Vol. 6S.^ KETJPEK MAELS ABOUND CHAENAVOOD. 283 



The evidence of intense wearing must not be sought for inside 

 a quarry, for the natural rock-slope is facing away from the observer ; 

 but it may be found outside the quarry, wherever the marl is 

 being dug away from the rock preparatory to extension of the 

 working. 



In the cleaved rocks of Bardon and Shepshed, etc., and in the 

 slates of the Brand Series the surfaces are more angular. 



Cross-sections of gullies are common in most of the quarries. 

 In the homogeneous granite and syenites they are often U-shaped, 

 but in the cleaved rocks they are V-shaped or trough- shaped. 



Many of the gullies have been determined by cleavage, fault- 

 lines, or master-joints.^ 



Condition of the Buried Rocks. 



Effect of Quaternary Climate. 



The igneous rocks exposed to the present climate are intensely 

 weathered. For instance, at Huncote, and also at Enderby, the 

 South Leicestershire ' syenite ' shows spheroidal weathering even 

 to the bottom of the quarries ; and the topmost 12 feet of rock has 

 decayed in situ into loose grit, in which colonies of sand-martins 

 make their nests. At Mountsorrel exposed granite was observed 

 similarly decomposed (oj). supra cit. fig. i). 



Apparently, similar weathering occurred before or during the 

 Glacial Period : for, in some cases, the lowest portion of the drift 

 clays resting on the igneous rocks is composed largely of scraps of 

 decayed rock. 



Effect of Triassic Climate. 



In marked contrast is the state of the same rocks beneath the 

 Keuper Marl : for, righb up to their very surface, these rocks are in 

 sound condition. At Mountsorrel, Croft, Earl Shilton, and other 

 localities, the best stone is that beneath the marl, and it appears 

 equally good from the bottom of the quarry to the top. 



For this reason many old surface-workings are abandoned, and 

 the quarries are being extended and new ones opened to win the 

 rock from beneath the Keuper Marl. 



Similarly, the derived stones found in marl, whether worn or 

 angular, are perfectly sound, and can be sent to the mills along 

 with the best quarried stone. 



Breccias, Stone Bands, etc. 



In the immediate neighbourhood of the Charnian rocks, as seen 

 in the quarries, the marls include a large quantity of stones, both 

 small and great. It is remarkable that, in all cases, they are 



1 See Trans. Leicester Lit. & Phil. Soc. vol, xii, pt. i (1908) fig. v. 



Q. J. G. S. No. 270. X 



