Societies and Academies

Abstract

LONDON.Geological Society, February 7.—Prof. W. W. Watts, F.R.S., president, in the chair.—Dr. A. H. Cox: An inlier of Longmyndian and Cambrian at Pedwardine (Herefordshire). The inlier comprises a strip of country about a mile in length and half a mile in breadth, situated near the border of Herefordshire and Radnorshire, about fifteen miles south of Church Stretton. Wenlock and Ludlow beds occupy most of the area around Pedwardine, but the occurrence of Cambrian Shale yielding Dictyonema has long been known. The Dictyonema Shales dip steeply westwards towards a series of red and green conglomerates and grits, with which an occasional thin shale-band is interbedded. The latter beds, previously mapped as Llandovery, are here referred to the Longmyndian. They also dip westwards, and have suffered disturbance, accompanied by overthrusting from the west. They are un-fossiliferous, and neither on lithological nor on structural grounds can they be regarded as Llandovery strata resting unconformably upon the Cambrian. The grits at Pedwardine have apparently been carried south-eastwards over the Cambrian along an almost horizontal thrust-plane. There is also present a remnant of Bala grits, which dip gently eastwards, and rest with strong unconformity upon the Cambrian shales. The undisturbed character of these Bala beds suggests that the neighbouring thrust may be of pre-Bala date. Later faulting along a north-and-south line has brought the members of these older formations against Wenlock and Ludlow beds. From the disturbed character of the Silurian strata to the west of the inlier it would appear that this inlier is part of a barrier which has preserved the district lying to the east from the effects of the post-Silurian movements.