584- Geological Society : Anniversaty Address, 1842. 



formed sets of parallel markings which he observed in the newly 

 uncovered surfaces of the schistose Silurian rocks, and shows satis- 

 factorily how such appearances, as well as the tops of the joints, 

 might be mistaken by cursory observers for scratches, although 

 they are in fact due to structure. 



Unlike Mr. Bowman, Dr. Buckland has not confined his views of 

 the action of glaciers to Scotland, but applies them largely to the 

 North of England and to Wales. He has recently endeavoured to 

 satisfy us, that tlie rocks on the sides of the chief valleys in the lat- 

 ter country which open out from a common centre of elevation are 

 striated, Avorn and polished in the direction of the present water- 

 courses, and these he conceives to be evidences of former glaciers, 

 which filled up all the valleys radiating from Snowdon to a distance 

 of many miles from a common centre. 1 confess I see almost insur- 

 mountable objections to this view. Apart from other evidence, the 

 very physical geography of this tract is at variance with the construc- 

 tion of such an hypothesis. In the Alps, and indeed in every other 

 part of the world in which they have been observed, the length of gla- 

 ciers is in ratio to the height of tlie mountains from which they ad- 

 vance, or, to use the words of Agassiz, from which they expand. 

 Now whilst in the present days, a small glacier hangs to the sides of 

 a mighty giant like Mont Blanc, having the altitude of 15,000 feet, 

 our Welch hills, having a height only of 4000 feet, had glaciers, by 

 the showing of Dr. Buckland, of a length of many miles. Again, in 

 the same memoir, which fills so large a portion of the principality 

 with glaciers, the author comments upon certain facts already well 

 known to us, viz. the existence upon Moel Tryfane and the adja- 

 cent W^elch mountains of sea shells of existing species, at heights of 

 1500 and 1700 feet above the sea, where they are associated with 

 mixed detritus of rocks transported from afar, all of Avhich have 

 travelled from the North, the hard chalk and flints of the North of 

 Ireland being included. How are we to reconcile these facts with 

 the theory that the greater part of the country in question was 

 frozen up under the atmosphere in some part of the same modern 

 period ? Unable otherwise to explain how marine shells should be 

 found on mountains which are supposed to have been previously 

 and during the same great period occupied by terrestrial glaciers 

 the accumulation of ages, Dr. Buckland invokes anew the aid of 

 the old hypothesis of a great wave. This wave, rolling from the 

 north, must Iiave dashed over the mountains to a height of near 

 2000 feet, depositing as it went gravel, boulders and fragments, 

 derived from places 200 miles distant, and transporting also marine 

 shells in its passage. But is it not more natural and accordant with 

 all the data upon which our science has been reared, to suppose that 

 when such shells were deposited, the parts of the mountains so 

 affected were permanently beneath the sea, than to call into play the 

 assumption of the passage of so mighty a wave ? At one moment 

 the argument used is, that scratches and polishings of rock must 

 have been done by ice, because in existing nature it has been found 

 that ice can produce such effects ; and in the same breath we are told 



