Title page dated 1843; date 1844 accepted by Sherborn, but volume not published before 1845. There is an offprint with additional plates published in parts between 1845 and 1846. See Anderson, 1964, Fortschritte in der Geologie von Rheinland und Westfalen, 14: 121.
Title page dated 1843 but not published until 1845. Reprinted 1845-1846 in book form with 33 additional plates