Source: Pascal Brackman
Rocks near the shoreline have frequently the characteristic of containing potholes. These potholes are shallow, almost perfect circular depressions of a few centimeters to a few tens of centimeters. In these potholes, salt seawater is collected during storms. But when there is a long calm and hot period such as during the summer, the water evaporates and leaves a crust of pure white salt behind. Many locals collect this salt.