The Geology of the Country around Fishguard, Pembrokeshire

Abstract

On the northern coast of Pembrokeshire there lies a district of considerable area which has not been geologically investigated since the completion of the Government Survey under De la Beche in South Wales. The region adjoining that to be described in this paper has been made known to us in detail by the labours of Dr. Henry Hicks and others during the last few decades; and we may therefore claim a fairly complete acquaintance with the Archæan, Cambrian, and Ordovician rocks of South-west Pembrokeshire. North-east of a line running from Penclegyr Point on the coast inland to St. Elvis in the south, we have had, however, to confess comparative ignorance. The Geological Survey memoir on South Wales pays scant attention to this district, and relatively little information of importance can be obtained from any subsequent geological literature. My object in visiting this tract of country was to determine the age of the volcanic series indicated on the Survey map near the coast, and to investigate the characters of both the contemporaneous and intrusive igneous rocks in the field and laboratory. To petrological questions, therefore, special attention has been paid. The area with which this communication deals extends from Newport in the east to the western side of Strumble Head in the west, and lies north of a line drawn from Pwll Crochan to Cilgwyn, and passing through St. Nicholas and Llanllawer. This narrow strip of country, it will be noted, approximately coincides with the strike of the beds. (See Map,