A. Somervait — Banded Rocks of the Lizard District. 507 



My own observations on the nature of the banding I shall now 

 give from a few typical localities, copied from notes as I made them 

 on the spot. 



Kennack. — The banded granulitic rocks here consist of a dark 

 basic, or diorite portion, and an acid or granitic one which greatly 

 predominates, varying much in texture and composition, ranging in 

 colour through pinkish-white or grey, to pale red, dark red, and 

 brown. Sometimes these acid or felspathic bands ai - e themselves 

 banded with paler and darker portions of their own composition, thus 

 forming a distinct inter-banding of their own. Sometimes the lines 

 of demarkation between the diorite and granitic bands are of the 

 most perfect nature, but this is not always so, as they frequently pass 

 over into each other by the finest gradations. Besides the inter- 

 mingling of both of these rocks in the dykes cutting the serpentine 

 of the cliff here, I have noted the fourth dyke west from Kennack as 

 exhibiting a good example of banding in a dyke. The first dyke is 

 also a good instance. 



Caerleon and Little Coves. — In both of these coves banded 

 granulitic rocks occur. The most notable feature is at Little Cove, 

 where there is a type of the granulitic not of a very granitic texture, 

 of a reddish colour, rather slightly and confusedly banded, not by 

 dark diorite bands, but by paler and darker shades of red of similar 

 composition to its base. South of Caerleon Cove there are pale 

 felspathic varieties banded with still paler bands of felspar. Both 

 of these varieties occur elsewhere. 



Kildown Cove. — Here there are great masses of reddish granulitic 

 rock without any banding whatever, which, however, at some 

 distance off becomes dioritic and banded in the usual way. Here 

 is the rudely circular mass of rock already referred to, 1 made up of 

 the concentric layers of diorite and granulitic, with the latter for its 

 centre. 



Flag-staff Quarry, Kildown Point. — The banded structure can here 

 be studied in many of its varieties. The banding in places is of 

 a regular and persistent character, fining down to alternate parallel 

 lines of dioritic and granitic minerals as thin as a sheet of paper, or in 

 broader bands composed of hornblende and felspar mingled together. 

 Highly irregular and lenticular banding also occurs, and in some of 

 the diorite bands are small elliptical masses of the granitic portion, 

 quite isolated from each other. At the top of the quarry where these 

 rocks may be seen (seemingly) cutting through the serpentine, the 

 banded structure is still traceable, but on a smaller scale, and much 

 more confused, the mass of the rock also being modified from its 

 contact with the serpentine. 



The Balk. — Here the banded "granulitic" rocks are in great force, 

 consisting principally of the acid and felspathic type, the dioritic 

 portions being very subordinate in comparison to the other. These 

 quartzo-felspathic and granitic rocks are highly banded, not so much 

 with bands of diorite as with portions of their own composition of 

 various textures and colours, according as they consist of felspar 

 1 Geol. Mag. Vol. VII. p. 166 (1890). 



