GEOLOGY OF THE OUTER HEBRIDES. 559 



The Lewisian gneiss is known to geologists as the 

 ' Laurentian " gneiss or as the " Fundamental " gneiss, on 

 account of its peculiar character, or its having been related 

 to the gneiss of Labrador and that of the Coasts of the 

 Mouth of the St. Lawrence. The reappearance of this 

 gneiss on the Eastern shore of the North Atlantic basin 

 suggests the belief in a submerged continent " the lost 

 Atlantis " that once extended across this basin. The 

 " Telegraph Plateau " extending across to Newfoundland 

 probably is a higher ridge of this sunk continent. 



THE CONGLOMERATE FORMATION. 



On the east of Lewis, skirting part of Broad Bay and 

 Loch Stornoway, is a peculiar red or chocolate coloured 

 conglomerate which Sir Roderick Murchison, on a cursory 

 view, referred to the Torridon Sandstone formation on the 

 other side of the Minch. A closer examination of this 

 rock shows that it is wholly of local origin and of an un- 

 certain age. Huge boulders of the adjacent gneiss are to 

 be seen embedded in this conglomerate. Indeed, the 

 minerals peculiar to the Lewisian gneiss form the " rubble " 

 or matrix in which these gneiss blocks are found. 



The writer made a detailed examination of this singular 

 conglomerate which he communicated to the Edinburgh 

 Geological Society several years ago, of which paper the 

 following extract may be interesting to Lewismen. 



THE CONGLOMERATES OF LEWIS. 



On the east of Lewis, and wholly within the parish of 

 Stornoway, is an extensive area of Conglomerate, formerly 

 believed to have been Old Red Sandstone. Macculloch, 

 in his Geology of the Western Islands of Scotland, thus 

 refers to it : " It would be concluded, from its general 

 character, to be analogous to the Old Red Sandstone; and 

 therefore, like the rock to which I have compared it, to be 

 the first of the secondary strata. Yet this opinion is 

 subject to serious doubts." Notwithstanding this caveat of 



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