Vol. 65.] IN THE NEIGHBOURHOOD OP ESKDALE. 71 



III. The small Intrusions near Peers Gill. (Fig. 5, p. 72.) 

 Peers Gill is a steep-sided gorge excavated in the Borrowdale 

 Series, partly along a line of fault and partly along an ironstone- 

 vein. It lies in the angle between Lingmell and Great End, and 

 drains the northern slope of Scafell Pikes. 



In the neighbourhood of the gorge numerous exposures of in- 

 trusive rocks are seen, varying somewhat in texture, but resembling 

 each other in chemical composition, and connected by a number of 

 dykes. Somewhat similar rocks also occur on Lingmell Crag, and 

 at Bursting Knotts on the opposite side of Upper Wasdale. 



Specimen 232. — The rock from Bursting Knotts, a small 

 exposure immediately south of the path leading from Wasdale 

 Head to Sty-Head Pass, is dark grey in colour and holocrystalline 

 in texture, the felspars showing signs of a change to epidote. In 

 section, the texture is seen to be granitic, and the rock contains 

 quartz, orthoclase, andesine, a large quantity of brown biotite 

 (now somewhat chloritized), and a considerable quantity of epidote. 



Of the rocks from the foot of Peers Gill, that from 233a is 

 a pink felsitic rock, with a microcrystalline ground-mass consisting 

 for the most part of felspar, but with some quartz. It contains 

 many phenocrysts of andesine and an occasional phenocryst of 

 orthoclase, there being also some epidote and a little haematite. 



Specimen 233 b is a somewhat similar rock, but more basic in 

 composition. It contains numerous pseudomorphs in chlorite and 

 epidote, apparently after a pyroxene. 



Specimen 233c. — This seems to be a highly-altered diorite, 

 and consists very largely of chlorite and secondary biotite, with 

 considerable quantities of felspar playing the part of ground-mass. 



Specimen 234. — Prom the junction of Peers Gill and Girta 

 Gill comes a greyish hemicrystalline rock with a mottled appearance. 

 The ground-mass is very fine-grained, and consists of small clear 

 felspars and quartz. There are numerous phenocrysts of an 

 oligoclase-andesine, which frequently show zonal structure. Deep 

 brown and strongly pleochroic biotite is also abundant. The 

 biotite is fresh, except on the edges of the crystals, where a change 

 to chlorite has set in. There are also numerous pseudomorphs 

 apparently following pyroxene, and consisting of a mixture of 

 calcite, magnetite, and biotite. The rock is an altered andesite. 



The rock from Lingmell Crag is similar, both in texture and 

 in composition, to Specimen 232. 



These rocks show a community of character among themselves, 

 but are petrologically quite unlike anything in the areas occupied 

 by the Eskdale Granite, either in the main exposure or in that at 

 Wasdale Head. It is assumed in the Horizontal Section (Sheet 114) 

 of the Geological Survey, that one of these, namely that on Lingmell 



