The Rocks of Guernsey

Abstract

A t the opening of this paper I desire to acknowledge my great obligations to Professor Bonney for his assistance throughout my investigations. I must also thank J. R. Cousins, Esq., of St. John’s College, Cambridge, for valuable help. Little has hitherto been written on the geology of Guernsey which would be of much use to a visitor. Macculloch contributed a brief account to one of the earliest publications of this Society. Ansted’s book on the Channel Islands contains some remarks on its general features. There are two papers by Professor Liveing, with which in many respects I cannot agree, in the Cambr. Phil. Soc. Proc. vols. iii. and iv., and one by Mr. J. A. Birds in the Geol. Mag. for 1878, which contains some accurate observations. A few interesting but short papers on raised beaches and the like complete the literature of the subject. How scanty is the information furnished thereby may be imagined from the fact that not one of these publications contains a geological map; and the sketch map (Pl. XX.) which accompanies this paper is, so far as I know, the first which has ever been published. Any map shows clearly enough the triangular shape of Guernsey, and with a glance at the scale of miles its dimensions can be easily estimated. But most maps do not even attempt to indicate the remarkable physical difference between the northern and southern parts. A spectator on the deck of a steamer approaching St. Peter’s Port sees on the