The Rhætic and Contiguous Deposits of Glamorganshire

Abstract

I. I ntroduction . I n the autumn of 1904 I made, in company with my friend, Mr. E. Talbot Paris, a detailed examination of the Rhætic and contiguous deposits of Monmouthshire and GLamorganshire. The results of my investigations in the former country have already been made known, and it now remains to record those in the latter. Less than four years have elapsed since the officers of the Geological Survey completed the re-survey of the Secondary rocks of Glamorganshire; and that part of the memoir on ‘The South-Wales Coalfield ’ which deals with the Bridgend district was only issued to the public last January. This being the case, it might be thought that but little of interest would have remained to be noticed in the present communication. However, whereas the officers of the Survey were mainly concerned in the mapping of the deposits, my attention was directed ill most cases to the accumulation of facts bearing upon the physical geography of the Rhætic Epoch. On a previous occasion I communicated to this Society a theory, to account for the geographical distribution in North-West Gloucestershire and Worcestershire of certain beds at the base of the Rhætic Series. I then stated that, ‘there is evidence to suggest that there were earth-pressures at work at the close of the Keuper Epoch, which caused the deposits to be thrown into slight synclinal and anticlinal flexures. In the depressed areas the earlier deposits of the Rhætic were laid down, and successive overlap on to the marls seems