The unconformity-bounded units (UBSU) are formal stratigraphic units defined as “body of rocks bounded above and below by specifically designated, significant and demonstrable discontinuities in the stratigraphic succession, preferably of regional or interregional extent” (SALVADOR, 1994); in the National geological map at the scale 1:50,000 (CARG Project) these mappable stratigraphic units are recommended particularly for the continental quaternary successions and for the volcanic rocks (APAT, 2003); however they are also used for not very deformed marine successions (Piedmont Tertiary Basin and outer front of northern Apenninic chain).
In the four examined geological sheets the recognition of unconformities pairs the litostratigraphy. Nevertheless only in the Salsomaggiore Terme and Parma Nord Sheets UBSU are used as mappable units. In the Cabella Ligure Sheet depositional units are defined across the entire basin, where the unconformities pass to their correlative conformities; these units are represented in a Prototype map enclosed to the geological sheet.
The coordination activities carried out for the CARG Project have produced a new cartographic symbol useful for mapping the unconformities also in undifferentiated litostratigraphic units.