Volcaniclastic layers interlayered within marine sediments of Early Miocene age have been reported from many sections of the Emilia and Marche Apennines. Ten sections are considered by Borsetti et al. (1979a, 1979b) who emphasize the common explosive volcanic activity ‘at the Oligocene/Miocene boundary’. These volcaniclastic layers were studied during elaboration of doctoral theses dealing with the sedimentology (Amorosi, 1993) and petrography (Tateo, 1992) of Oligocene and Miocene deposits in northern Italy. The presence of volcanic layers within a marine sedimentary sequence and the general goals of the Miocene Columbus Project (Integrated Stratigraphy with particular emphasis on the geochronological—biostratigraphical connection) led us to focus on gathering information on selected sections relevant for integrated stratigraphy.
