ASSOCIATED METAMORFHIC ROCKS OF THE LAKE-DISTRICT. 17 



and passing into hypersthenite — and more compact and reddish in 

 the north, passing into the felsite of Eae Crags and Carrock Fell. 



At Round Knott this rock contains most distinct lines of bedding, 

 so that several dips could be taken, the general inclination corre- 

 sponding to that prevailing among alternations of volcanic rocks and 

 Skiddaw Slate in Dry Gill to the north-west. 



4 c. Hypersthenite of Mosedale Crags and Lang Bale. — Lithologi- 

 cally, this rock varies a good deal in character. When most fully 

 developed it is a very coarsely crystalline mixture of hypersthene 

 and darkish felspar, the hypersthene crystals being sometimes an 

 inch or more in length. The felspar, in such a case, -weathers most 

 easily, and the hypersthene stands out prominently, producing a 

 very rough-looking exterior. Occasionally, as at White Crags, the 

 felspar is of a pale or white colour, and the hypersthene occurs gene- 

 rally in smaller crystals than in the rock just described ; so that the 

 aspect varies from a white or grey coarse-grained crystalline rock to 

 a dark and more finely grained one. 



At several parts along the strike of this rock, and especially a 

 little south of Carrock-Pell summit, the coarsely crystalline hyper- 

 sthenite presents a most marked appearance of bedding. Alternating 

 with very coarsely crystalline layers are others of very fine grain, 

 the aspect of the rock from a little distance quite resembling the 

 bedding among the volcanic series. Moreover the dip of this bed- 

 ding is tolerably constant along a line of strike answering to the 

 strike of the volcanic beds on the north, the dip being in this case 

 northwards at angles of from 50° to 70°. Again, at the crags just 

 north of Mosedale, there are most undoubted cases of beds of con- 

 temporaneous trap alternating for short distances with hypersthe- 

 nite and passing into it along the east-and-west line of strike. 



It is somewhat doubtful whether or not the southern boundary 

 of this rock with the Skiddaw Slate is a natural or a faulted one ; 

 most probably it is a faulted boundary, being very straight, for the 

 most part very definite, and corresponding with a probable fault 

 further to the east, on the other side of the valley. The slate, 

 however, is much altered along the line of junction. 



All three of these rocks become somewhat changed in character 

 on approaching Brandy Gill, in and parallel with which there run 

 several strong mineral veins. At the head of the Gill is a small 

 area of bastard or half-developed granite. Below this it would 

 seem that the dioritic and hypersthenic bands approach or cross the 

 Gill, becoming at the same time markedly micaceous. At the foot 

 of the Gill is mica-schist (altered Skiddaw Slate) bordering a very 

 quartzo-micaceous granite. 



II. Microscopical Examination. 



The microscopic structure of the St.-John's quartz felsite and of 

 the Ennerdale syenitic granite has been figured in the Survey 

 Memoir on the Keswick district, pi. i. figs. 5 & 6. In the Plate 

 accompanying the present paper I have given their structure as 



Q. J. G. S. No. 125. c 



