IV.—Report on the Drift at Moel Tryfaen

Abstract

In August, 1898, it became known that what is perhaps the clearest and most instructive section in the famous high-level drift deposits at Moel Tryfaen must in a short time be swept away in the course of the quarrying operations. There are two slate quarries on Moel Tryfaen, the “Alexandra” and the “Moel Tryfaen” Quarries, excavated in the same line of strike of the slates. Gradually expanding, they had approached each other so nearly as to leave a narrow bank between them with no more than a yard or two of uncut turf upon it. Now the drift sections thus in danger of destruction are exceedingly important for the following reasons: (1) They are at right angles to the strike of the slates, and thus display the character of the underlying rock surface; (2) they show the nature and position of the junction of the shelly sands and gravels with the overlying Boulder-clay; (3) the false bedding and other structures in the sands and gravels are best seen along them; (4) they have been more accessible than the other sections in the quarries. A Committee was therefore appointed to preserve, by photography, supplemented by a written report, an impartial record of the phenomena displayed in these sections. The Committee have much pleasure in acknowledging their obligations to Mr. Menzies, the manager of the Alexandra Quarry, who, with a large-minded appreciation of scientific work for which geologists cannot be too grateful, offered to suspend operations in that part of the quarry for three months, besides showing the Committee every hospitality and facilitating their work by all means in his power.