The boundary between the Devonian and the Carboniferous has been drawn using ammonoids, conodonts and miospores, while geochemical data have only rarely been used. The sampling of eight sections (Aprath, Apricke, Effenberg, Wocklum, Stockum, Drewer WJ, Drewer WA, Marsberg) at the northern margin of the Rhenish Mountains demonstrates the potential of the isotope ratio of organic carbon to regionally correlate sections in different facies areas. With the help of the carbon isotopes, a distinct stratigraphic succession is documented, which is characterised by several positive and negative excursions; this succession was recorded in all examined sections. The carbon isotopes can therefore make a significant contribution to the stratigraphic subdivision of sections and complement the biostratigraphic methods.
