The Bohlen is a rock face about 800 meters long and up to 100 meters high on the right bank of the Saale between Saalfeld and Obernitz. The predominantly naturally formed steep face is made up of Variscan folded and schistose marine Upper Devonian and Lower Carboniferous pelagic sediments, which are unconformably covered by horizontally bedded Zechstein limestones of the Tafelstockwerk. The outcrop is a classic site in terms of scientific history and a unique example of the Variscan unconformity in Central Europe. The strongly folded and tectonically repeatedly disturbed layer sequence of the basement, which is approx. 150 meters thick, represents typical basin sediments of the Devonian and Carboniferous in the Saxothuringian and can be regarded as a reference profile. Its wealth of fossils reflects important stages in the development of the geobiosphere and especially of marine life. The geological inventory found here documents important events in the Earth's history from 256 to 380 million years ago.