Schopfheim (German pronunciation: [ˈʃɔpfhaɪm] ) is a town in the district of Lörrach in Baden-Württemberg, Germany. It is situated on the river Wiese, 10 km north of Rheinfelden, and 13 km east of Lörrach.
The town is the birthplace of Gisela Oeri, Max Picard, and Arno Villringer.
Karst lakes are formed as the result of a collapse of caves, especially in water-soluble rocks such as limestone, gypsum and dolomite. This process is known as karstification. They can cover areas of several hundred square kilometres. Their shallow lakebed is usually an insoluble layer of sediment so that water is impounded, leading to the formation of lakes. Many karst lakes only exist periodically, but return regularly after heavy rainfall.