*Introduction to the Sedimentary Geology, Genesis, and Evolution of the Pontine Plain in Relation… DOI: http://dx.doi.org/10.5772/intechopen.111683*

had reached the Lepini and Ausoni carbonate reliefs, which were still in the uplift phase. Mount Circeo was a limestone island separated from the mainland by a large area of sea (**Figure 5A**). The sediment contributions of the drainages flowing into the sea and the contribution of clastic materials linked to the initiation of activity of the Alban Hills volcano caused the first partial filling of the marine basin and the formation of a series of coastal bars. The volcanic activity of the Alban Hills began shortly before the beginning of the Pleistocene (**Figure 5B**). The lowering of sea level associated with the onset of the cold climate phases of the Pleistocene caused the shoreline to advance approximately 10 km. The entire area was transformed into a marshy area with some water courses that reached the sea and formed incised valleys. The volcanic activity at Alban Hills continued (**Figure 5C**). With the marine transgression that began 10,000 years ago at the end of the Würminaglacial stage, the shoreline regressed, assuming an articulated trend by occupying the previous river valleys. The deposition of new coastal strips led to the formation of a new, different, and more rectilinear shoreline with the isolation of the Fogliano, Monaci, Caprolace, and Paola Lakes (**Figure 5D**, **Table 1**). Dunes separated the lakes from the sea, as can be seen in the case of Circeo (**Figure 6A**). A geomorphologic model for Pontine Lake (Sabaudia, **Figure 6B**) was constructed. **Figure 7** shows digital reconstructions of the Pontine Plain with coastal lakes formed during the regression of the coastline during the Holocene. Moreover, the warm period brought erosion of the coastline, which is still occurring.


#### **Table 1.**

*Ice age succession with the sedimentary terranes formed.*

#### **Figure 6.**

*A recent coastal dunes. B Sabaudia Lake model. 1-sandy deposits; 2-sandbar of recent dune; 3-current lake silt– sand deposits; 4-current beach. Modified from the http://www.zaininspalla.it/articoli.php?url=articoli/geologia/ circeo.htm&titolo=Note%20geologiche%20e%20geomorfologiche%20dell%E2%80%99area%20pontina&PHPSES SID=frpledcgn761q5jl2ljspo9gf1.*

*Introduction to the Sedimentary Geology, Genesis, and Evolution of the Pontine Plain in Relation… DOI: http://dx.doi.org/10.5772/intechopen.111683*
