in the neighbourhood of ' Loch Nes*. 217 



or that nearest the sea, is the celebrated vitrified fortification 

 of Craig-Phadric. 



On the south side of Loch Ness, is the coarse conglomerate 

 chain of hills named Balcharnoch. From the softer and more 

 iron-shot texture of these conglomerate rocks, and from their 

 gradually passing into sandstone, I am inclined to regard them 

 as not belonging to the quartz-rock. 



To complete my account of the sandstone, 1 have only to 

 add, that its predominating varieties are the common old red 

 sandstone, and a grey micaceous sandstone, very soft and 

 fissile. It is also associated with a bituminous rock, hitherto 

 but little noticed by geologists. This rock deserves a separate 

 consideration. 



7. The exact line of junction between the quartz-rock of a 

 compact texture, and the sandstone, cannot always be accu- 

 rately determined ; but a change is indicated on the quartz- 

 rock, by its very inferior degree of hardness, and by a cor- 

 responding alteration in its texture ; the component particles 

 losing somewhat of their crystalline aspect, and acquiring more 

 of an arenaceous structure. 



At a little distance from the point of junction, the rock as- 

 sumes a more determinate form ; that is, it gradually acquires 

 a stratified arrangement, and the strata are varied in their line 

 of bearing, while they are generally inclined at a very low 

 angle. The circumstance, therefore, of stratification, is a very 

 characteristic difference between the sandstone and quartz- 

 rock. But, besides this distinguishing mark, the sandstone 

 strata appear to be superimposed on the quartz-rock, while 

 the latter, in its relations to granite and gneiss, observes no 

 such determinate mode of position. 



Such are the relations of the quartz-rock. Its connection, 

 on the one hand, with granite and with gneiss, and, on the 

 other hand, with sandstone, have been severally explained. 

 The quartz-rock, therefore, maintains a very important place 

 in geological systems, as, from the nature of its ingredients, 

 from its structure and transitions, it is the probable commence- 

 ment of the great series of sandstone rocks. 



The peculiar quartz-rock now described as so abundant in 

 the vicinity of Loch Ness, has been elsewhere observed ; and 



