Article: Further studies on micro-organisms and the presence of syngenetic pyrite

Various microscopic pyrite forms are described from Lower Jurassic and Carboniferous argillaceous rocks and it is confirmed that solution of the pyrite reveals abundant microfossils of a limited range of morphological variety which are described and figured. Two groups are distinguished, one showing clear association with plant material and the other with animal remains. Of the latter, occurrences of later geological and Recent ages are briefly noted and figured. Both forms were probably of a saprophytic nature and are thought to have been involved in the production of hydrogen sulphide and, consequently, the precipitation of the iron sulphide with which they are now found. The environment of this activity is discussed with particular reference to the Liassic deposits studied. No stratigraphic distinction is found for the microfossils within the inclusive period from Lower Carboniferous to Lower Jurassic.