D. Milne Home — Glaciation of the Shetlands. 209 



200 miles ; and its '' minimum thickness " is alleged (p. 809) to have 

 been 6000 feet. 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 jDath of 

 least resistance," swung 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 Eastern Seaboard of the Islands 

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

 in a N.W. direction. 



No presumption therefore arises in favour of a N.W. movement 

 of the Ice-sheet in respect of the mathematical reason assigned. 

 But perhaps the observed facts support this N.W. theory ? The very 

 reverse. In the majority of cases where striee were observed and 

 recorded, Messrs. Peach and Home have honestly confessed in their 

 text and their map that the striae do not show a N.W. direction, 

 and they have taxed their ingenuity to explain the discordance, 

 without having to give up Dr. Croll's Ice-sheet. 



For example, in North Mavine, one of the Westerly Islands, they 

 allow, that there are two sets of striae, " one pointing S. 40° W., 

 belonging to the primary glaciation, the other S. 30° E., produced 

 by later glaciers moving down the Bay." But for this supposed 

 primary glaciation — i.e. by Dr. Croll's Ice-sheet — the striae should 

 be W.N.W. ; and if a local glacier is required for the other set of 

 striae, there is no hill or valley pointed out, where one could have 

 been formed. 



On another part of the same island, striee still more discordant 

 occur, and of which the following curious explanation is offered (p. 

 792) : — "Near Fethaland Point two sets of striae wei'e observed, which 

 clearly prove the general movement of the ice during the primary 

 glaciation, and at the same time a separate movement of the loiver 

 portions of the mass, caused by an undertoio. On the headland north 

 of the fishing village, the striae run N.W. and N. 20° W. ; while on 

 the south of the bay, about a mile from the fishing station, the 

 markings on the cliff-heads point N. 6° W.— N. 10° E., N. 20° W. ;— 

 indicating a varying movement in a northerly direction. On ascend- 

 ing the polished slope which overlooks the foregoing examples, the 

 direction is S. 10° — 35° W. This divergence is readily (sic) accounted 

 for, b}'- supposing that the lower current moved in a north and N.W. 

 direction ; while on the slopes of the ridge, the upper current moved 

 towards the S.W., in harmony with the general movement along the 

 Eastern Seaboard of the Mainland." 



A more extraordinary physical phenomenon it is hardly possible 

 to conceive than what is here described, viz. that at the place men- 

 tioned, this great mer de glace split and separated into two currents — 

 one on the top of the other, and then flowed at right angles to one 

 another. No suggestion is made as to the cause which could lead to 

 such a phenomenon. 



DECADB II. — VOL. YIII. NO. V. 14 



