368 ON THE APPARENT DISLOCATIONS [Ch. XV 



for instance, when one vein crosses several others, which are 

 of the same denomination. At Mousehole, two granite veins, 

 of no inconsiderable length and regularity, are heaved by a 

 quartz-vein ; one to the distance of three feet, but the 

 other not more than six inches ; and this happens within 

 a few feet of each other : how could one part of the rock 

 be moved farther than the other? or, how could any 

 displacement happen ? for not many yards off [the quartz 

 vein terminates, and the joints of the slate continue 

 without any derangement across the direction of the vein. 

 The intersections of small contemporaneous veins, however 

 minute, frequently afford similar examples ; and in the case 

 of large veins, such as are explored in mining operations, this 

 condition of the various disconnected parts is so common, that 

 we need only refer to the instances already quoted in the 

 ninth chapter. Nor must we omit to remark that if the lines 

 dividing the layers or laminae of rocks be closely inspected, 

 they will sometimes, especially when the rocks consist of al- 

 ternating layers of different composition or colour, seem to 

 be heaved either with or without the intervention of veins of 

 any description : the opposite layers, however, have not always 

 the same dimensions ; or, as in the instance of gneiss traversed 

 by a quartz-vein, in Fudia, described by Macculloch, the 

 laminae are heaved by the latter as far as it extends, but im- 

 mediately beyond they are not disconnected. * Lastly, veins 

 exhibit the same apparent phenomena of motion without the 

 presence of cross veins or fissures, as in Balnoon mine : and 

 the laminae of rocks likewise afford analogous appearances, 

 as in the gneiss of the Island of Lewis, also described by the 

 geologist just quoted, f Granite-veins, whether of different 

 composition or not, and even the crystalline ingredients of 

 many rocks, also interfere with each other in every possible 

 manner, so as to give representations of all the phenomena of 

 metalliferous veins. 



* Western Islands of Scotland, Plate xi. fig. 3. 

 t Idem, Plate xvi. fig. 5. 



