The CEREMA (Center for studies and expertise on risks, the environment, mobility, and planning) and the DDTM (Departmental Directorate for Territories and the Sea) closely monitor the erosion of the 80 miles (130 km) of the Côte d'Albâtre (Alabaster Coast). The course of the GR21, which follows the cliffs, had to be modified as it stood too close to the edge after rockslides. The study of old documents and photos such as staff maps from the 2nd World War, postcards from the beginning of the century, and even paintings by artists are all indicators that allow predicting the dangers for the populations living on the cliffs.