The "Adorfer Klippe"

Directly on the road from Diemelsee-Adorf to Marsberg-Giershagen, the approximately 8-meter-high Martenberg Cliff is in a former open pit iron ore mine. Its geological structure comprises a sill profile of Middle to Upper Devonian rocks of the Givet, Adorf and Nehden stages, strongly reduced in thickness. Especially the limestones of the Givet and Adorf steps are rich in fossils. Their rich red iron fauna consists of cephalopods (cephalopods), brachiopods (arthropods), trilobites (three-lobed crustaceans), crinoids (crinoids), conodonts, and solitary corals.

The interest of paleontologists and stratigraphers in the Martenberg was aroused very early. At the beginning of the 20th century the term "Adorf Stage" was coined for the first time, the Martenberg cliff subsequently became type locality and guideline profile for the stratigraphic division of the Devonian and cradle of the worldwide valid cephalopod stratigraphy.