IN GLEN TILT. 367 



mica only. We saw here no liornblende. The granite is 

 small grained, and its felspar reddish, of the same colour with 

 that of the gneiss. The veins in some places run parallel to 

 the planes of the strata, and in others cross them. Some- 

 times there is a gradation between the vein and the gneiss, 

 but the line of junction is often quite distinct. Detached 

 pieces of gneiss, much bent, are imbedded in the granite 

 rock. 



149. The junction is exhibited with remarkable distinctness 

 in a rock, which lies on the brink of the stream, and has re- 

 ceived a polish from it. The surface here exposed measures a 

 few feet each way, and is nearly in the same plane, sloping ra- 

 ther obliquely to the water, at an angle of about 20°. (See 

 Plate XIX, Fig. v.) The part next the water is granite ; that 

 next the shore is gneiss, of which the strata stretch N. 83° E., 

 dipping northerly at an angle of 42'. It will be observed, that 

 the dip of these strata is in an opposite direction to that of all 

 the strata through the lower part of the Glen. The line of 

 junction runs for about four feet, nearly straight, in a northerly 

 direction, and thus crosses the lines of stratification. It is 

 marked with the greatest precision. About the middle, the line 

 is interrupted by a small vein of granite, which projects from the 

 principal mass, intersecting the gneiss parallel to the lines of 

 stratification, and tapering away, till it is lost in the course of 

 a few inches. Near the line of junction, is a small fragment of 

 gneiss imbedded in the granite. — In the loose blocks alono- the 

 declivity of Cairn Vardenoch, we met with many junctions of 

 granite and gneiss, exhibiting facts analogous to those now 

 described. 



150. Eighty yards below the fall of the Merk at the head of 

 the Glen, we found gneiss, dipping about north-east, or per- 

 haps still more to the north, at an angle of between 40" and 

 45'. Near this there are large masses of granite rock, and 



^■^2 also 



