1 64 Geological Society : — 



Part IV. On the Quartz Felsite, Syenitic and associated Meta- 

 morpkie Bocks of the Lake-district. 



This part was treated under the same three heads of Field, Micro- 

 scopical, and Chemical evidence as the last. 



The quartz felsite of St. John's Vale, and the syenitic granite of 

 Buttermcre and Enncrdale, lie for the most part at the junction of 

 the volcanic and Skiddaw series, and seem by their line of strike, 

 and by the occasional presence of bands of slate or volcanic rock, 

 enclosed within or running through them, to represent the transition 

 beds between the two series, metamorphosed in great measure in 

 situ. Both microscopic and chemical evidence demonstrate the pos- 

 sibility of this process. 



Evidence gathered in the field, and microscopic and chemical 

 examination, all seem to suggest that the rocks of Carrock Pell &c. 

 represent the base of the volcanic series, consisting largely of con- 

 temporaneous traps thrown into a synclinal, the axis of which 

 ranges generally east and west, and metamorphosed into rocks of 

 greatly varying character, such as sphaerolitic felsite, hypersthenite, 

 and diorite. 



Although all the 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 became occasionally 

 intrusive among and absorptive of higher beds. 



In an Ajipendix notices of papers on these rocks by other authors 

 were given. 



Part V. General Summary. 



In this part the leading results of the four preceding divisions of 

 this memoir were briefly brought forward, followed by the dis- 

 cussion of various considerations relating to metamorphism, under 

 the following heads : — (1) Granite at various depths ; (2) how far 

 granite may be an ultimate universal product of metamorphism ; 

 (3) distribution of metamorphism (selective metamorphism) ; (4) 

 classes of metamorphism. 



The paper was illustrated by a large geological map of the 

 northern part of the Lake-district, by a geological model of tie 

 Keswick district, by rock-specimens, and large coloured photographs 

 taken from water-colour microscopic drawings made by the author. 



December 15, 1875. — John Evans, Esq., P.E.S., President, 

 in the Chair. 



The following communications were read : — 



1. " Notes on the Physical Geology of East Anglia during the 

 Glacial Period." By "W. H. Penning, Esq., E.G.S. 



The author wished it to be understood that his remarks were 

 intended to form a sketch, rather than a detailed account, of the 

 subject to which they relate. He intended to explain the origin 

 of the so-called " middle glacial" gravels and sands, to account for 

 their occurrence in certain areas and their non-occurrence in others 

 where they might reasonably have been expected, also to briefly 

 describe a certain series of gravels of doubtful age and origin in 

 the Cambridge valley. 



