662 MR DAVID MILNE HOME ON THE BOULDER-CLAY OF EUROPE. 



can be competently relied on to ascertain the quarter from which that agent has 

 come. 



What, then, is the evidence on this point afforded by these phenomena? Let 

 me enumerate the localities where the direction has been clearly ascertained. 



Caithness. — Mr Jameson, in his instructive paper on this subject, enumerates 

 about twenty localities in this county, where " the glacial markings on the rocks 

 showed a pretty uniform direction over the whole district from the N.W." 



Mr Jameson also examined the directions in which " the dark grey mud"— 

 by which he designates the boulder-clay — derived, as he considered, " from the 

 Caithness flags, had moved," and he found that it also had moved from the N.W. 

 He found that the Caithness flags — situated in the N.W. of the county — were 

 themselves covered by " drift of a reddish-brown colour," derived probably from 

 the north-westward.* 



Ross-shire and Argyleshire. — Dr Chambers mentions that " near Rhiconish we 

 find striae coming from the coast — i.e., from the N.W., and passing across a 

 high moor, with no regard whatever to the inequalities of the ground. A little 

 further north, at Loch Laxford, a fine surface is marked with striation from the 

 N.W., being across the valley in which it occurs. At an opening in the bold 

 gneissic coast, which looks out upon the Pentland Firth, there are strong markings 

 in a direction from N.N.W."f 



In the small Isle of Kerrara, opposite to Oban, and also in the Island of Mull, 

 Dr Chambers found striation, pointing in the one case N. 68° W., and in the other 

 N. 60° W.t 



Perthshire. — The lofty mountain of Schehallion has been examined by both 

 Dr Chambers and Mr Jameson. Dr Chambers § found striae on it at a height of 

 above 3000 feet, pointing W. 30° N. ; and Mr Jameson satisfied himself that the 

 striae he saw on the same mountain must have been made " not by ice flowing 

 down the sides of the hill, but by ice pressing over it from the north."|| He 

 adds — " On the Perthshire hills, between Blair- Atholl and Dunkeld, I found ice- 

 worn surfaces of rock at elevations of 2200 feet, as if caused by ice passing over 

 them from the N.W., and transplanted boulders at even greater heights." 



Forfarshire. — Sir Charles Lyell, in the year 1842, pointed out how the till 

 and its embedded boulders had been transported from the N.W. 



Dr Howden, of Montrose, has lately published a paper in the " Transactions 

 of the Edinburgh Geological Society," in which he observes " that the general lie 

 of the range of hills is W.S. W. to E.N.E., while the -direction of the glacial groov- 



* Lond. Geolog. Journ. for 1866, p. 268. 



f Edin. New Phil. Journ. for 1852, vol. liv. 



+ Ibid. 



§ Proceed. Geolog. Soc. of London for January 1865. 



II Ibid. 



