AbstractThe Manx breccias, previously described as crush‐conglomerates of tectonic origin, are ascribed to sub‐aqueous sliding. The stratigraphical succession in the Manx Slates of the northern part of the Isle of Man is deduced, with the aid of the way‐up evidence provided by graded bedding and current bedding. The significance and position of fossils which Bolton claimed he found in the Manx Slates are reviewed and it is concluded that the specimens ofDictyonemaprobably came from the Isle of Man. The way‐up evidence indicates that the slate at the alleged fossil locality (Cronk Sumark) belongs to the youngest exposed division of the Manx Slates, so that other divisions are probably older then T