The glacial and post-glacial history of the lower Teifi valley

Abstract

Gorges in the lower Teifi valley formed short cuts towards the end of the Glacial period; former meandering pre-glacial courses were abandoned and are now filled to considerable depths, mainly by boulder-clay. Each gorge must have been eroded by a river flow greatly exceeding that of the present river, even in the highest floods. During the retreat of the ice from south-west Wales and the Irish Sea, the margin of the ice lay near the mouth of the Teifi just below Cardigan and thence probably ran nearly eastward along the northern slopes of the valley. A glacial lake was then impounded in the valley and overflowed by various channels, beginning at a level of 650 ft, at first into Carmarthen Bay and later into the Bristol Channel through Milford Haven. When the ice retreated to the mouth of the Teifi most of the lake then remaining was drained and river flow was resumed. At this time erosion of most of the gorges began.