This volume contains 16 papers that all deal with the Refrath 1 Borehole. This borehole is located in the Bergisch Gladbach-Paffrath Syncline (Ardennes-Rhenish Massif, Germany) specifically to study the poorly known Upper Devonian (Famennian) sediments. The borehole was funded by the Geological Survey of North Rhine-Westphalia. Although the initial emphasis was on the regional geology and the geological mapping, the discovery in the borehole of many different fossil groups initiated research on palaeontology and biostratigraphy together with sedimentology, facies, thermal maturity and organic geochemistry. Hence, this volume on the Refrath 1 Borehole clearly demonstrates how a seemingly routine Geological Survey NRW geological and engineering geological mapping project triggered a multi-disciplinary research project whose results are of international interest.