I TERRAZZI DELLA MEDIO-BASSA VALLE DEL F. VELINO

Abstract

In the frame of the Rieti Basin research program, be­tween Canetra and Le Marmore, four different fluvial and fluvial-lacustrine terraces have been recognized in the Veli­no Valley. They cut the villafranchian and post-villafranchian sediments and some of them can be connected with a traver­tine threshold. The terraces occur at 500, 440, 420 and 390 m above see leve! respectively. The presence of volcaniclastic levels within the first and second order terraces deposits, referrable, on the basis of chemical-mineralogical characteristics, to the explosive ac­tivity of peri-tyrrhenian volcanism, allows to date them to the Middle Pleistocene. The third order, on the base of dat­ings carried out on the travertine deposits (U/Th), are dated late Pleistocene. Datings of travertine deposits and amino acid analyses, carried out on fresh water shells allowed to ascribe the deposits of the last order, connected with the Marmore threshold, to the Holocene.