Vol. 52.] FOLIATED GRANITES IN EASTERN SUTHERLAND. 639 



section is taken. The principal constituents occur in allotriomorphic 

 grains. 



The crystalline limestone is associated with a green crystalline 

 granular rock, composed mainly of allotriomorphic grains of pale 

 green pyroxene (omphacite), with altered scapolite, sphene, and 

 pyrite. Along the strike of these rocks, on the sea-cliff at the 

 mouth of the stream, flaggy hornblende-schist with omphacite is 

 exposed ; and in the walls of the gorge flaggy biotite-gneiss occurs 

 with felspar (including oligoclase), quartz, and biotite. Apatite, 

 zircon, and garnet appear as accessories. The foregoing series is 

 pierced by veins of pink microgranite and pegmatite. 



While in the foregoing pages we have adduced evidence suggesting 

 a close relation between the granitoid folia of the complex gneisses 

 and the foliated granites, it ought to be frankly admitted that there 

 is a striking resemblance between the mineralogical constituents of 

 the granulitic biotite-gneiss and the granitic gneiss. 



III. PORTSKERRY TO ARMADALE. 



The crystalline schists into which, in this region, the granitoid 

 rocks have been introduced are of three types : — 



1. Granulitic, seen on the coast from Portskerry to Baligal. 



2. Wavy biotite-gneiss. On the coast this is concealed by the 



Old Red Sandstone of Baligal ; but it is well exposed on the 

 hills about Beinn Ruadh and Bowside. 



3. Granular gneiss of Strathy Point. 



The granulitic type is an ordinary fine-grained flaggy schist, 

 composed of quartz, felspar, and biotite, arranged in a mosaic. 

 No traces of clastic structure can be seen, but the rock is very 

 quartzose. 



The second type is a highly crystalline gneiss composed of felspar 

 (chiefly oligoclase), quartz, and large wavy flakes of very black 

 mica. It will be described in more detail in the section devoted to 

 the Kinbrace area. 



The ' granular ' gneiss is an even, medium-grained rock, also 

 composed of striated felspar, quartz, and biotite ; but of an excep- 

 tional crystalline type, allied to the granulitic, the constituents, 

 however, being on a scale too large for it to be described by that 

 name. Seams of both the other types occur in it, and also peculiar 

 quartzose schists rich in idiomorphic magnetite. 



The granitoid rocks are composed of quartz, felspar, and biotite. 

 The felspar is chiefly oligoclase, but those in the eastern part of the 

 area (Portskerry) contain also porphyritic orthoclase. 



Basic rocks (amphibolites and hornblende-schists) also occur. 

 Their relations are not perfectly clear, but need not be dealt with 

 in this paper. 



In all the schists the granites occur as anastomosing lenticular 

 sills. They are exceedingly numerous, even those large enough to 



