Large-scale primary sedimentary structures. Large sedimentary structures occur occasionally in the upper parts of the Gara Sbaa Formation and the lower parts of the Douira Formation. In contrast to the primarily sandstone unit in (A), the lithology of (B) consists of inter-bedded sandstone and finer-grained beds. Human for scale in each equals 185 cm. The large-scale cross-bedding with good bottomsets and relatively low angle foresets is consistent with small Gilbert-type delta fronts. Alternatively, they could represent large point bar deposition with the differing lithologies of B as inclined heterolithic stratification.