GLACIERS IN GREAT BRITAIN AND IRELAND. 143 



They are formed of Old Ked Sandstone, and on their flanks 

 at elevations of 700 and 800 feet are strewn blocks of 

 gneiss and mica slate, which have been floated across the 

 intervening space over a distance of fifteen miles. One 

 of these blocks on Pitscanby Hill is thirteen feet long and 

 seven across. This is an example on a much smaller scale 

 of the erratic phenomena of the Alps, where enormous 

 blocks have been transported across the great valley of 

 Switzerland from the Mont Blanc range, and stranded 

 along the flanks of the Jura hills. The Pierre a hot, one 

 of these boulders, is one of the noblest monuments in the 

 world of the transporting power of ice. 



The Highlands of Perthshire have been examined along 

 their southern watershed by Buckland and Agassiz,* 

 who detail numerous examples of glacial traces in the 

 shape of moraines, roclies moutonnees , striae and perched 

 blocks. It is to be regretted that the former observer has 

 scarcely recorded a single observation as to the directions 

 of the striae. M. Agassiz, however, mentions that along 

 the valley of the Forth they range from N.W. to S.E., or 

 in other words, radiate from the great line of the Gram- 

 pians seaward. 



Towards the southern extremity of the Highlands the 

 same law obtains, and along the valleys of Loch Lomond 

 and Loch Long the striations point south. f With regard 

 to the former lake I have been informed by Professor 

 Kamsay, that not only its sides but the rock-surfaces of 

 its beautiful islands are completely covered with grooves 

 and furrows. 



In the western Highlands, Agassiz has observed that 

 the direction of the striae along the valleys of Loch Fine 

 and Loch Long are generally S.E., and at Loch Etive and 

 Loch Leven from east to west, 



* Proceedings of the Oeological Society, vol. iii. pt. ii. 

 t Ibid. p. 32S. 



