in the neighbouehood op sfdbury, canada. 45 



Discussion. 



The President remarked that the relations of foliation to strati- 

 fication and cleavage would receive much illustration in the study 

 of incipient crystallization in rocks. It was only possible to 

 understand the origin of great changes by finding out what took 

 place in cases of smaller change. 



Dr. Geikie coincided with the President's views of the importance 

 of beginning the study of metamorphosis by investigating the process 

 of smaller changes. He hoped before long to lay a contribution to 

 this subject from the north-west of Scotland before the Society. 

 The Obermittweida conglomerate reminded him of some crushed 

 Cambrian conglomerates in Scotland, where there is a passage 

 from crushed conglomerates and sandstones into mica-schist. 



Mr. RuTLET said that one of the Morlaix rocks represented in the 

 diagram resembled, in microscopic character, some of the slate from 

 Boscastle in Cornwall. He was much interested in the evidence of 

 transition between the two rocks figured in the diagrams. He 

 thought the enlargement of crystals might in some cases give rise 

 to pressure. He then, with reference to the Sudbury rocks, noticed 

 the occurrence of some similar characters in certain Huronian rocks 

 from Michigan. 



E,ev. E. Hill said he had seen the Morlaix beds, and described 

 the locality. The age of the rocks might be determined with 

 fair certainty. 



Mr. Mare said the mode of occurrence of the Obermittweida con- 

 glomerate was in boat-shaped patches that looked like the loops of 

 overfolded synclinals. The fossiliferous rocks of Saxony are un- 

 fortunately found at a distance, but at Hof, in Bavaria, and in the 

 Bohemian basin primordial beds are found. Dr. Beusch considered 

 the Obermittweida rocks very like Silurians near Bergen. 



Mr. Batjeeman had also been at Obermittweida and thought that 

 Prof. Hughes's view was a fairly probable one of the structure of an 

 obscure section. 



Prof. Hughes, in reply, said he did not insist on the identity in 

 age of the conglomerates, of which he exhibited specimens ; all were 

 basement-beds and similar in partaking of the mineral character 

 of the rocks on which they rested. 



Prof. Bonnet said he had scarcely anything to say in reply, ex- 

 cept to thank the speakers for the way they had received his papers. 

 He had unfortunately not been able to examine the rock noticed by 

 Prof. Reusch in Norway. He was trying to work out the whole 

 question of change of structure, approaching it from different sides. 

 He had seen it noticed by Dr. Barrois that some Cambrians occurred 

 near Morlaix. He mentioned instances of patches of sedimentary 

 rocks infolded in old strata, as at Obermittweida, and said that he 

 also was surprised at not finding the matrix of the Obermittweida 

 rock more affected by pressure. 



