16 Messrs. W. Phillips and Kent on [Jan. 



single rock about eight feet high stands in the form of a doubly 

 oblique prism, of which only the base is beneath the surface. 



^Qx 



This prism is traversed by crevices, or by indications of them 

 marked by imperfect lines parallel to all its planes ; and so com- 

 plete has been the action of the elements in some parts of this 

 rock, that we succeeded in extricating from it some natural 

 fragments in the form of the rock itself. This rock consists of 

 bands of somewhat different colours lying parallel to the upper 

 plane, and dipping towards the E at an angle of 45° ; these 

 bands differ but little in character, being mostly of the more gra- 

 nular-looking varieties, and considerably hard. Close to this 

 rock are several others of less dimension, but of the same form, 

 and whose upper planes dip at the same angle. It remains to 

 be added that we fotnd the only cleavage practicable by mecha- 

 nical force, though somewhat obscure, is in this rock parallel to 

 the ordinary cleavage of the slaty rocks of the country, and, 

 therefore, parallel to one of the sides of the prism, visible in the 

 preceding sketch. This, however, is one among a multitude of 

 proofs visible in various parts of the forest, that although no 

 other cleavage is attainable by mechanical means than that 

 which has so often been alluded to, yet a long exposure to the 

 elements produces similar effects in another direction ; and 

 hence are to be observed in various places, rhombic prisms of 

 this rock, but the angles at which the planes meet, are by no 

 means constant, and where the rock is not banded, as it is in 

 the above instance, the upper plane is altogether wanting. 



In conclusion it may be observed, that although in several 

 instances (some of which have been quoted) these rocks 

 appeared to be stratified parallel to the cleavage plane — that is 

 to say, some of its varieties succeed each other in that direc- 

 tion, yet we are disposed to believe from examination, that the 

 stratification, which may be termed the order in which these rocks 

 were deposited, is in fact parallel to the variously coloured bands, 



