Alsace

Alsace is a region along the Rhine valley, where the locals traditionally speak Alsatian, or actually Alemannish, which is the German dialect spoken in Switzerland and in the German Black Forest. So this Alemannic cultural region actually covers three different countries. And during the 19th and the early 20th century France and Germany made multiple wars about the ownership of the region. So it belonged for some time to one country, then for some time to the other. This ended with World War II, when the region was occupied by the French once again. Today French is the official language, which is spoken with a local dialect, but at home people still speak Alsatian.

The geology is similar to the Black Forest: the two areas were uplifted while the mesozoic sedimentary rock was eroded. As a result all those rocks are gone and the crystalline basement is now on the surface. Crystalline rocks are not soluble so there is no karst and thus no caves, the area has numerous ores though, mostly hydrothermal deposits in dykes or gangues. So there is a wide range of show mines, and also numerous subterranea which were built mostly for military purposes. The part of the Rhine valley between the crystalline hills and the Rhine river also belongs to this area. This is a graben structure which was down-lifted and then filled with sedimentary rocks. There are now limestone layers covered by loose river sediments, but the surface is flat and about the level of the river, there is no underground drainage. The few caves are at the rim, where the uplift was smaller, and the limestone did not erode completely, but is still higher than the flat valley floor. Those caves are rare and small.