North Wales. 421 



Swiss moraines. Some of the loose stones are scratched, 

 the lines crossing each other confusedly ; and the mass 

 of the moraine is formed of three or four concentric 

 elliptical mounds, which merge together at their bases, 

 and mark on a small scale the gradual decrease of the 

 Cwm-glas glacier. These circle round the lower side of 

 a large roche moutonnee, which forms a small hill, as 

 shown in front of the cliff in the middle of fig. 87. 



A little behind this hill, about half a mile south of 

 Blaen-y-nant, a perfectly symmetrical terminal mo- 

 raine, grass-grown, but strewn with travelled blocks, 

 ranges across the valley between two brooks, almost as 

 regular in form as an artificial earthwork. It is be- 

 tween 1,200 and 1,300 feet above the sea. Higher up,, 

 on the west side of Cwm-glas, the striae on the rocks run 

 NNE. below the space where the glacier, in a cataract 

 of ice, once slid down the cliff that now appears so 

 grim. Four white threads of water glance on its side, 

 the sole representatives, in another form, of the jagged 

 ice-fall, that on a smaller scale must have resembled 

 the ice-cataract of the glacier of the Rhone. Beyond 

 this cliff, in one of the innermost recesses of Snowdon, 

 lies an upland valley bounded on three sides by tall 

 cliffs, in the midst of which lie two small, deep, clear 

 tarns about 2,200 feet above the sea, each in a perfect 

 basin of rock. Between these pools and the cliff below, 

 a large quantity of moraine-debris, derived from Crib- 

 goch, cumbers the ground. The rocks on which it lies 

 are often perfectly smoothed, rounded, and deeply 

 grooved; and the striae that, lower down the valley, 

 strike straight towards the Pass, here branch to the 

 south-west and south-east, following the courses of two 

 minor valleys on either side of a peaked ridge that 

 descends from Crig-goch to the ground between the 



