Origin of the Chesil Bank

Abstract

IN your report (vol. xi. p. 299) of the paper on this subject by Prof. Prestwich, read at the Institution of Civil Engineers, are these words:—“The large dimensions of the bank he attributed to the great accumulative and small lateral action of the waves.” Why, then, does not so general a cause form hundreds of such banks? Why is “the great accumulative action of the waves” confined solely to the Chesil Bank, and particularly to the Portland end of it? Because the travelling of the pebbles is towards Portland, which checks the travelling, and so allows of “accumulation” exactly as a groin does. This is the simple “open sesame” of the secret; and if we could build groins as large as Portland, every one of them would “accumulate” a bank of precisely the same conditions as the Chesil Bank. If the pebbles travelled from Portland, as the professor thinks, that end of the bank should be the lowest; it would be perpetually robbed by the waves. But it is the highest—forty-three feet; and the Abbotsbury end, to which he supposes the pebbles to travel, should be the highest, but it is the lowest—scarcely more than half the height, twenty-three feet; while at Bridport there should be a still higher bank, for the professor makes the pebbles travel from east to west there and meet the pebbles which had “travelled from the opposite direction, viz., from west to east” But at Bridport there is not a single pebble, but only blown sand.