1824.] the Rocks of Mount Sorrel, fa. 1 1 



the various forms in which these substances appear. In some 

 instances, the chlorite, instead of being disseminated throu°h- 

 out the mass, is arranged in irregular layers, thus imparting a 

 schistose character to it(Windgate Hill, Great Bucks Hill, &c.) 



Near Swithland are several quarries of the slate just described, 

 one of which is estimated at 150 feet in length, and as much in 

 breadth and depth. In all the quarries the run of the ed°-e of 

 the slaty cleavage is, as before related, NW by W, and SEbyE, 

 the broad surface of the slate dipping about 72° towards the NE, 

 and it is to be remarked, that in each quarry, and particularly in 

 the largest, there is a run of the best slate, about 15 feet wide, 

 forming a kind of vein parallel with the direction of the cleavage, 

 and flanked on each side by an inferior kind of slate ; parallel 

 also to this vein of superior slates, is another vein (if so it may 

 be called) of a substance which is of a grey or greenish-grey 

 colour, of a granular appearance, and consisting apparently of 

 the imbedding substance or paste of the rocks of this district, in 

 which chlorite is abundantly disseminated in particles and nests, 

 and occasional specks of talc ; quartz, from its hardness, may 

 be concluded to be ah ingredient of the mass, but is too small 

 to be detected by the glass, and there is no appearance of 

 texture. 



Other instances in which this substance assumes a granular 

 appearance occur, and without any perceptible mineral imbedded 

 in it (Hangingstones, Beacon Hill, &c.) : sometimes it forms a 

 paste of a dull-green colour, which appears nearly or altogether 

 homogeneous, possessing a splintery fracture, and varying greatly 

 in hardness (above Whittle Hill quarry, High Swanmore, Short 

 Cliff Hill) ; sometimes it is so soft as to yield readily to the 

 knife ; and the quartz is so sparingly disseminated through it, 

 that although it slightly scratches window glass, the substance 

 itself is left upon it as a grey powder (Hone-stone of Whittle 

 Hill) ; in other instances, it is much harder, owing most proba- 

 bly to the presence of a greater proportion of quartz, but still so 

 minute as to escape the eye (Bird Hill, Beacon Hill, and other 

 places) ; these varieties are generally fissile ; as well as others 

 in which chlorite is perceptible as giving the greenish tint to the 

 slate; in others, the green colour is totally wanting; the sub- 

 stance has then a yellowish tinge with every appearance of 

 homogeneity, is frequently hard, sometimes so hard, owing to 

 the abundant dissemination of siliceous particles throughout the 

 mass, as to resist the knife, and it then assumes the aspect of 

 compact felspar, or of hornstone (Bird Hill, base of Windgate 

 Hill, 8cc.) ; but a substance of the same nature and degree of 

 hardness also occurs, which is considerably schistose, greatly 

 resembles flinty slate, is greenish, arising, as is visible by trans- 

 mitted light through thin fragments, from the presence of chlo- 

 rite often disposed in irregular lines (Morley Hill quarry). All 

 these varieties are more or less slaty, and the laminae have the 



