466 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



to moraines. It is also observed that the physical structure of the 

 country round Pentre-Voelas is that of an open and widely ex- 

 tended plain, — Snowdon being twenty miles off, and there being 

 no height of any consequence much nearer ; so that it is impos- 

 sible to conjecture whence such enormous masses of ice could be 

 derived, or how they could have been urged forwards to dis- 

 tribute the detritus. 



The next instance alluded to is between Pont-y-Gyffing and 

 Capel Curig, and consists of a mound of gravel close above certain 

 dome-shaped hummocks, in front of the confluence of the upper 

 valley of the Llugwy with that of Nant-y-Gwyrd. In this case, 

 however, the author discovered, on examination, that what ap- 

 pears to be a mound of gravel is merely a low wavy ridge of 

 schist, whose ragged and weathered surfaces seem, at a little dis- 

 tance, as if covered with fragments ; although, in fact, they are 

 nearly bare. The author therefore believes that no such gravel 

 exists on the spot alluded to. 



Another of the supposed moraines referred to by Dr. Buckland 

 occurs near the elevated lake of the Flynnon Llugwy, north of the 

 road leading from Capel Curig to Bethesda. It consists of two 

 principal streams of blocks, one extending downwards in a S.W. 

 direction from near the lower end of the lake for about two miles 

 and a half; the other taking an opposite course, and reaching 

 partly across the upper end of the valley, a distance of nearly 

 half a mile. The former of these groups is marked by no glacial 

 feature, and is chiefly remarkable for its length and its general 

 conformity to the curves of the river ; but the latter or smaller 

 group exhibits at its further extremity four or five detached piles 

 of angular blocks about twenty feet in height. Near its point of 

 commencement also, on the west side of the valley, it passes over 

 two mounds, 20 or 30 feet high, covered with peat and herbage ; 

 and a similar mound, somewhat larger and higher, occurs at the 

 other end of the line, having also blocks upon its top. 



The author considers that the blocks forming this group have 

 descended from the mountain on the western side of the valley, 

 but that, since there are no rounded blocks and flat-sided pebbles, 

 such as are seen in Alpine glaciers, and indeed no traces of 

 glacial action, the deposit must have found its way from the 

 mountain, traversing a distance of nearly half a mile, and that some 

 of the blocks, after crossing the little stream of the Llugwy, have 

 ascended for perhaps 20 or 30 feet above it. This transit, it is 

 considered, may have been effected by the aid of snow and ice, 

 though not in the form of a glacier ; and in support of this view, 

 two occurrences are described bearing upon the point. One of 

 these took place in the winter of 1813-14, when drifted snow had 

 so accumulated in the course of several weeks near the mountain 

 stream called the Affon Bertham, in the valley of Nant Francon, 

 that it formed a deep broad sloping talus, above a quarter of a 

 mile in length, so compact that men and horses and fully-laden 

 carts frequently passed over it ; and the other, in the same valley, 



