8 Messrs. W '. Phillips and Kent on [Jan. 



reposing on the rock of the quarry, and bounded by it on each 

 side ; we could not, however, perceive the actual junction. 



There are two dykes of which the substances much resemble 

 each other, except that in one part of one of them the rock has 



freatly the external characters and appearance of a fine-grained 

 asalt. Just beside the road that divides the line of quarries 

 which overhang Mount Sorrel, we perceived among other stones 

 broken up for the repair of the roads, many fragments of a bluish 

 hue ; and on inquiries respecting the place from which they 

 were taken, a vein running nearly N and S, and about a foot 

 in thickness, was described to us as existing beneath the rubbish 

 just where the road turns to the left round the house inhabited 

 by a clergyman whose name we did not learn, but on the oppo- 

 site side of the road. We, therefore, did not see the dyke in 

 question. The rock has, in no inconsiderable degree, the aspect 

 of agranular basalt, and .though considerably hard, it yields to 

 pressure with the knife a grey powder pretty readily. The only 

 discernible substances in it are extremely minute and slender 

 crystals of transparent felspar, and sometimes cubic, sometimes 

 octohedral crystals of magnetic iron pyrites, together with occa- 

 sional specks of a yellowish-white substance which appears to 

 be laminated, but does not effervesce on the application of 

 diluted muriatic acid. The base or imbedding substance is not 

 sufficiently characterized to enable us to decide upon its nature; 

 it is, however, considerably soft, and when reduced to thin frag- 

 ments is translucent, of a slightly brownish hue, and contains 

 extremely minute specks of a dark-green colour. It seems, how- 

 ever, intimately connected with that of the mass constituting apart 

 of the dyke about to be described. This dyke is situated in the 

 small quarry called Simpson's Pit, in a rock perfectly resembling 

 that of Mount Sorrel, and about a mile SW of the town, at the 

 head of Rothley Plain. It appears to run through the mound in 

 which the quarry is situated nearly due N and S, is visible for 

 about 20 feet in height, is six feet wide at the lowest visible 

 place, and somewhat narrower at the surface, is nearly perpen- 

 dicular to the horizon, has very determinate walls, and reappears 

 about one-fourth of a mile SW in a field occupied by the landlord 

 of the Crown Inn at Mount Sorrel. The substance of this dyke 

 as it appears in the quarry, is of a bluish cast, yields readily to 

 the knife a grey powder, but is translucent in thin pieces, exhi- 

 biting, by the assistance of the glass, a multitude of dark specks 

 which appear occasionally to tinge the mass of a green colour ; 

 it scratches glass feebly (a circumstance not anticipated from 

 the use of the knife, and which may be owing to the presence 

 here and there of minute and slender crystals of felspar, or of 

 quartz too finely intermixed for observation), but its substance is 

 left on the glass. The mass itself has somewhat the aspect of 

 steatite, an aspect which is not to be observed where the dyke 

 reappears below : here it very greatly resembles a granular 



