B. N. Peach 8^ J. Some — Glaciation of the Shetlands. 369 



can easily understand how, in a group of scattered islets, the direction 

 msij vary from W.S.W. to S.W. and S.S.W., according to local de- 

 flections. 



Mr. Milne Home questions the possibility of local glaciers giving 

 rise to the south-easterly striae on the east coast of the Mainland 

 between Lerwick and Dunrossness. When we consider the high 

 northern latitude, and the severe Arctic conditions which then 

 prevailed, there is nothing improbable in the supposition that local 

 glaciers existed in that long tongue of land where the hills range 

 from 500 ft. to 800 ft. in height. The moraine heaps and morainic 

 deposits which are so plentifully developed in Shetland as siirely 

 point to the existence of local glaciers as the large mounds in our 

 Highland glens and in the upland valleys of the South of Scotland. 



In his concluding remarks regarding the striee on the eastern sea- 

 board of Shetland, Mr. Milne Home states, " that so far from con- 

 firming the theory of an invasion of an Ice-sheet from the N.E., 

 most of these striee are at right angles to that direction." To this 

 we reply that out of 197 instances of ice-markings recorded by us in 

 Unst, Yell, Fetlar, Whalsay, the Outskerries of Whalsay and the 

 eastern seaboard of the Mainland, 159 point W., W.S.W. to S.S.W., 

 while 38 point in a south-easterly direction. 



Mr. Milne Home takes exception to our statement that the ice- 

 sheet when it reached the crest of the Mainland veered round to the 

 N.W. so as to follow the path of least resistance, and from the tenor 

 of his remarks he has evidently misunderstood our argument. To 

 quote from his paper, " Now this huge mass, it is said, when it 

 impinged on the Shetlands, and reached the crest of the Mainland, 

 * was deflected by the opposing high ground,' and in order to 

 'follow the path of least resistance,' swimg round to the N.W. The 

 Shetlands form a group whose axis is N. by E. and S. by W. If it 

 be possible to imagine, that a body of ice of the above gigantic 

 dimensions, bearing down on these Islands from the N.E., could have 

 its course changed by impinging on them, so as to seek the path 

 of least resistance, its progress would have been along the Eastei'n 

 Seaboard of the Islands in a direction S. by W., and not across the 

 backbone of the Islands in a N.W. direction." 



We endeavoured to show that the ice-sheet was deflected by the 

 opposing high ground before it reached the crest of the Mainland. 

 In fact, the deflection along the eastern seaboard, suggested by Mr. 

 Milne Home in the foregoing passage, is what we believe to have 

 been the case. The ice-sheet as it impinged on the Shetland 

 frontier was deflected towards the S.W. and S.S.W. by the backbone 

 of the group, but eventually the pressure of the advancing mass was 

 sufficient to compel it to override even the highest hills, and on 

 reaching the crest of the Mainland, having surmounted the resisting 

 higVi ground, it naturally veered round to the west. Our recent 

 work in Orkney, however, enables us to account for much of this 

 northing along the western seaboard of Shetland. The Orcadian 

 group was glaciated b}' Scotch ice moving in a north-west direction, 

 and the latter ice-sheet must have had a considerable influence in 



DECADE II. — VOL. VIII. — NO. VIII. 24 



