ASSOCIATED METAMOKPHIC ROCKS OF THE LAKE-DISTRICT. Zl 



notes the regular jointage of the quartz -felsite (called syenite) of 

 St. John's, and its resemblance to bedding in the quarry nearest 

 Threlkeld, and describes the rock in general. The metamorphism 

 of the Skiddaw Slate in the Ennerdale district, around the syenite, 

 is contrasted with the less amount of change occurring along the 

 junction near Buttermcrc. The strike of the Carrock-Hill porphyry 

 is noticed as similar to that of the bedded trap. In conclusion, the 

 author is disposed " to look upon the igneous masses in question as 

 the roots of the ancient vents from which were derived the alter- 

 nating ashes and traps which together compose almost the whole of 

 the green-slate series. Whether they are to be regarded as being 

 produced by an alteration and fusion of the Skiddaw slates in situ 

 is another question, and one which is at present incapable of solu- 

 tion. Phenomena, however, are not wanting which would appear 

 to favour this view." 



Prof. Phillips, in his article in Black's l Guide/ speaks of the 

 " principal mass " of " the syenitic and porphyritic rocks of the 

 Yale of St. John " having " been forced up amongst the brecciated 

 slates." The Ennerdale and Buttermere syenitic masses, he states, 

 are " evidently irruptive," and " have been forced through, and 

 perhaps have spread over the middle slates " (volcanic scries). The 

 same conclusion is also drawn in the case of the " syenites and por- 

 phyries round Carrock Pell and High Pike." 



EXPLANATION OP PLATE II. 



Pig. 1. Altered Skiddaw Slate passing into quartz felsite, Clough Head, St. 

 John's Vale. Magnified 30 times. 



2. Quartz felsite of St. John's Vale. Magnified 30 times. 



3. Altered Skiddaw Slate, summit of Eed Pike. Magnified 70 times. 



4. Altered Skiddaw Slate, near Scale Porce, Buttermere. Magnified 70 



times. The somewhat oval liquid-cavity in the large quartz space is 

 magnified 210 times. 



5. Syenitic granite, Scale Force, Buttermere. Magnified 30 times. 



6. Spherulitic felsite, Carrock-Fell summit. Magnified 10 times, pola- 



rized light. 



7. Hypersthenite, White Crags, Carrock. Magnified 10 times, polarized 



light. 



8. Pine-grained band in coarsely crystalline hypersthenite ; these bands 



dip regularly into the mountain-side, like ordinary bedded deposits. 

 Magnified 10 times, polarized light. 

 The above figures were drawn in water-colours, direct from the microscope, 

 by the author. 



Pakt Y. — General /Summary. 



Contents. 



Leading Eesults of the several parts — Considerations relating to 

 Metamorphism. 



1. Granite at various depths. 



2. How far Granite may be an ultimate universal product of 



Metamorphism. 



3. Distribution of Metamorphism. 



4. Classes of Metamorphism. 



