D. Milne Home — Glaciation of the Shetlands. 453 



large deflections may exist elsewhere, and without these gentlemen 

 having been aware of them. 



Before concluding these remarks on the subject of rock striations, 

 may I venture to suggest, that there should be a re-examination, with 

 the view of ascertaining whether many, or any of them, give indica- 

 tions of the ends which were first cut in the rook. During the last 

 two years, I have found many examples, notice of which may be 

 seen in the Eeports of the Edinburgh Royal Society Boulder Com- 

 mittee. If the deepest incisions in the Western Islands of the Shet- 

 lands are at the S.E. ends, they will verify the views of Messrs. 

 Peach and Home. If at the N. W. ends, they will justify the doubts 

 and criticisms which I have presumed to offer. 



III. On a review of the whole evidence which Messrs. Peach and. 

 Home have adduced in support of the Scandinavian mer de glace 

 theory, I have only to say, that the more the matter is discussed, the 

 more difficult it appears to me to support it. 



Tlie idea of an immense mass of ice, with an alleged thickness of 

 6000 feet, a length of 400 miles, and 200 miles in width, sliding 

 over the bottom of the North Sea, and whenever it reached, the Shet- 

 lands, swinging out of its natural course, to follow a new path at 

 right angles to its previous course, seems to me utterl}'^ inconsistent 

 alike with precedent and principle ; and the evidence by which 

 this phenomenon is sought to be established, as might have been 

 anticipated, entirely fails. The boulders, instead of showing trans- 

 . port in accordance with the supposed march of this mer de glace, 

 show transport irreconcileable with it. The rock striations founded 

 on are also so discordant, that I must express my surprise at the 

 assertion of Messrs. Peach and Home that " the islands have been 

 grooved and "striated in one determinate direction" (p. 808). On 

 the contrary, it seems to me undeniable that the directions of the 

 stri93, not only on the different islands, but on the same island, and at 

 places not far from one another, are most diverse and contradictory ; 

 some proof of which is afforded by the ingenious but inadmissible 

 conjectures offered to explain them. 



In short, it appears to me that the circumstances brought out by 

 the Memoirs of Messrs. Peach and Home, have made out a very 

 strong case for the theory of floating ice moved by tides and winds, 

 as in that way it is possible to explain how fragments of rock were 

 carried from one island to another, and at the same time striations 

 made on the rocks in different directions. 



There are, however, strong grounds for believing that at the time 

 of the Boulder transport, a current prevailed in the North Atlantic 

 from the N.W., and therefore I am not surprised that the striations 

 of the rocks on the western seaboard of the Shetlands should run in 

 a direction N.W. and S.E., as Messrs. Peach and Home state. 



That also is the direction of the striae in the Hebrides, and on the 

 coasts of Argyllshire facing the Atlantic; — aad in all these cases 

 the striating agent has been shown to have come from the N.W. 



In concluding my review of these Memoirs, I wish in all sincerity 

 to repeat my regret, should Messrs. Peach and Home feel annoyed 



