590 J. CLIFTON WARD ON THE GRANITIC, GRANITOID, AND 



Part II. — On the EsJcdile and Shap Granites with their associated 

 Metamorjphic Eoclcs. 



[Plate XXXI.j 



Contests. 

 Introduction. 



I. Litbological Character. 



1. General relations. 



2. First Stage. 



3. Second Stage. 



4. Third Stage. 



5. Boundary-lines of granite. 



II. Microscopical structure. 



1. First Stage. — Felstone-like altered ash. 



2. Second Stage. — Felstone-like with a purplish hue. 



3. Third Stage. — Purplish base with imperfeet crystals porphyritically 

 imbedded. 



4. Fourth Stage. — Bastard granite. 



5. Fifth Stage. — Granite. 



III. Chemical composition. 



1. Rock-analyses. 



2. Eemarks on the analyses. 



3. Order of chemical changes. 



4. On the Phosphoric Acid present in the Volcanic Series. 



Summary. 

 Appendix. 



Introduction. 



In the first part of this memoir the two granitic masses of Esk- 

 dale and Shap have been considered in connexion with the liquid- 

 cavities enclosed in the quartz of each. The evidence afforded by 

 these seemed clearly to indicate a deeply seated origin ; and other 

 considerations were brought forward, all tending to negative the idea 

 of an immediate connexion between the granitic masses and the 

 volcanic rocks around them, in the sense of volcanic continuity. The 

 question now arises, If these granitic masses were formed beneath a 

 great thickness of overlying rocks, can we point to the rocks out of 

 which they may have been so formed? I think that we can, and 

 may affirm with great probability that the granite was produced, in 

 great measure at all events, by the extreme metamorphism of the 

 volcanic rocks, such as we now see surrounding it on all sides. 

 That it was exclusively due to the melting-down by aqueo-igneous 

 fusion of these rocks I would not venture to assert ; in all proba- 

 bility the heated mass below partly ate its way upwards, at the 

 first, to within reach of the volcanic series, the roclcs of which were 

 then metamorphosed to such an extent as to assume the granitic form 

 and structure. The evidence for this, in the lithological character, 

 in the microscopic structure, and in the chemical composition of the 

 metamorphosed volcanic rocks, will form the substance of the fol- 

 lowing pages. 



For views of previous writers on this subject, see appendix, p. 602. 



