Modern stratigraphic studies and field mapping of Quaternary volcanic terrains require a multidisciplinary approach for the reconstruction of the time-space history of a volcanic area (e.g., activity phases, eruptive sources, compositional changes, volcano build-up and collapse events) within the framework of concomitant and/or genetically related geological events acting on regional to global scales (e.g., tectonism, climate changes, glacio-eustatism). Here, we report recent results on the stratigraphy, structure, and evolution of the southern part of the Vulsini volcanic district (0.6–0.1 Ma), Roman Province, in the light of a new geological survey for the 1:50,000 map of Italy (CARG Project). We focus on the integration of different kinds of stratigraphic units, including lithostratigraphic, lithosomatic, and unconformity-bounded stratigraphic (UBS) units, to define and group mappable volcanic bodies. Lithostratigraphic units are characterized in terms of textural features, indicative of eruptive and emplacement scenarios, and rock-type compositions. The intervening stratigraphic discontinuities are defined in terms of nature, position, and areal extent, and they are attributed to local depositional processes versus significant temporal hiatuses in the eruptive activity or regional and interregional geological events. The mapped volcanic units are thus correlated to lithosomatic units, corresponding to volcanic source edifices, as well as to the local and regional UBS unit settings recently defined for the Tyrrhenian coast nearby. On these grounds, we illustrate the geological evolution of the study area as the interplay of constructional and destructional volcanic activity, erosion, pedogenesis, secondary volcaniclastic sedimentation during intereruptive periods, and sea-level fluctuations.