Vol. 65.] INTRUSIVE BOCKS IN THE NEIGHBOURHOOD OF ESKDALE. 61 



at the time of intrusion of the granite, and that the margin of the 

 latter was rapidly chilled, further intrusion having lifted the over- 

 lying masses and produced the dome-like structure indicated by the 

 dips of the Borrowdale Series and of the granite-surface. 



There is some slight indication of successive intrusion on the 

 flanks of Hollinghead Bank, near Beckfoot Station on the Raven- 

 glass & Eskdale Railway. At the points marked 160, 162, 163, 

 164, & 168 on my MS. maps the granite is coarse-grained and 

 reddish in colour, while lower down the slope (that is, farther from 

 the upper surface of the intrusion) at 88, 89, & 90, where a small 

 quarry has been opened, it is fine-grained and grey in colour. The 

 same fine-grained variety occurs at the quarry near Spout House 

 (91 & 92) ; while above, on Hollinghead Crag, at 172 & 173, 

 coarse granite of the normal type is to be found. The boundary 

 of this low-level fine-grained variety is difficult to trace, owing to 

 the profusion of fallen blocks which encumbers the slope ; but, so 

 far as I was able to determine its position, it appeared to run 

 roughly parallel to the upper surface of the intrusion. 



The small exposure of granite at Wasdale Head is of the same 

 general type as that found in the Mitredale and Eskdale sections, 

 and exhibits many of the same marginal phenomena, although these 

 are not so well marked as in the case of the larger mass. In 

 several places veins of granite may be seen penetrating the Borrow- 

 dale rocks, as, for example, in Gable Beck and near the "Waterfall 

 in Mosedale Beck. 



Petrology of the Normal Granite. 



There are, apart from the marginal varieties, two main types 

 to be seen in the Eskdale Granite — one occupying the north-eastern 

 and by far the larger portion of the main outcrop together with 

 the smaller mass at "Wasdale Head, being coarse-grained and 

 containing a considerable quantity of muscovite and a smaller 

 amount of biotite, usually much decomposed ; and the other and 

 far less widely distributed variety occurring in the neighbourhood 

 of "Wabberthwaite in the south-west, where it is now extensively 

 quarried. It contains a much larger proportion of black biotite, 

 and somewhat resembles in general appearance some of the darker- 

 coloured varieties of the Dumfries-shire granites. 



The rocks vary greatly in colour, being in some localities white 

 to grey, while in others they are pink or even red. 



Quartz is very plentiful in all the varieties, and is usually free 

 from strain-shadows, although these occur in some parts near the 

 great lines of fault and near the margins of the intrusion. Occa- 

 sionally small flakes of muscovite occur embedded in the quartz- 

 crystals, which also contain fluid and gas-inclusions, as described 

 by Clifton "Ward and others. 



The felspars include orthoclase, oligoclase, and a perthitic 

 intergrowth of orthoclase and oligoclase. This perthitic inter- 



