404 W. A. Br end — Lakes of Caernarvonshire. 



One result of this was the breaking up of some of the surface 

 ci'ystalline beds of Central Sweden, and probably also of Finland, 

 into a mass of angular debris ; but this is only one lesson. The other 

 lesson, which seems as plain as Belshazzar's message, is, that this 

 violent and spasmodic upheaval of the bed of the gi-eat North Sea 

 caused it to shed its waters in violent and overwhelming force in all 

 directions, and thus brought about the phenomena which have been 

 such a puzzle and a paradox to the orthodox followers of Hutton and 

 of Lyell, who, like all disciples, have utterly exaggerated the teaching 

 of their masters. This is not ray conclusion only. I am only the devoted 

 scholar of much greater men, and among them of the greatest 

 geologist we ever produced in this country, which means the 

 greatest geologist of all time — Murchison — who stands out among 

 most of our contemporary lights like the Eddystone lighthouse 

 would if transplanted among the gas-lamps of Piccadilly. He had 

 the courage to speak out his real convictions, and I can only say 

 Amen. 



IV. — Notes on some of the Lakes of Caernarvonshire. 

 By W. A. Brend, B.A., B.Sc, F.G.S. 



SINCE the publication of Mr. Marr's numerous papers on the 

 tarns and lakes of the English Lake District, considerable 

 attention has been paid to the manner of formation of lake-basins in 

 the glaciated regions of Britain ; a few notes therefore on some of 

 the lakes of North Wales may not be without interest. 



At the head of the Nant Ffrancon Valley, between the range of 

 the Glyders and Carnedd Dafydd, are situated about half a dozen 

 small tarns. The largest of these, Llyn Ogwen, exhibits several 

 features of interest. Eock in situ can be traced all but continuously 

 round the lake. The exit is over rock ; on the north side Craig 

 Dhu and Craig-yr-Yrfa slope steeply vip to over 3,000 feet; on the 

 south are Tryfan and the Glyders. An alluvial flat extends back 

 from the head of the lake for about half a mile ; this is completely 

 rock-bound except for an interval about 40 yards wide just north of 

 Pont Bodesi. The ground here is about 30 feet above the surface of 

 the lake, and is flat and marshy, so that it is impossible to determine 

 whether solid rock or drift material lies beneath the surface. The 

 watershed between the Dena and the Llugwy is about a quarter of 

 a mile further east, and consists of a mass of drift. The extreme 

 shallowness of the lake is remarkable, and rather tends to increase 

 the probability of a drift dam at the point described above. 

 Soundings showed a depth of from 5 to 6 feet at the narrow end, 

 shelving gradually to about 8 feet in the widest part, and then 

 sloping upwards, rather more rapidly, towards the eastern 

 boundary of the lake. 



To the south-west of Ogwen, deep set amid frowning precipices, 

 lies Llyn Ldwal, one of the wildest tarns of Wales. Eamsay 

 describes it as being partly dammed up by a terminal moraine, but 



