THE LAKES OF SNOWDONIA AND EASTERN CARNARVONSHIRE. 429 



point on the margin of the lake, the bare rock rises clear of the thin covering of drift 

 lying on the slope of the Gribbin, along the south-east margin of the lake. 



FlG. 1. — Sections of Glaslyn. The black portion shows the true slopes ; the outline shows the slopes exaggerated 

 ten times. A-B, longitudinal ; C-D, cross section. 



Three sections are shown (Plate VIII.) : a longitudinal section A-B, and two cross 

 sections C-D and E-F. They serve to make clear that the waters of Glaslyn lie in a 

 deep basin-shaped hollow, about twice as long as it is broad, with sides steeply sloping, 

 especially from the western and southern margins. The great basin-like depression is 

 seen not to extend into the bay, and it terminates some distance away from the exit at 

 the narrow end of the lake. Nearly 20 per cent, of the total area lies within the 100 

 feet contour-line; one half of the total area is within the GO feet line, and only 15'7 

 per cent, of the area corresponds to depths below 20 feet. 



4. The Lakes of Llanberis. — The two lakes — Llyn Padarn and Llyn Peris — lie at 

 the foot of the well-known Pass of Llanberis. The Pass is a long narrow valley or 

 glen, wild and stony in aspect, running from south-east to north-west, and bounded on 

 both sides by some of the loftiest mountains in Wales. On the left or south-west the 

 great mass of Snowdon rises to a height of 3570 feet above sea-level, and its two pre- 

 cipitous shoulders, Crib Goch and Llechog, immediately overhang the Pass ; on the 

 right, tower Y Glyder Fawr, Y Garn, and Elidyr Fawr — all of which attain heights of 

 over 3000 feet. 



Down the Pass rushes a brawling stream bearing the name of Afon Nant Peris, 

 and, after a course of about four miles, during which it is joined by tributary 

 streamlets coming down from Cwm Glas and Cwm Glas-bach on the left and from the 

 slopes of Y Glyder on the right, it enters an alluvial stretch at Gwastad-Nant, and a 

 little short of a mile lower down loses itself in Llyn Peris. During its course along the 

 alluvial flat, it is joined by two streamlets from the right, one issuing from Cwm-gafar, 

 and the other from Cwm Dudodyn, the latter joining the main stream just above its 

 entrance into the lake. 



Llyn Peris is over a mile in length, and trends in the same direction as the Pass. 

 The slopes of Elidyr Fawr come down rather steeply to the right margin, and Pen 

 Careg-y-Fran towers up from the left. From its lower end a stream called Afon-y- 

 Bala makes its way over a flat strip of ground, about a quarter of a mile in length, to 

 Llyn Padarn. Llyn Padarn, the axis of which keeps in the same direction as that of 

 Peris, is two miles long, and from its lower end the river Seiont escapes to make its 

 way over undulating and drift-covered lowlands to the Menai Straits. 



