Within the framework of an archaeological project, a drilling core in the Nahr-El-Jaouz River Valley was taken in 2022 to reconstruct the palaeoenvironmental conditions. Sampling comprised more than 100 samples. Sedimentological techniques using grain size distributions and textural parameters were applied to assess the facies type and the conditions of sediment transport and deposition. At the base (10.50–10.00 m), gravelly-muddy sediments occur, representing a deltaic foreset followed by an alternating sequence of muds and sandy muds deposited directly at the river mouth or somewhat upstream (deltaic topset). The section above (10.00–9.35 m) consisting of sandy to muddy sediments indicates a transition between a lagoonal environment of the deltaic topset and a distal floodplain far from the main river. Most of the upper core (9.35 m to the surface) presents mainly muddy and sandy wetland deposits. Frequent facial changes from distal to proximate floodplain positions can be observed. Gravelly layers occur as occasional intercalations deposited by more turbulent floods of different reach and force. The drill core indicates a former sea arm of a several kilometers long Nahr-El-Jaouz River mouth. Unfortunately, no age data from 14C analyses of taken charcoals or from OSL dating are available. Depending on these results, different conclusions regarding the development of historic landscapes and the archaeological interpretation of human economics and settlements since the Bronze Age will be possible.