396 Mackintosh — On the Cliffs andValleys of Wales. 



Valleys and Cliffs near Llangollen. — On entering the old bay of the 

 Mnrchisonian, or Severn Sea, now called the Vale of Llangollen, 

 the river trick, or denudation puzzle, again presents itself, and is 

 repeated as far up as Corwen.' But in whatever way the directly or ob- 

 liquely-transverse valleys, and their connecting gorges, may have been 

 formed, it is very obvious that the sea must have been here at no very 

 distant period, geologically speaking. There is a true marine strait, 

 or mountain pass, at a considerable altitude behind Barber's Hill.^ 

 The footpath from Llangollen to Try-Carreg Farm leads through it. 

 At both ends the ground rapidly declines, and no freshwater stream 

 could ever have traversed it. The rocks on the south side present 

 indications of sea-action. It may have been formed, or, at least, 

 m;odified, during the glacial submergence. The Eglwyseg range of 

 cliffs on the opposite side of the irregular Vale of Llangollen are,, 

 in some parts, a fac-simile of cliffs now or lately washed by the 

 waves at Llandudno. There are seven rounded promontories, with 

 six intervening inlets. Of the latter, four are dry, and two are- 

 traversed by insignificant streams. It would be going too far to 

 assert that the successive terraces mark as many pauses during the rise 

 of the land above the sea. But that they have been carved out by 

 a great body of water appears evident not only from the general con- 

 figuration, but from features already referred to (page 391).^ 



Bemarhahle Assemblage of Baised Beaches. — To the south-west of 

 Llangollen I met with the most extensive and perfect series of raised 

 beaches I have yet seen in South Britain. They commence on the 

 side of a hill about a mile to the South of Llantysilio railway station ; 

 and the stream which falls into the Dee, close to the station, interrupts 

 their continuity in the upper part of its course. They consist of main 

 and subsidiary terraces ; and as many as nine can easily be distin- 

 guished. The lower and more striking terraces, near Try-Carreg Farm, 

 are not now under cultivation, and from the circumstance of several 

 erratic boulders of trap lying on the platforms, one would suppose 

 they have never been cultivated. The upper terraces have evidently 

 been much effaced by the action of the plough. The cliffs of the 

 lower terraces are more or less rocky, and appearances justify the 

 behef that they have been undermined by the sea. The breadth of 

 the platform C (Plate XV. Fig. 13, which roughly represents a part 

 of these terraces as seen from a distance) I found to be about 150 



1 Between Llangollen and Corwen, on the left hand side of the road, streams with 

 cascades may be seen descending from the Berwyn Mountains, with little or no channel 

 to mark their course. Behind Corwen a powerful stream has, in some places, excavated 

 no channel at all, in other places a miniature gorge. The excavating power of this 

 stream is assisted by a steeply-inclined course, and numerous cascades; and the gorge 

 may, with the greatest safety, be regarded as the measure of its denuding capabilities, 

 as the ground on each side rather falls away from it than towards it. 



2 Fig. 12, Plate XV., is a distant view of this pass. In most of the wet passes of 

 "Wales and the Lake District, with which I am acquainted, the streams which flow 

 away from the cols could have had no share in the formation of the cols themselves, 

 which indicate an agency cutting straight through a ridge, and cannot be referred to 

 an improbable linear coincidence in the original soiirces of the streams. 



3 See Mr. Kinahaa's able article on raised beaches in Ireland, in Geol. Mag , 

 Aug., 1866. 



