308 MESSRS. A. HARKER AND J. E. MARR ON 



The optical characters of the grains seem to indicate orthoclase and 

 albite. lu a few places this groundmass encloses line needles of a 

 mineral with very high refraction and double refraction, straight 

 extinction, and occasionally a faint brown colour ; this seems to be 

 rutile [905]. It will be noticed that in the andesitic rocks, with 

 their higher content of lime, sphene was formed instead of rutile. 

 • These ashes have had a few felspar crystals, up to about jL. inch 

 in length, scattered through the rock. The crystals are now for the 

 most part replaced by new felspar substance, which does not preserve 

 the original orientation ; but enough of the old cloudy felspar remains 

 to prove its nature and to show its twin-structure [904]. 



Rocks of similar appearance to the above are seen on the west 

 side of the high road, where they strike parallel to the neighbouring 

 granite-boundary, with a dip to the east. A specimen was examined 

 from the little " sike " marked on the map [903]. Here the meta- 

 morphism seems more complete. Cyanite, colourless mica, and the 

 green cbloritoid substance are absent or rare, and the conversion of 

 the last-named into dark mica is seen in various stages. Some of 

 the mica is green, but most of it is brown with intense pleochroism. 

 There are a few comparatively large flakes, and these enclose little 

 prisms of apatite. The recrystallization of the groundmass is 

 complete, but there is the same difhculty in determining to what 

 extent quartz may enter into it as well as felspar. There is un- 

 doubted quartz in little veins following the general lamination of 

 the rock as indicated by the mica-flakes. Iron ores are again rather 

 abundant, and are of more than one kind. 



The red highly-metamorphosed rock in contact with the granite 

 in the little ravine behind Wasdale Head Farm is identical with 

 those just described from the eastern margin of the intrusion. 

 Magnetite and brown mica are tolerably abundant ; cyanite is 

 sparingly distributed ; apatite occurs both in the larger mica-flakes 

 and in the general groundmass, which consists as before of an ag- 

 gregate of clear felspar in minute crystals [764]. 



The southern slope of Wasdale Pike is occupied by a succession of 

 highly altered ashes, which, as already stated, we class with the 

 Rhyolitic Group. They are faulted on the north side against the 

 andesitic rocks, on the south against the Coniston Limestone group. 

 They show plenty of dark mica, have a very distinct lamination, 

 and give in the field a suggestion of crystalline schists or even 

 gneisses. At some horizons the presence of fragments of the 

 usual pink rhyolite gives the rocks the character of breccias. 

 There is often some admixture of detrital material, chiefly indicated 

 in the slides by angular clastic grains of quartz [1167]. The 

 general features show only minor variations from the types just 

 described. Eecrystallized felspars, probably accompanied by quartz, 

 make up the bulk of the rock ; magnetite and brown mica are 

 universally present ; colourless mica, cyanite, and apatite occur 

 more sparingly and occasionally. The original felspar crystals are 

 always completely replaced by a mosaic of new felspar, and the 

 little areas are often bordered by magnetite with some brown mica 



