Reduction and related phenomena in the New Red Sandstone of south-west England

This report gives an account of the geological setting of reduction features in New Red Sandstone sediments from the area around Exmouth and Budleigh Salterton in south-west England, along with a review of the state of research and investigation into these phenomena. The abundance and significance of the commonest reduction phenomena (green spherical spots) are assessed, together with geochemical and mineralogical data from recent investigations on nodule material. The lack of identifiable fossil material within the Aylesbeare Mudstone suggests that the hypothesis that the formation of reduction spots and nodules is dependent upon the presence of organic matter is neither adequate nor appropriate for the occurrences in this area. Earlier investigations had identified in some of the nodules, carbon-containing substances, the origin of which was not clear; the possible relationship of this material to the formation of the reduction features is considered.