1824.] 



the Rocks of Mount Sorrel, fyc. 



15 



This rock, represented by the above sketch, is about 12 feet 

 high, and is constituted of alternate layers of green or greenish 

 rocks more or less slaty (SR), and of blue slates (S) ; the central 

 band consists, as do certain of the others, of some of the more 

 granular looking varieties of rock, alternating with that which has 

 already been described as greatly resembling a green jasper ; 

 there is no precise line of demarcation between them, nor does 

 there appear to be any schistose structure parallel with these 

 bands, except what is produced by long exposure to the atmo- 

 sphere, which acts of course differently on substances appa- 

 rently composed of very different materials, or, more accurately 

 speaking perhaps, of the same materials in very different propor- 

 tion, and consequent state of aggregation. The bands here, as 

 near the summit of the hill, dip to the S, but the angle differs ; 

 above it is 32°, here it is 45° ; the cleavage of the slates, how- 

 ever, which are interstratified with the rock, is in another direc- 

 tion, being perfectly consistent with that of the actual slates in 

 all other parts of the tract; namely, 72° to the NE; and it is 

 remarkable that the weathering of the rocks lying between the 

 slates has a tendency to separate them chiefly in the same 

 direction. 



The weathering of these rocks, however, when composed of 

 more uniform materials, is too striking in one or two cases to be 

 passed over in silence. The masses chiefly seen on the hill 

 termed the Hanging Rocks, have almost altogether the form of 

 tetrahedrons, from two to six or eight feet high resting on the 

 base, and having one plane constantly dipping towards the E at 

 an angle of 45 , and this plane is parallel to the variously 

 coloured bands of which the whole mass is constituted, and 

 which in some cases have separated by the action of the atmo- 

 sphere upon them. The other instance is on the summit of 

 Beacon Hill : here the action has been carried still further : a 



