Vol. 62.] BUTTEEMEEE AND ENNEEDALE GBANOrHYEE. 273 



EXPLANATION OF PLATES XXVII & XXVIII. 



[All the figures are magnified 21*5 diameters.] 



Plate XXVII. 



Fig. 1. [4750] Granitic margin of the Buttermere laccolite, near Scale Force, 

 showing interstitial quartz. 

 2. [4748] The same, showing idiomorphic plagioclase. 



Plate XXVIII. 



Fig. 1. [4755] Granophyre, Boathow Crag, Ennerdale, half a mile from the 

 margin, showing micropegmatite of a medium degree of fineness. 

 2. [4759] Granophyre, Sail Hills, Ennerdale, If miles from the margin, 

 showing micropegmatite of very fine texture. 



Discussion. 



The Peesident regretted the absence of the Author, owing to 

 illness. He welcomed the very interesting paper, and congratulated 

 himself that he had suggested that the Author should undertake 

 the study of these rocks. The Author had referred to Clifton 

 Ward's work — work which was naturally acknowledged by all who 

 had subsequently worked in the district. In Ward's time the 

 study of differentiation of magmas had not been extensively 

 followed, and the Author had taken advantage of work which had 

 been done in this direction, with very good results. He had been 

 well advised in alluding but briefly to the relationship between the 

 granophyre and the ' tectonics ' of the district. The paper was 

 really the first part of a study of the area, the second part of which 

 would deal with the metamorphism. 



Dr. C. G. CtrLLis said that he had been interested to hear that, 

 from a consideration of the granophyric structures of the mass, the 

 Author had arrived at the conclusion that it must have been 

 formed under conditions intermediate between the plutonic and 

 the hypabyssal ; and it had occurred to him that the accuracy of 

 that conclusion might, to some extent, be tested in an interesting 

 manner. The Buttermere and Ennerdale Granophyre was one of 

 at least three masses of acid igneous rocks which, in that region 

 of the Lake District, had been intruded into or against the Skiddaw 

 Slate. The other two he had in mind were the Threlkeld (St. 

 John's) Microgranite and the Skiddaw Granite. Of these the latter 

 had consolidated under typical plutonic conditions, the, former 

 under hypabyssal. In the case of the plutonic rock, the contact- 

 metamorphic effects produced in the Skiddaw Slate were of the 

 most striking character, the sediments having completely recrystal- 

 lized for some hundreds of feet, at least, from the junction ; but in 

 that of the hypabyssal rock the effects had been very slight, being- 

 limited to the hardening of the slate at the junction, so as to form 

 a selvage not more than a few inches thick. If the Buttermere 

 and Ennerdale Granophyre had indeed been formed under conditions 

 intermediate between the plutonic and the hypabyssal, it might 



