on the Rocks in the Environs of Edinburgh. 307 



wears and striates it by means of the sand and gravel which 

 is interposed ;* and hence it is very clear that the hardest 

 rocks cannot resist a friction so completely overwhelming. 

 But on the other hand, when one has witnessed the floating 

 icebergs, the sport of the winds and waves, dancing upon the 

 surface of the sea, — when we have seen them stranded on 

 the shore, and rocking on themselves, — when we have noticed 

 them arrested by a trifling obstruction, we can scarcely be- 

 lieve that they ever possessed a power to wear away and 

 striate the rocks. It is true, however, that recourse is had 

 to the agency of currents w^hich are endowed with an extra- 

 ordinary velocity ; while, in a state of matters so nearly ap- 

 proaching to these how existing, and which still occur in the 

 Polar Seas, we cannot see how any one can venture to con- 

 tend for currents more rapid than those which now prevail. 

 As it regards the ocean, I am acquainted with only two facts 

 which bear on the action of floating icebergs ; the one re- 

 ported by M. Forchammer, who witnessed a very deep fur- 

 row traced on the humid argillaceous sand upon the coast of 

 Denmark. The fishermen declared that this furrow had been 

 produced by a block which had been wafted by the ice that 

 had been produced on the margin of the ocean. t The other 

 is that of striae produced on the rocks in the Bay of Fundy, 

 Nova Scotia, at the foot of Cape Blomidon, situated at the 

 bottom of this gulf J Sir Charles Lyell perceived upon some 

 banks of soft sand-stone^ washed by the waves, two groups of 

 stricB within the distance of a quarter of a mile. The striae 

 were rectilinear, and formed very small angles with each 

 other, which were parallel to the direction of the shore. The 

 peasant who acted as guide to Sir Charles, beitig interrogated 

 as to the origin of these marks ^ answered, " that in the pre- 

 ceding winter, that of 1841, he had seen packs of ice borne 

 away by the tide with a velocity of ten miles an hour, so 

 forming a continuous mass from one side to the other. At 

 the foot of Cape Blomidon they were fifteen feet thick, and 



* See my Memoir, Edin. New Phil. Journ., No. 43, p. 54. 1847. 



t Bulletin de la Soc. Geolog. de France, II. Livre, No. iv., p. 1181. 1847. 



% Travels in North America, vol. ii., p. 173. 1849. 



u2 



