The present fourth, completely revised edition of the Geology of the Eifel describes the geological development of the Eifel region. In no other area of Germany is young volcanism more evident. The new edition includes the results of research conducted since the publication of the third edition in 1994. The author provides a detailed description of the stratigraphy of the Cambrian/Ordovician succession of the Eifel and the High Venn, as well as the subsequent younger deposits up to the Quaternary. Nomenclature and classification follow, particularly important in the Middle Devonian, the Permotrias, and in the Tertiary according to the latest stratigraphic classification. On this stratigraphic stack, the volcanoes and maars of the Eifel developed during the Tertiary and Quaternary. The depositional conditions in the Lower Devonian have been reconstructed more accurately, and numerous new age determinations have been carried out on both Tertiary and other deposits.