THE 



GEOLOGICAL MAGAZINE. 



No. XXV.— JULY, 1866. 



OK-IOID^J^^Xi -^E-TIOXiES. 



I. — On an Ancient Coast-line in Jsiorth Wales. 

 By Miss Eyton. 



THE Coast-line whicli I am about to describe extends from tbe 

 Vale of Clwyd, in Flintshire, to the Great Orme's-head 

 Mountain at the northern end of the Menai Straits. 



The Vale of Clwyd is an ancient bay or estuary some five or six 

 miles in width at the mouth, and narrowing gradually as it winds 

 inland. The hills on either side of the valley are low and rounded 

 at the summit, showing that they were once totally submerged. 

 Immediately above the present beach is a tract of reclaimed land, 

 composed of sea-sand, lightly coated in some parts with vegetable 

 earth, and containing nearly perfect remains of many recent shells. 

 On the neck of land which connects the Great Orme's-head with the 

 mainland of Carnarvonshire, I picked up tolerably perfect specimens 

 of Mytilus edulis, Cardium edide, Venus, and Patella vulgata, curiously 

 intermingled with the land shells Clausilia and Bidimus. 



Underlying the sand is a bed of Boulder-clay of uncertain depth, 

 thickly charged with small, round, scratched pebbles. This, so far 

 as I am aware, contains no organic remains. It is, in many parts, 

 closely perforated by Pholadce. On the Conway side of the neck 

 of land before alluded to, some good sections are exposed. I here 

 insert one. 



Vegetable earth, ' ... 



Sea-sand, 



Dark vegetable earth, 



Sand, 



Boulder-clay, charged with pebbles, about 



Thus, after each bed of soil had been formed by the gTowth and 

 decay of vegetable matter, it was covered by sand which drifted over 

 it from the beach. I may mention that the isthmus, situated as it is 

 between the two bays of Llandudno and Conway, is peculiarly 

 exposed to the influence of high winds. 



TOL, lU. — NO. SXV. 19 



