26 



J. CLIFTON WAKD ON THE GKANITIC, GRANITOID, AND 



5. All the instances of metamorphism brought forward in this 

 part were produced at "great depths ; and the rocks may have been 

 considerably silicated from below. 



6. Although all these various masses treated of were probably 

 formed in the main by the metamorphism of beds in situ, it is pro- 

 bable that some parts of the resulting magma becamo occasionally 

 intrusive among and absorptive of higher beds. 



Appendix. 

 Notices of papers on these Boclcs by other Authors. 



But little more than a bare mention is made by Otley, in his 

 ' Guide/ of the various rocks treated of in this part. 



Prof. Sedgwick described them in his ' Letters ' (1842). He notes 

 the occurrence of the St.-Jolm's rock in two principal masses, and 

 remarks : — " When the largest mass was protruded, it bore upon its 

 surface an enormous fragment of Skiddaw slate, which was thus 

 elevated far above its natural level, mineralized by heat, and jammed 

 against the base of Wanthwaite crag." (This supposed enormous 

 fragment represents the area occupied by the alternations of slate 

 and volcanic rocks at dough Head, on the south of the eastern 

 quartz-fclsite mass.) 



After describing the distribution of the syenite of Ennerdale and 

 Buttermero, Prof. Sedgwick alludes to the alteration immediately 

 around it, remarking that in some places " the black slates are so 

 changed that they can hardly be distinguished from the porphyries 

 of the middle division " (volcanic series). Again — " In some places 

 the formations are in almost inextricable confusion, the slate rocks 

 in one placo abutting on the syenite, in another supporting it, and 

 in a third resting upon it. A great mass of the Skiddaw Slate has 

 been caught up by the syenite, carried to the top of lied Pike, and 

 wedged against the green porphyries of High Stile." Finally, he 

 adds : — " In no one case, however, has this syenite in mass penetrated 

 the green slates or passed over them." 



The same author notices the " almost endless varieties of struc- 

 ture" exhibited by the syenite of Carrock Fell, its crystals of hy- 

 pcrsthene and great quantities of titaniferous oxide of iron dis- 

 seminated through the mass, remarking : — " when on the spot I 

 considered it only as an instance of one of the porphyries near the 

 base of the middle division (green slate and porphyry) in an unusual 

 state of crystallization." 



Mr. J. G. Marshall, in his paper " On the Geology of the Lake- 

 district " &c.*, includes all the syenites with the granites as ineta- 

 morphic, being, he thinks, "but altered beds of slate rock in situ" 



Prof. Harkness, in 1863, alluded to the Carrock-Fell syenite f. 



Dr. Nicholson, in 1869, contributed a paper J entitled "Notes on 

 certain of the Intrusive Igneous Eocks of the Lake District." He 



* Brit. Assoc. Eep. for 1858, Trans. Sect, p. 84. 



t "On the Skiddaw Slate Series," Quart. Journ. Geol. Soc. vol. xix. p. 113. 



% Quart, Journ. Geol. Soc. vol. xxv. p. 435. 



