1824.] the Rocks of Mount Sorrel, fyc. 17 



which always are in a direction different to that of the cleavage 

 plane of the slates — never at right angles to it. 



It is impossible to view the rocks of Charnwood Forest either 

 in situ, or in hand specimens, without being forcibly struck with 

 their resemblance to several of those in many parts of North 

 Wales. The less perfect slates lying between the granular- 

 looking and imperfectly slaty rocks above Nantfrancon quarry, 

 almost perfectly resemble the coarse slates of the Swithlancl 

 quarries ; while in several of the granular varieties of the rocks 

 of the two tracts, the resemblance is absolutely perfect. Chlo- 

 rite is abundant, and appears to be the colouring matter of both ; 

 and both include small crystals of transparent quartz and of 

 felspar, when the rock is very coarsely slaty. In Charnwood 

 Forest, however, we perceived in many places layers containing 

 angular fragments of quartz, and which are left adhering to the 

 surface, owing to the decomposition of the rocks, which in that 

 state, like those of Wales, are of a greyish-white colour. In Wales, 

 however, the included fragments, which alone may suffice to 

 characterize the whole series of Charnwood as belonging to grey- 

 wacke, have not yet been describedas occurring, though from the 

 very great similarity of its rocks and coarser slates to of those the 

 Forest, they may probably hereafter be discovered ; for in 

 Wales the fragments hitherto observed in its rocks appear to be 

 chiefly confined to a slaty substance, not unlike flinty slate, and 

 which is actually found in situ between layers of the rock itself; 

 the same substance, as well as the nodules which appear to be 

 contemporaneous with the rock, is likewise found in Charnwood 

 Forest. 



If, however, the characters of the rocks of some parts of 

 North Wales should hereafter decide them to be greywacke, 

 there are others in which the characters seem so absolutely 

 talcose, that it may be found difficult to assign the whole to one 

 common origin, and equally so to separate them, on account of 

 the close connexion of the whole as regards position and the 

 constant direction of the slaty cleavage through all the varieties. 

 In Wales this direction is about NE and SW, the slates being 

 either vertical, or dip at an angle of about 72° to the NW or 

 SE ; while in Charnwood Forest the upper edge of the slate 

 always runs about NW by W, and SE by E, dipping uniformly 

 about 72° a little to the east of N. 



Assuming the direction of the variously coloured layers so 

 obvious in many parts of Charnwood Forest, to be that of the 

 stratification, which, perhaps, will scarcely be doubted, and 

 which, as has already been said, differs in different parts of the 

 tract, it may be remarked that this has not been observed in the 

 same degree in North Wales, although it is sufficiently visible 

 near the summit of the Cleweth, a point but little inferior in 

 elevation to that of Snowdon itself. 



New Series, vol. mi. c 



