Seafloor character of the Roman Rock area in False Bay, South Africa

Context: This study investigates the seafloor character of a 12 km2 area off Simon’s Town in False Bay, South Africa. Aims: The goal was to map the seafloor geology around Roman Rock Lighthouse, focusing on sedimentology. Methods: Side-scan sonar and single-beam echosounder were used, complemented by sediment sampling and diver observations for ground-truthing. Sediment samples were analysed for texture and composition. Key Results: Six patterns of reflectivity (acoustic facies) were identified, including granite outcrops, wave ripples, and patches of gravelly and quartzose sands. Sediment analysis showed a mix of calcareous and quartzose components, with calcareous material dominating the gravel fraction near granite outcrops. Conclusions: The Roman Rock seafloor reflects a complex depositional environment shaped by biogenic activity and wave-induced sediment transport. Implications: This research lays the groundwork for future geological studies in False Bay, particularly around wave-induced sediment dynamics.