98 W. B. Wright — Preglacial Shoreline in the 



Now the preglacial shoreline of the southern half of the British 

 Isles has for some time past been fairly well known. Indeed, in the 

 districts outside the glaciated area it has been the subject of papers 

 from the very earliest days of geology, but its preglacial age was not 

 at first recognized. It was not until Mr. Lamplugh 1 in 1888 

 described the buried cliff and beach beneath the drifts of riamborough 

 Head in Yorkshire that the first clue in this direction was obtained. 

 Prom Yorkshire to the south coast of England, however, is a long 

 cry, and the correlation was not readily made. In 1900, however, 

 Mr. Tiddemau 2 showed that this shoreline of the south coast, which 

 had been found also along the shores of the Bristol Channel, could 

 be traced in South Wales beneath the boulder-clay, and he thus 

 clearly established its preglacial age. Mr. Lamplugh 3 next proved its 

 existence in the Isle of Man, and subsequently its presence was 

 established along the whole south coast of Ireland and up the east 

 coast as far as Dublin. 4 More recently it has been detected in Clare 

 by the present author, 8 and in Kilary Harbour, county Mayo, by 

 Messrs. Maufe & Carruthers. 6 Mr. Fearnsides 6 has also quite recently 

 proved it to occur in Carnarvonshire in North Wales. 



Thus it will he seen that in those portions of the British Isles lying 

 south of a line through Yorkshire, the Isle of Man, and Mayo we are 

 already well acquainted with the level of the preglacial sea, and it is 

 remarkable that this level is almost coincident with the present sea- 

 level. Throughout the greater part of this district it stands uniformly 

 some 10 or 12 feet above the present high- water mark, and maintains 

 a remarkable parallelism with the present shore. This parallelism 

 proves almost beyond a doubt that no marked permanent deformation 

 by folding or faulting has taken place over this wide area since pre- 

 glacial times. It would perhaps be safer to qualify this statement 

 somewhat and to say instead that if any such deformation has occurred 

 within the area it is entirely exceptional and local. We have, 

 however, no definite indication of any displacement of the kind, and, 

 even if such did occur, it cannot affect the conclusion that has just 

 been drawn regarding the general stability of the region. 



Now throughout this apparently stable district there occur 

 submerged forests and peat beds often at a considerable depth below 

 sea-level. The oscillation which allowed of their formation we must 

 therefore regard as temporary, at least in the sense that the sea has 



1 G. W. Lamplugh, "Report on the Buried Cliff at Sewerby " : Proc. 

 Yorkshire Geol. and Polytec. Soc, vol. ix, pp. 382-92, 1889, and Rep. Brit. 

 Assoc, for 1888. See also "Drifts of Flamborough Head " : Quart. Journ. Geol. 

 Soc, vol. xlvii, p. 394, and Proc. Yorks. Geol. and Polytec. Soc, vol. xv, 

 pp. 91-5, 1903. 



2 R. H. Tiddeman, " On the Age of the Baised Beach of Southern Britain as 

 seen in Gower " : Rep. Brit. Assoc, 1900, p. 760. 



3 G. W. Lamplugh, " Geology of the Isle of Man," p. 14 : Mem. Geol. Surv. 

 U.K., 1903. 



4 W. B. Wright & H. B. Muff (now Maufe), " The Pre-glacial Raised Beach of 

 the South Coast of Ireland": Sci. Proc. Roy. Dublin Soc, vol. x (n.S.), pt. ii, 

 p. 250, 1904. 



5 Descriptions not yet published. 



6 W. G. Fearnsides, " The Tremadoc Slates and Associated Rocks of Soutk- 

 East Carnarvonshire" : Quart. Journ. Geol. Soc, vol. lxvi, p. 182, 1910. 



