Grey Cascade

Heringen, Germany

This mountain of potassium-mining waste salt stands 200 meters above the forests and farms around it and has polluted the nearby Werra River so that most freshwater plants and animals cannot survive there. Only plants that can tolerate high salinity can grow in the soil surrounding the mountain. The potassium mine that produces it has been in operation since 1976. As of January 2014, it covered 93 hectares (230 acres) and contained approximately 188 million tons of salt, with another 900 tons being added every hour, or 6.4 million tons per year.