Segnalazione di depositi continentali in corrispondenza di lembi di antiche superfici nell’Urbinate (Marche)

Continental deposits in correspondence of palaeosurfaces in the surrounding of Urbino (Marche, ltaly)

Abstract

Planation surfaces surrounding Urbino are analysed. In correspondence of these, silty-clayey deposits are recognized, sometimes of a considerable thickness (up to 35 m). The finding of some freshwater macrofossils shows the existence of a probable lacustrine and/or alluvial environment, from which these deposits presumably originate. The altimetric distribution of the surfaces, which lie more or less horizontally at 450 m above sea level, makes it possible to hypothesize an origin not connected with a drainage network. The presence of reworked foraminifers, typical of the lower Pliocene, excludes an age prior to this period for these sediments. The constant height of these surfaces would also seem to indicate that the morphogenetic process should not be prior to the last tectonic phase. Finally, the surfaces must be placed in a period prior to the first terraced alluvial phase found in the Marche area.