Tropical rock coasts: Cliff, notch and platform erosion dynamics

Rock coasts are widespread in the tropics and exhibit particular morphologies that may be specific to their tropical, micro-tidal location. Notches are particularly well developed, often linked to onshore cliffs and fronted by subhorizontal platforms. Through a review of previously published data across the tropics, average cliff face erosion rates are calculated as 2.15 ± 2.62 mm a^-1, intertidal erosion rates 3.03 ± 7.50 mm a^-1 and subtidal erosion rates 0.96 ± 0.44 mm a^-1. Intertidal erosion rates are variable within and across latitudinal ranges: within 10°N and S of the equator average rates are 1.42 ± 1.22 mm a^-1; between latitudes of 10°and 20°, 0.88 ± 1.16 mm a^-1 and between latitudes of 20°and 30°, 2.04 ± 2.57 mm a^-1. A consideration of temporal variations in intertidal erosion rates provides insights into the potential impacts of climate change on the erosion dynamics of rock coasts in the tropics. This paper highlights some of the interactions over time and space between process and measurement that continue to limit our understanding of, and ability to model, the erosion dynamics of tropical rock coasts. It concludes by identifying potentially fruitful areas for future research.