Unit H1. Unit H1 is bounded below by S1 and above by S2, and shows strong thickness changes from c. 1 to 18 m due to the marked irregularity of the bounding surfaces (Figures 5 and 6). On average, the thickness is lower northward and landward (to the west; Figures 5b and 6a). Where S2 intercepts S1, Unit H1 is absent (Figures 5 and 6). The unit contains high- to lowamplitude reflectors that typically are parallel or show lowangle relationships with respect to the near horizontal intervals of S1, and can be oblique to sigmoidal, V- to U-shaped, or sinusoidal in the intervals characterized by the concave-up features of S1 (Figures 5 and 6). Near horizontal reflectors are locally found in the more squared concave-up features (Figure 6a and b). The occurrence of nested concave-up features indicates that the larger ones are composite (Figure 5a and b). In some tracts of the seismic profiles, especially below the modern tidal channels, the features of Unit 1 as well as S1 and S2 are not recognizable (Figures 5b and 6a and b)