Abrasion effectivity in rock coast potholes

The deepening and widening of a pothole is mainly attributed to abrasion by the rotatory movement of coarse sediments trapped inside. In rock coast potholes the effectivity of abrasion neds to be demonstrated. The upper section of a pothole wall is comparatively rougher than the rest and often displays a biological coverage. In the lower section, instead, abrasion reduces weathering effects and the rock is fresh and harder. We applied the durometers Equotip and Piccolo (Proceq©) in three potholes in the coast of Calafuria (Tuscany, Italy) to investigate the effectiveness of abrasion. We tested both devices using the Single and Repeated impact methods. The pothole was dried, the sediment inside removed, and the relative depth of each reading point was measured. Finally a sample of the gravel fraction from the sediment of the pothole was analyzed in the laboratory. The results confirm that both devices are suitable for measuring abrasion inside the potholes, and that the data recorded are comparable