﻿396 ME. Ti 0. B0SW0ETH ON METAMOEPHISM [Aug. I9IO, 



of gneiss, according to Mr. Barrow, is due to the thermal effects of 

 intrusive gneisses among them or below. 



In the 4 Central Highland rocks ' of Banffshire x kyanite is 

 recorded from Glen Rinnes, from near Grantown-on-Spey and 

 various other localities, in pelitic gneiss. Some of these are asso- 

 ciated with epidiorite. In this connexion may be mentioned the 

 kyanitic pseudomorphs after andalusite in the hornfels around the 

 ' Inchbae augen-gneiss ' (Ross-shire). Dr. Flett is of opinion that 

 the andalusite first produced has been subsequently converted into 

 kyanite by pressure. The kyanite is often accompanied by stauro- 

 lite, and sometimes 2 by tourmaline, as in Mull (see p. 391). 



Another common mode of occurrence of kyanite is in associa- 

 tion with quartz in the old pegmatite knots and veins. Specimens 

 from numerous localities may be seen in the Heddle Collection, and 

 a number of localities are cited in Heddle's 4 Mineralogy of Scotland y 

 (vol. ii, 1901, p. 62). 



Though, in some instances, the presence of kyanite may be more 

 or less indirectly connected with older granites and epidiorite 

 masses, in no case does its occurrence appear to be due to contact- 

 alteration by Newer Granites or other unfoliated igneous intrusions. 



In conclusion, it may be stated that where pelitic gneisses have 

 undergone thermal metamorphism at the margin of the Newer 

 Granites (see p. 385), 3 sillimanite, cordierite, and andalusite have 

 been produced. 4 But kyanite, sometimes associated with tour- 

 maline and staurolite in these rocks, is a product of the regional 

 metamorphism, and it is often connected with the quartzose pegma- 

 tization of the pelitic gneiss, whether these pegmatites be segregations 

 or intrusions from below. 



Finally, I wish to acknowledge how greatly I am indebted to 

 Dr. Home, Mr. Clough, and Dr. Flett for their ever-ready advice 

 and help ; in particular to Mr. Clough for instruction and criticism 

 in the field, and to Dr. Flett especially for notes on the cordierite 

 and for his kindness in confirming many of my petrological 

 observations. 



1 ' Geology of Lr. Strathspey ' (Expl. of Sheet 85) Mem. Geol. Surv. 1902, 

 p. 56. 



3 See p. 395. 



3 J. S. Flett, ' Geology of Lr. Strathspey ' (Expl. of Sheet 85) Mem. Geol. 

 Surv. 1902, p. 52 ; J. J. H. Teall, Sum. of Progress of Geol. Surv. for 1898, 

 p. 85 ; also ' Geology of Oban & Dalmally ' (Expl. of Sheet 45) Mem. Geol. Sury. 

 1908. 



4 These minerals are found also in gneisses which are not near Newer 

 Granite. In the South-Eastern Highlands M r. Barrow has described sillimanite- 

 rocks occurring over a wide area, the boundary of which he has mapped for 

 fully 100 miles. He finds the sillimanite in no way connected with Newer 

 Granite intrusions : see Quart. Journ. Geol. Soc. vol. xlix (1893) p. 343 & 

 pi. xv (map) ; also ibid. vol. lx (1904) p. 415. 



