'Vol. 62.] BUTTERMERE AND ENNERDALE GRANOPHYRE. 265 



orbicular rock described by Walker. 1 However, it is not clear what 

 is the relation of this dyke to those previously described, since there 

 is a great accumulation of fallen blocks at the critical point. They 

 are certainly not directly continuous, but probably they are closely 

 connected. 



I have very grave doubts whether the dyke shown in the published 

 map at "Wax Knott is really a continuation of the acid dyke of 

 Burtness Combe ; my specimen, taken just below the Scarth-Gap 

 path, is a dark-grej 7 " rock of basic appearance, and distinctly 

 porphyritic. 



(/) Bowness Knott and Herdus. 



At Bowness Knott, on the north side of Ennerdale Water, occurs 

 another comparatively -large area of basic rock. This is a mass, 

 roughly oval in shape, and about a quarter of a mile in its longest 

 diameter. On the south-east side, however, it passes into the 

 granophyre in so irregular a manner that its boundary cannot be 

 exactly laid down on the 6 -inch map. The basic rock is pene- 

 trated by numerous veins of granophyre, which gradually become 

 increasingly abundant, until it shades off insensibly into the main 

 mass. 



The greater part of the basic rock [4769-70] is very similar to 

 that of Burtness Combe. It is essentially of doleritic character, but 

 has a few special peculiarities. The felspars are usually idiomorphic, 

 and seem to have a wide range in composition. Zonary banding 

 is common, and the composition ranges from a rather basic labra- 

 dorite to oligoclase, while a considerable amount of orthoclase appears 

 to be present. Quartz is rare, and there is no sign of micropegmatite. 

 The only ferromagnesian mineral is actinolitic hornblende, repre- 

 senting original augite, and in a few crystals relics of almost 

 unaltered augite can be seen. In places there is a slight tendency 

 to ophitic structure. Ilmenite is abundant, and occurs in rather 

 large crystals. 



Near the junction with the granophyre is a basic rock of peculiar 

 character, in which the ferromagnesian mineral shows a very well- 

 marked needle-like habit. It consists of large felspar-crystals, 

 of columnar habit, ranging from labradorite to oligoclase, together 

 with a good deal of orthoclase, long needles of partly- uralitized 

 twinned augite, chlorite, epidote, ilmenite, and apatite. The rock 

 is much weathered, but it is easy to see that the structure is 

 not uniform throughout ; in some parts of the slice there is the 

 usual association of chlorite and epidote representing biotite, whereas 

 in other parts the chief coloured mineral is uralitized augite. In 

 places there is a good deal of a microcrystalline groundmass, which 

 appears to contain quartz ; but it is not micrographic. Another 

 slice of a similar rock is coarser in texture, and does not show the 

 fine groundmass ; apparently quartz is absent from this type. 



It is evident that this rock is very variable in character in different 



1 Quart. Journ. Geol. Soc. vol. lx (1904) p. 84. 



