On the Geology of the neighbourhood of Tremadoc, Caernarvonshire

Abstract

The little town of Tremadoc (in the northern part of Cardigan Bay) is beautifully situated on the north side of a valley formerly covered by the sea. Mr. Maddock having in the year 1813 made an embankment across the wider valley of Traeth Mawr, of which, on the western side, the Tremadoc valley was an inlet, the sea was barred out, the valley brought under cultivation, and the town erected. On approaching this district of Caernarvonshire from the east, it does not require the eye of a geologist to be assured that the sea once, and at a comparatively recent period, extended many miles inland. The succession of cliffs with steep escarpments facing the present line of coast, and extending inland up the eastern side of Traeth Mawr, one behind the other, for several miles, are striking features in the scenery of this romantic neighbourhood. the stratified rocks of the district have a general strike from north-west to south-east, with a north-east dip. They consist of slates, shales, flags and sandstones, but, from the almost total absence of organic remains, the determination of the age of the beds must be a work of considerable diffuculty and time, and is one in which great caution is requisite, for all these rocks have apparently undergone great change of structure in many places, and that which is the same formation or bed, presented under a new aspect, may be easily mistaken for a totally distinct deposit. Although some of the rocks are described