IV.—Pebble Ridges

Extract

As a contribution to our knowledge of the formation of these very interesting “natural embankments of the sea,” I may point to a little bay in Anglesea, immediately westward of the Bryn Ddu Limestone quarries on the north-east coast of Anglesea, about two miles and a half westward of Puffin Island. This little bay is not more than about a furlong across, and may be roughly described as semicircular in form, lying nearly due west to east from point to point. From being in miniature as it were, the ridge can be readily studied, and it is very striking to see how, commencing in the westward as a beach, it gradually rises into a ridge having very steep sides. No less remarkable is the way in which the stones increase in size as the ridge does in height. At the west end it may be described as composed of Limestone pebbles, with here and there a boulder, while at the east end it is built up almost entirely of large limestone boulders and blocks, many containing from one to two cubic feet and some more. Intermixed there are boulders from the size of the closed hand and upwards. The larger blocks are sub-angular and rounded, and no doubt get gradually worn down smaller and rounder, until they become “boulders.” by being moved about, by the sea; but some on the other hand, being thrown over on to the back of the bank, cannot be further affected by the waves. In this ridge, as I have pointed out is the case with the Chesil Bank, the stones follow the law of the bank itself, the largest being collected to form the highest part of the bank, which in both occurs where the wave-action is most intense.