PRECARBONIFEROUS ROCKS OF CHARNWOOD FOREST. 229 



rock emerges from the Trias, forming the conspicuous eminence 

 of Croft Hill. There are large quarries near the villages of Hun- 

 cote and Croft. In the former, the usual irregular surfaces, with 

 syenite boulders in the base of the overlying Trias, are well exhi- 

 bited. One set of master-joints, called, locally, " slithers," is very 

 conspicuous in the pit ; and another parallel and closer set, oblique 

 to these, gives a kind of bedded appearance to the rock. This has 

 a general resemblance to slightly weathered specimens from En- 

 derby, but is rather more distinctly crystalline in texture. Under 

 the microscope, this apparent difference is shown to have a real 

 existence, the rock being distinctly crystalline-granular. Through-, 

 out the slide, though the rock is much decomposed, quartz (some of 

 it probably of secondary formation), felspar, and a green hornblendic 

 mineral are visible. A good deal of the last mineral, however, is 

 not hornblende (though probably a pseudomorph after it or biotite), 

 but the fibrous mineral already noticed. The felspar is both ortho- 

 clase and plagioclase, but the latter is quite as abundant as the 

 former. Magnetite and the usual decomposition products are pre- 

 sent*. There are occasional slight indications of a graphic struc- 

 ture. The rock, then, is intermediate in character between the 

 syenites and diorites ; but, on the whole, it will probably be best to 

 rank it among the former, and with the quartziferous varieties. 



The rock in the Croft quarries is macroscopically undistinguishable 

 from the last. There are here interesting sections of Boulder Clay 

 resting in an excavation in the Keuper, which overlies the syenite 

 in the outer part of the pit. The rock is also exposed in the village 

 of Croft, and there are some small quarries just outside that place, 

 across the brook. It appears everywhere of the same general 

 character. 



The syenite at Stony Stanton also forms an eminence on which 

 the village is built. We examined a large quarry at the entrance. 

 The rock here exhibits very conspicuous master-joints at intervals 

 of four or five yards, inclined at a considerable angle to the horizon, 

 more uniform and regularly parallel than in any of the other pits. 

 It is a little redder in colour than that of Croft Hill or Lower En- 

 derby, and rather intermediate in texture. The microscopic struc- 

 ture does not differ much from the last, except that there is more 

 hornblende, and a still nearer approach to the graphic structure. 

 There is also a little more quartz. The felspar is generally altered, 

 being replaced by the usual pseudomorphs, but both orthoclase 

 and plagioclase are present. The rock, then, may be classed with 

 the last described. 



In the Sapcote massif several pits are opened : most of these are 

 in the S.E. part, on each side of the Narborough and Hinckley 

 road. The easternmost of these (north of the road) is at present 

 of no great size ; the rock exhibited two rather well-marked sets 

 of master-joints, dipping respectively N.W. and S.S.E., but nothing 



* We have observed many of the phenomena described by MM. Poussin and 

 Renard in their admirable memoir ' Sur les roches plutonieunes de la Belgique,' 

 &c. pp. 28-32. 



