678 THE CAULDK0N- SUBSIDENCE OF GLEN COE. [Nov. 1909. 



He was inclined to differ to some extent from the Authors as to the 

 amount of metamorphism produced by this intrusion. Mr. Maufe 

 had specially referred to the description of the rocks supposed to 

 be altered by the Cruachan Granite. One of these was mentioned 

 as vividly recalling the altered dark schist of Glen Callater, near 

 Braemar. Now, this rock occurred as an inclusion within the 

 Lochnagar Granite, which was a mass some 10 miles in diameter ; 

 and it was supposed that the alteration of the dark schist must be 

 due to the granite. The speaker had shown that it could be 

 matched at intervals for a distance of 25 miles from the granite : 

 the crystallization was thus clearly due to the older Highland meta- 

 morphism, and the newer intrusion had little or no effect on it. 



Mr. E. B. Bailey thanked the Fellows present for their cordial 

 reception of the paper, and especially for their criticisms. In reply 

 to the President, he pointed out that the frequent association, and 

 even occasional minor admixture, of contemporaneous igneous 

 intrusions with the flinty crush-rocks of Glen Coe was of the nature 

 of an accident. In many cases in this same district it could be 

 shown that films of flinty crush-rock originated without the inter- 

 vention of any igneous action. The independent dynamical origin 

 of flinty crush -rocks had also been demonstrated by Mr. Clough in 

 the Cheviots and in the North-West Highlands, while Sir Thomas 

 Holland had proved the same point in India. In reply to Dr. Teall, 

 he said that the parallel d^vkes of stretched regions were the counter- 

 part of the parallel folds of compressed regions ; while the yielding 

 fluid-filled subterranean cauldrons might be regarded as counter- 

 horsts. Horsts, owing to their rigidity, localized folds; counter- 

 horsts, owing to their weakness, localized cracks, which, filled in 

 contemporaneously with igneous material, gave rise to dykes. In 

 reply to Mr. Barrow, he said that the evidence of extensive contact- 

 alteration, which had been described by Dr. Teall & Mr. Kynaston 

 along the southern and western margins of the Cruachan Granite, 

 was beyond question. 



