462 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



belief that even where this view of the origin of the bosses does 

 not apply, he believes that sub -marine, and not glacial, action 

 must be referred to, since many of the rounded rocks possess fea- 

 tures which render it extremely unlikely that they could have 

 been rounded by glaciers, while others are so circumstanced that 

 it would seem to have been absolutely impossible. 



2. Fluted and striated Surfaces. — Having shown that the 

 rounding of rocks was in all probability not effected by glacial 

 action in North Wales, the author proceeds to show that the fluted 

 and striated appearances, also referred to the passage of large 

 bodies of ice, are really due to other causes ; and he first considers 

 an example referred to by Dr. Buckland, and situated about 100 

 yards below the bridge of Pont-aber-Glasslyn, near Bedd-Gelert, on 

 the right bank of the river. 



At this spot the rocks are rounded and polished, and covered 

 by flutings and striae generally parallel to the course of the valley; 

 but the author observes that such is not always the case, some of 

 the striae being very oblique, and some actually opposed to this 

 direction. 



The flutings in the instance now under consideration are also 

 considered to be more regular, more accurately parallel, and 

 more symmetrically placed than could be the case had they been 

 produced by the passage of a glacier. These flutings in the 

 Snowdonian schists rarely vary in any perceptible degree on the 

 same surface ; there is little or no distinguishable difference in 

 their depths or breadths ; and however numerous the lines, they 

 are uniformly and strictly parallel. They are also at equal dis- 

 tances from each other, and are so similar in different valleys that 

 the resemblance is striking. Phenomena of such a kind must, it 

 is concluded, be structural ; and the author believes that not only 

 do the furrows but also the striae — which are not parallel, but 

 more or less oblique and irregular — owe their existence to the 

 internal structure of the rocks. 



The flutings and striae of the rocks in the valley of the Llugwy 

 between Pont-y-Gy fling and Capel Curig, described by Dr. Buck- 

 land, are next alluded to. In this case the fluted lines on some of 

 the rocks on the Bangor or western side of the large dome-shaped 

 masses mentioned by Dr. Buckland, are stated to be in actual op- 

 position to the direction of the valley, although such flutings agree 

 in all their characters with others in the direction of the valley, 

 being parallel to one another, equi-distant, and as nearly as pos- 

 sible of the same width and depth. That these flutings are natural 

 furrows, and not due to glacial action, the following facts are then 

 adduced by the author as sufficient proofs. 



In the first place it is stated that close to the large dome-shaped 

 masses at about 200 yards from their western base, nearly opposite 

 the road which leads to Capel Curig, there are certain low rounded 

 rocks or bosses marked with furrows at right angles to one another, 

 and that the same occurs on a small mass of schist about midway 

 on the north side of the lower Llanberis Lake. These rocks also 



