The italian Southern Alps, as other chains surrounding the Mediterranean realm, were deeply eroded during the Messinian salinity crisis, as a consequence of the rapid drop in sea level. The successive Pliocene marine transgression reached the present southernmost margin of the Venetian and western Friulian plain, where the Messinian paleovalleys were infilled with progressively more proximal deposits. Our investigations have been focused on petrographic signature of ancient (Upper Messinian) fluvial deposits compared with the modern river sands in order to evaluate the changes of supplies along some important directories. These data have been integrated by detrital apatite fission-track analysis, which uses the fission-track age of single grains to identify their source region. On the basis of this approach, we present a schematic temporal and paleogeographic evolution of the Venetian–Friulian plain during the last 5 m.y.