'Vol. 50.] ANNIVERSARY ADDRESS OF THE PRESIDENT. 1 19 



This may be so, yet the large amount of alkali which analysis 

 reveals in such rocks as the phyllite and staurolite-schist would 

 seem to indicate that, even if fragmental, the materials had not 

 been leached to any extent. There is certainly something curious 

 in the composition of these two rocks. The intensity of the meta- 

 morphism he considers to have been due to the great depth to which 

 the rocks had been lowered when affected by the intrusion, and he 

 thus explains the occurrence of sillimanite and coarsely crystalline 

 gneisses, concluding that the special features noticed may have 

 resulted from action at great depths rather than from any physical 

 conditions due to early geological time. If there is a certain 

 amount of speculation in Mr. Barrow's paper, it may, perhaps, be 

 justified by the uncertainty which yet overhangs the Dalradian 

 schists and all that they contain. 



The Lake District. — An important communication by Messrs. 

 Harker and Marr on the Shap Granite and the associated igneous 

 and metamorphic rocks again raises the question of contact- or 

 thermo-metamorphism in another part of the country and under 

 conditions which, though more limited in extent than the district 

 about Glen Clova described by Mr. Barrow, are, perhaps, on the 

 whole, less difficult of interpretation. Thus, for, instance, the date 

 of the intrusion of the Shap granite can be fixed as having taken 

 place after the deposition of the Lower Ludlow rocks and before 

 that of the basal Carboniferous Conglomerate. The aureole of rocks 

 affected has a width of about three-quarters of a mile measured 

 from the granite-mass, and this width is pretty nearly the same for 

 all the rocks invaded. But although there is, within this range, a 

 progressive metamorphism, nothing like distinct rings or zones can 

 be made out in the Shap Fell district. 



Before considering the main subject of this elaborate paper, viz. 

 the contact-metamorphism of the surrounding rocks, it will be con- 

 venient to notice what the Authors say about the granite itself, and 

 also about certain dykes and sills in their relations to it. The Shap 

 granite is less acid than the Skiddaw and Eskdale granites, whilst 

 the soda and potash are almost exactly equal in the bulk analysis. 

 On the other hand, the orthoclase of the first consolidation, which 

 gives to the rock its well-known porphyritic appearance, contains 5 

 times as much potash as soda. It follows from this that the ground- 

 mass of the Shap granite is considerably richer in soda than in 

 potash. Mineralogical and petrographic details are given, and 



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