PRECAREONIFEROTJS ROCKS OP CHARNWOOD FOREST. 769 



9. The series of exposures round Groby Lodge are cut off from all 

 hitherto described by syenite, which probably extends in a broad 

 belt from Cliff Hill by Markfield to Groby Pool, Sheet-Hedges Wood, 

 and Bradgate. This group of small ridges and knolls all consist of 

 fine slate, generally coloured purplish or green, sometimes reddish, 

 rarely and obscurely striped ; so that the dip is ascertained with 

 difficulty. The dips, so far as ascertained, look very irregular ; but we 

 think they may be combined so as to indicate a rolling of the strata. 

 Near Groby Lodge is a large quarry, where the rock is worked for 

 slabs and gateposts, the cleavage being too imperfect for roofing- 

 slate. The westernmost exposure is not marked on the map. It is 

 by the side of the lane leading to Markfield Field, about east 

 of Whittington Grange, and in nature resembles the rest, with an 

 apparent but uncertain N. dip. The small exposure by " Steward's- 

 Hay Spring " is a purplish quartzose grit, apparently containing a 

 few grains of magnetite. Under the microscope it is seen to be 

 formed of rounded and subangular quartz grains, with a few 

 resembling a subcrystalline slate set in a cement of similar aspect, 

 more or less stained with black iron oxide. Close to this, and just 

 within the wood, is a small quarry in syenite and an ashy slate re- 

 minding us of that in Bradgate- Stable Quarry. We could not decide 

 which of two sets of planes indicated the dip of the grit. The strike 

 of either, if protracted, leads to Groby Pool, on the north shore of 

 which (by the boathouse, about 30 yards from the last patch of 

 syenite) is a small outcrop of a very hard quartzose grit, which only 

 differs in appearance from this in being a shade finer. It seems to show 

 a very faint indication of a cleavage, striking W. 10° N., and is re- 

 markably like that of Swithland. Now, since both at Swithland and 

 here there are workable slates on the very outside of the country, and 

 both are underlain by a rather peculiar quartz-grit bed, it seems 

 highly probable that the slate and the grit in each place belong to 

 the same bed. If, however, the quartz grit of the Stable Quarry in 

 Bradgate be identical with these beds, as seems very probable, great 

 faulting must exist — a thing easily credible. To this point we shall 

 return hereafter. 



10. There is a rather remarkable isolated patch of rock at Sand- 

 hills Lodge. The lowest portions are indurated flinty slates, very 

 much jointed, dip uncertain. But a few yards higher is an old 

 quarry which consists of a mass of coarse, ashy, slightly brecciated 

 rock. It is bluish green, with small bits of dark green slate and 

 pink felsitic material, and is a little fibrous in texture, with surfaces 

 of a lustrous dark-green chloritoid mineral. This rock seems to 

 resemble that hereafter to be described at Kite Hill, near the 

 Monastery. The dip appears to be W.S.W., but undulating. Just 

 above the crest, and between this and the indurated slate mentioned 

 above, is a slate showing stripes very much contorted and dislocated, 

 and with a platy conchoidal cleavage or fracture. This looks at 

 first like a fragment; but examination seems to show that it is 

 interstratified with the coarse ash bed with a roughly southerly dip, 

 but that both have been squeezed together with great but irregular 

 force. 



