Vol. 52.] FOLIATED GRANITES IN EASTERN SUTHERLAND. 633 



37. On Foliated Granites and their Kelations to the Crystalline 

 Schists in Eastern Sutherland. By J. Horne, Esq., F.R.S.E., 

 F.G.S., of H.M. Geological Survey of Scotland, and E. Greenly, 

 Esq., F.G.S., formerly of H.M. Geological Survey. (Communi- 

 cated by permission of the Director-General of H.M. Geological 

 Survey. Read June 10th, 1896.) 



Contents. 



Page 

 I. Introduction 633 



II. Kirktotny to Armadale 636 



III. Portskerry to Armadale , 639 



IV. Kinbrace and Kildonan Area 642 



V. Summary and Conclusions 645 



I. Introduction. 



The detailed mapping of the eastern portion of the County of 

 Sutherland by the Geological Survey has shown that the crystalline 

 schists of that region are extensively penetrated by granites, more or 

 less foliated, which are apparently linked to some extent with the 

 present crystalline characters of these schists. Some of the features 

 presented by these foliated granites have already been described 

 by previous observers. 



In 1862 Prof. Harkness remarked that the mode of occurrence of 

 the granites in the east of Sutherland rather tends to the conclusion 

 that the sedimentary rocks were elevated, flexured, and contorted 

 previous to the period when the granites made their appearance in 

 the sedimentary rocks, and that these granites have conformed in 

 their course to the strike of the previously elevated strata. He 

 further observes that here are abundant features which would 

 support the conclusion that granite is in this district rather the 

 result of an excessive amount of metamorphic action than aplutonic 

 rock as regards its origin. 1 



In 1869 the Rev. Dr. Joass stated that he was inclined to regard 

 the granites in the Kildonan region as partly intrusive and partly 

 metamorphic. He further noted thnt in the most richly auriferous 

 localities certain granitoid rocks, chiefly felspathic, are so intimately 

 connected by interlamination with the flaggy quartzose strata that 

 they almost appear to be the result of metamorphic action upon 

 true sedimentary rocks of the quartzose series, or contemporaneous 

 effusions of plutonic rock. This granitiform rock appears at least 

 in one instance to run across the strike of the decomposed gncissose 

 strata. 2 



1 ' On the Metamorphic Kocks of the Banffshire Coast, the Scarabins, and 

 a Portion of East Sutherland,' Quart. Journ. Geol. Soc. vol. xviii. p. 331. 



- ' Notes on the Sutherland GoldGeld,' Quart. Journ. Geol. Soc. vol. xxv. 

 p. 317. 



