156 ASSOCIATIONS OF [Ch. VIII. 



the cliff to the quartz-vein M, a distance of 1 00 feet, with the 

 exception of about 20 feet, where it is covered by boulders, 

 as in the plan. In this course, it traverses some quartz- veins, 

 and is in its turn traversed by others without any alteration ; 

 but it is heaved by the quartz-vein M about 6 inches, which 

 is the width of the vein at this point. The average size of 

 this vein is about 8 inches; being in some parts 10, and 

 even 12, inches wide. This vein, like D, is at some points 

 indistinct, scarcely to be distinguished from the containing 

 rock ; and, here and there, portions of the latter are imbedded 

 in the veins. Of the quartz-veins, the largest and most inte- 

 resting is F, which may be traced for more than 300 feet. In 

 several places, it is more than a foot wide, containing many 

 elongated drusy cavities, lined with quartz-crystals ; its course 

 is very much curved, but the general bearing of the whole 

 vein, like that of the others in this place, is a little to the 

 eastward of north. Just before it leaves the granite, it is 

 composed of small and irregular strings of quartz ; and after 

 passing this rock, these become mere threads, which, at 

 several points, are not even marked by a continuous crack in 

 the slate, but totally disappear : a little farther on, however, 

 a larger string appears ; and then a large and distinctly 

 formed vein, which continues till lost under the boulders of 

 granite ; first of all heaving the granite vein c 2 J feet, as 

 already stated. When describing this vein, Oeynhausen and 

 Dechen state that the junction is heaved in the same way; 

 but if so, the amount of this movement is equal to 14 feet; 

 and if this irregularity of the granite be a heave, then are 

 also the others on the line of junction, in some of which no 

 vein is present : and it is an important fact, as just men- 

 tioned, that on the line of this quartz-vein near the granite, 

 there is no breach of any description in the substance of the 

 slate. The quartz-vein G runs in the same direction as 

 the last, a little E. of N., forming the line of separation be- 

 tween the granite and the slate, for more than 20 feet: if, 

 therefore, the appearance at the junction where F enters the 



