370 B. N. Peach ^ J. Home — Glaciation of the Shetlands. 



deflecting the Scandinavian mer de glace to the N.W. on the west 

 side of Shetland.^ 



Mr. Milne Home next proceeds to inquire whether the strise 

 suppoi't this movement towards the N.W. on the western seaboard. 

 Again, we must be excused for calling attention to his misapprehen- 

 sion of the facts. The various examples quoted by him do not bear 

 on this question at all, as they occur on the eastern seaboard of 

 Northmavine on the Mainland. Northmavine is not one of the 

 westerly islands, but the northern parish of the Mainland, and by 

 referring to page 792 of our paper, it will be seen that all the 

 instances qnoted by him (Geol. Mag. p. 209) are clearly described 

 as occurring on the eastern seaboard of Northmavine in the Main- 

 land. - 



4. The various boulders cited by Mr. Milne Home may be 

 satisfactorily explained by the theory advocated in our paper, save 

 the blocks of actinolite schist on Papa Stour, which, according to 

 Hibbert, could only have come from Hillswick Ness. Mr. Mihie 

 Home asks why we omitted to take notice of the boulders recorded 

 by Hibbert. and the answer is simply this : that in the summary of our 

 work which appeared in the Quart. Journ. of the Geol. Soc. we confined 

 ourselves exclusively to our own observations on the glacial phe- 

 nomena. The original MS. contained a detailed reference to Dr. 

 Hibbert's paper " On the Direction of the Diluvial Wave in the Shet- 

 land Isles." ^ In our published paper we merely stated the conclu- 

 sion which he came to, viz. " that the great diluvial wave which 

 swept over the low elevations of the whole of Scotland and England 

 had in the latitude of Shetland a north-easterly origin, or in other 

 words, a south-westerly direction." * It is somewhat remarkable 

 that Hibbert should have arrived at this conclusion 50 years ago, 

 merely from an examination of the boulders lying on the surface. 

 He paid no attention to the ice-markings or the dispersal of the 

 stones in the Boulder-clay. No one could allege that he was pre- 

 possessed in favour of the theory that Shetland was glaciated by 

 Scandinavian ice. And yet, almost all the boulders described in his 

 paper confirm our conclusions as to the direction of the ice-move- 

 ment during the primary glaciation ! 



Following the order in Hibbert's paper, the blocks of actinolite 

 schist on Papa Stour fall to be discussed first. Though we examined 

 every mile of the coast-line, and crossed the island, we did not light 

 on these blocks, but we have not the slightest doubt that they are 

 to be found. Hillswick Ness, from which these blocks were trans- 

 ported according to Hibbert, lies about 12 miles to the north-east 



^ Quart. Journ. Geol. Soc. vol. xxxvi. p. 648. 



2 Mr. Milne Home seems to consider the separate movements of the upper and 

 lower portions of the ice-sheet as indicated by the striae near Fethaland Point, an 

 " extraordinary physical phenomenon." Evidence of a similar double movement 

 has been observed by Professor Eamsay among the Yorkshire hills, and Professor 

 Hull has described another example in connexion with the Lough Erne Valley. 

 See " Physical Geology and Geography of Ireland," by Prof. Hull, p. 239 ; also see 

 " Great Ice Age," 2nd ed. p. 290. 



3 Edin. Journ. Science, vol. iv. p. 88. * Q. J. G. S. vol. xxxv. p. 779. 



