Welsh Journals

THE Higher SILURIAN ROCKS OF THE KERRY DISTRICT, Montgomeryshire. By J. R. Earp, M.Sc. Quarterly Journal Geological Society of London, vol. xciv, 1938. The attention of members is drawn to a recent account of the geology of the country around and to the south of Kerry. This work has been carried out by Mr. J. R. Earp, a student in the University of Manchester and is published in the Quarterly Journal of the Geological Society of London. A separate copy of the paper has been presented to the Powysland Club and is available for reference in its library. No detailed investigations have been carried out in this part of the Clun Forest country since the early half of the nineteenth century. Murchison gave a general description in 1839 and the most recent Geological Survey map dates from 1850. Since then much work has been done elsewhere in Britain on the Silurian rocks and this paper gives a full account of the rocks and fossils in this part of the Welsh Borderland. The rocks of Kerry belong to the upper part of the Silurian system, namely, the Ludlovian and Downtonian. The Ludlovian consists of more than 5,000 feet of shales and mudstones which have been subdivided into various groups based principally upon the fossils which they contain. They pass upwards into Down- tonian rocks of which about 1,000 feet have been examined. These younger rocks are more varied in character and the red colouration of much of them distinguishes them from the other rocks in the district. The paper includes a list of the various fossils, graptolites, brachiopods, molluscs, etc., which have been collected. The characters of the rocks are described in considerable detail as well as the localities where they may be studied. A large geological map shows the distribution of the various rock groups and thus reveals their structural arrange- ment. We may mention that the familiar walk from Kerry to the Anchor by the path from Dafern to Pant-y-llidiart and the road to Kerry Pole crosses over many of the groups, while the abundantly fossiliferous Platyschisma Beds which define the boundary between the Ludlovian and Downtonian appear in the stream just north of Castell Bryn Amlwg, as well as in a roadside quarry west cf Crossways and about a mile and a half east of Anchor. Examination of the geological map will reveal many other places where the rocks may be seen and fossils collected. The paper is also noteworthy for the account given of the remarkable rocks which are seen in the south-western part of the district. The normal Ludlovian rocks consist of well-bedded shales and siltstones which were deposited as thin horizontal layers of mud and silt on the floor of the Silurian sea. The layers are usually quite distinct and parallel to one another giving a characteristically banded appearance, although in any given exposure the beds may be tilted now owing to the earth-movements which they have experienced since they were deposited. South-west of Kerry, these Ludlovian rocks also include bands of varying thickness in which the muddy and silty layers are most highly distorted and show very complicated folds and contortions. These layers of contorted rocks are thus included between beds which are normally bedded. Such contorted beds occupy