Surface S3. S3 is the shallowest stratal surface found in the Venice Lagoon succession. It shows characteristics similar to those of S2, with U- to V-shaped concave-up features, that usually does not exceed 8 m of relief (Figures 5 and 6). However, they reach c. 13 m of relief toward the Malamocco Inlet, in the seaward part of the SH312 seismic profile (Figure 5b). In the SH312 seismic profile, the concave-up features are locally associated to form composite structures of 0.5–1 km wide (Figure 5b). Although the concave-up features related to S3 in general developed in different positions with respect to those related to the underlying stratal surfaces; in some cases, they are found just above to those of S2, and less commonly to those of S1 (Figures 5 and 6). The flatter, near horizontal tracts of S3 are located between c. 1 and 2.5 m below the lagoon floor (Figures 5 and 6). S3 may truncate S2 and even S1, in which case, it represents the local boundary between the late-Pleistocene and Holocene deposits (Figures 5b and 6b).