Tropical rock coasts: cliff, notch and platform erosion

Rock coasts are widespread in the tropics and exhibit particular morphologies specific to their tropical, micro-tidal location. Notches are particularly well developed, often linked to onshore cliffs and fronted by sub-horizontal platforms. Through a review of previously published data across the tropics, average cliff face erosion rates are calculated as 2.15 2.62 mm/yr, intertidal erosion rates 3.03 7.50 mm/yr and subtidal erosion rates 0.96 0.44 mm/yr. Within 100 intertidal erosion rates are calculated as 2.16 1.46 mm/yr, between 100 and 200 1.17 1.3 mm/yr and between 200 and 300 1.76 0.69 mm/yr. The calculations suggest that intertidal erosion rates on tropical rock coasts have almost halved since the mid-1970s, indicating a sensitivity to climate, and associated sea level, change. 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 dynamics of tropical rock coasts. It concludes by identifying fruitful areas for future research