The Missing link between beach and clifftop dune – Landscape evolution of the climbing dune in the Feng-Chiue-Sha area of Hengchun Peninsula, Taiwan

Previous study by Ho et al. (2017) proposed an evolutionary model of the Feng-Chuie-Sha (FCS) clifftop dunes in the Hengchun Peninsula, southeastern Taiwan. In this model, tectonic uplifting, eustatic sea-level falling and the fluctuations of the East Asian winter Monsoon during the late Holocene could be the major forcing factors to the development of the clifftop dune. However, the climbing dune at the bottom of the cliff has not been carefully investigated yet, as the climbing dune is an important link between the beach and the clifftop dune, in terms of aeolian sediment cascades. In this study, we aim to improve our understanding of the unique beach-climbing dune-clifftop dune system in the FCS, and to identify phases of the changing influence of geomorphological forcing factors during the Holocene. For the paleo-environmental reconstruction, a detailed chronological framework will be established by applying numerical dating techniques, such as radiocarbon and optically stimulated luminescence (OSL) dating. Landscape features and sedimentological successions were mapped in the field and samples were taken for high resolution grain size analyses. Preliminary results show that several carbonate-cemented thin layers of aeolian sediment were observed in the outcrop. Based on the sedimentological sequence, the thin layers in two sections can be correlated well. We interpret the correlated thin layers as palaeo-surfaces of the climbing dune, and they may indicate the pause time of sand accumulation. The slopes of the palaeo-surfaces gradually increase from the bottom to the top, demonstrating the morphological development of the climbing dune over time. As the OSL and radiocarbon dates of the outcrop section are still under processing, the accumulation periods and rates of the climbing dune and its relationship with the formation of the clifftop dune will be presented and discussed.

Ho, L., Lüthgens, C., Wong, Y., Yen, J., Chyi, S.(2017): Late Holocene cliff-top dune evolution in the Hengchun Peninsula of Taiwan: Implications for palaeoenvironmental reconstruction. Journal of Asian Earth Sciences 148, 13-30.