328 THE SHAP GK.VNITK AND ASSOCIATED ROCKS, 



garnets of one or two localities in Saxony. The paper appeared to 

 be one of exceptional interest and value. 



Mr. Bakrow was much interested in the Authors' list of minerals 

 developed by contact-metaraorphism. The light they had thrown 

 on the origin of cyanite was particularly valuable to geologists 

 working in the Central Highlands, where cyanite schist occurs on 

 a large scale. In one instance a broad belt of this schist follows 

 the outcrop of an igneous gneiss for some miles in such a manner as 

 to suggest contact-metamorphism. The crystals of cyanite show 

 little or no signs of deformation, and if developed by contact-meta 

 morphism seem to point to the conclusion that the igneous rock 

 originally consolidated as a gneiss. 



Mr. Marr, in reply, recapitulated the reasons which had caused 

 the Authors to connect granite, felsites, and mica-traps alike with 

 the existence of a deep-seated magma, without asserting which por- 

 tions of this were first consolidated. The movements in the Pennine 

 Chain to which they had referred were those pre-Carboniferous ones 

 which aifected only the Lower Pala30zoic rocks. Though the map 

 of dykes exhibited was necessarily diagrammatic, the directions of 

 those dykes which they had not themselves examined were taken 

 from tjie published maps of the Geological Survey. 



He believed that the metamorphism produced by the granite 

 might throw some light upon the changes which had occurred in 

 the rocks of a " regionally metamorphosed " area. The Authors had 

 attempted to show that the Sha]^)-granite intrusion was connected 

 with earth-movements. If such movements had taken place to a 

 greater extent, dynamic metamorphism would doubtless have 

 altered the granite, the dykes, and the various sedimentary and vol- 

 canic rocks, but the pre-existing contact-metamorphism might still 

 remain as a factor in the process of regional metamorphism. 



Mr. Harker remarked that although new-formed felspar occurs 

 in the most metamorphosed types of all the rocks studied, the 

 minuteness of its grains and their pellucid appearance render it in 

 many cases difficult to distinguish from quartz. Cyanite as a 

 "contact-mineral'' had been recorded by Losscn in the Harz. 



Mr. Teall and Dr. Hatch also spoke. 



