transverse gravel bars and gravel sheets in its lower part, that are capped by a 5 m thick levee unit and overbank deposits interbedded with incipient paleosols and a crevasse channel unit. The floristic composition contents in the paleosols of the overbank sequence provide important information on the climatic transition from the Late Glacial to the Holocene. The upper part of the sequence, a paleosol dated with archaeological remains to Roman times, contains important elements that aid in understanding the development of the first phases of urbanisation of the ancient town of Terni.