184 



more than an inch in length, form a conspicuous feature in almost 

 every specimen of the rock. On a smaller scale they occur, again, 

 in sucli dykes as that of Armboth. Felspar crystals, resulting 

 from metamorphic action, occur in several areas contiguous to 

 great masses of plutonic rock, such as the granites. Good 

 examples of this may be seen in the metamorphosed tuffs of Bala 

 age in the neighbourhood of Shap Wells, and at Shap summit 

 cutting. Mr. Ward has mentioned several other localities where 

 phenomena of the same nature may be observed. 



The species of the Felspar Group yet noted as occurring in 

 Cumberland and Westmorland are Orthoclase, Oligoclase, 

 Labradorite, Andesine, Albite, and Microcline. Mr. Bryce 

 M. Wright mentions the occurrence of Glassy Felspar in a 

 Molybdena vein on Carrick. If this is Sanidine, that would add 

 another species to the members of the group already enumerated. 



The remarks made under the last heading apply to some extent 

 also to the members of the Mica group, which stand next. ' There 

 are, however, some facts connected with the mode of occurrence 

 of Mica that call for remark. Mica occurs exclusively as a rock- 

 constituent with us. It is found under three conditions — -(i) cognate 

 with the rock, as in the Mica of granites and other plutonic rocks ; 

 (2) as a product of metamorphism, as in the well-known Mica-schist 

 of the Cawda; and (3) as 'a derivative material, as in ordinary 

 sandstones. The commonest species here are Biotite and 

 Muscovite ; but other species, or sub-species, occur as occasional 

 constituents of rocks. It is a point of some interest to note that 

 native Mica, like native quartz, in all but' exceptional cases, is 

 conspicuous by its absence in nearly all the volcanic rocks of the 

 Lake District. This fact has a bearing of considerable importance 

 upon the question of the correlation of the volcanic "Green Slates" 

 of the Borradale Series with the detrital and sedimentary " Green 

 Slates" of the Craven area,* near Ingleton and Horton in Ribbles- 



* It would be well to distinguish these Ingleton Green Slates by some local 

 name, as their precise geological position has not been clearly made out. I 

 believe they are chiefly of true Bala age, like the lavas at Rake Brow, Melmerby ; 

 the rocks below the 6.VV. face of Roman Fell; the beds at Shap summit 



