**4. Results**

*4.1. Geological Setting of the Coroglio-Trentaremi Sea Cliff*

The geological setting of the Coroglio-Trentaremi sea cliff is reported in Figure 3, whereas the stratigraphical relationships between the outcropping rock-types are reported in the stratigraphical columns of Figure 4 and in the geological cross-sections of Figure 5. The sea cliff is mainly cut in tuffaceous deposits of the NYT and in older volcanics, that are mantled by unconsolidated post-NYT pyroclastics.

The oldest volcanic unit consists of whitish and stratified tuff deposits, made of a pre-NYT ash, pumice and scoriae (Figure 3), which outcrops in the Coroglio area, to the west, and at Punta Cavallo and Trentaremi bay, to the east (stratigraphical columns A and B in Figure 4). Geological cross-sections A-A', B-B', L-L' and M-M' in Figure 5 show that this unit forms a morphostructural low where the more recent pre-NYT ashy unit and the NYT accumulated. This unit is strongly inclined in the surroundings of the Trentaremi bay (dip around 45◦) and its bottom is made of boulders, scoriae and large pumices, suggesting that this area is pretty close to the possible source area, as has been already hypothesized by Cole et al. [60]. The unit continues upward with greyish-whitish, pisolithic ashes and pumices, with interbedded large pumice-rich layers, whose bedding ranges from planparallel to gently dipping and slightly undulating. The base of this unit is not recognizable, whereas its top surface has a probably erosional origin. The age of this unit ranges between 37 ka and 15 ka and is constrained at 20.9 ka by Scarpati et al. [61] (Figure 3).

The pre-NYT ash, pumice and scoriae deposits pass upward to a mainly ashy unit, which has been named pre-NYT ash deposits in Figure 3. This unit outcrops to the west of the study area, near Punta d'Annone (geological cross-sections A-A', C-C' and D-D' of Figure 5) and its thickness ranges between 20 and 30 m (stratigraphical column D in Figure 4). It consists of an alternation of horizontally stratified ashy layers and undulated scoriae rich and ashy layers probably of fall origin. This unit is either not reported in the literature or it is grouped with the NYT [35], its age ranges between 37 ka and 15 ka, and it is tentatively correlable with the Whitish Tuff of Scarpati et al. [62], which is dated at 19.7 ka (Figure 3).

The pre-NYT ash deposits pass upward to the NYT, which outcrops in the entire study area, with thickness ranging from 30 m (to the east, near the Trentaremi bay) to 80–100 m (to the west, near the Coroglio sea cliff) (Figures 3 and 5). It consists of lithified pyroclastic deposits made of pumices, lithics and cm-sized scoriae, yellowish to greenish, in a yellowish ashy matrix [63]. The unit is massive (as a typical pyroclastic flow deposit) being just locally thinly layered and with abundant sub-vertical fractures. The top surface of the NYT is a low-dipping erosional surface and its age is 15 ka [12].

The NYT passes upward to fall deposits related to Phlegrean eruption which occurred in the last 15 ka [43,60], which have been named post-NYT pyroclastics in Figure 3. This unit consists of an alternation of decimeter thick sandy and ashy layers and centimeter thick layers rich in whitish pumices with interbedded thin paleosols that testify to a period of quiescence of the eruptive phases. A paleosol also occurs between the top surface of the NYT and the base surface of the post-NYT pyroclastics. The top surface of the post-NYT pyroclastics is almost flat and corresponds with the topographic surface (Figures 3 and 5). The thickness of this unit is not uniform (Figure 5), ranging from 10–15 m (to the east, near the Trentaremi bay) to 40 m (to the west, near the Coroglio sea cliff), and its age is younger than 15 ka (Figure 3).

The sea cliff foothill, from the Coroglio area to the Trentaremi bay, is mantled by slope debris, landslide bodies and beach deposits, which are mainly located near the Trentaremi bay and whose maximum thickness is around 20 m (Figure 3 and stratigraphical column C in Figure 4). Moreover, landslide deposits consist of reworked ashes with NYT blocks, whose size may exceed some cubic meters, and are due to rock falls affecting the sea cliff, some of which are very recent as suggested by the lack of vegetation and the low erosion by sea waves.

**Figure 4.** Stratigraphical columns representative of the geological setting of the Coroglio-Trentaremi sea cliff base. Location of stratigraphical column is reported in Figure 3. Inset scheme in the lower right corner of the figure shows stratigraphical correlation between stratigraphical columns.
