282 MR. T. 0. BOS WORTH OX THE [June 191 2, 



' humps/ which commonly occur between hollows, are cross-sections 

 of the spurs which separate the gullies. 



The shapes of the buried hills are various : some are sharp 

 ridges, some roughl}' circular peaks, and some are more complicated. 

 A number of them are shown by contoured maps in the more 

 detailed paper which has been laid before the Leicester Literary & 

 Philosophical Society, and is being published as mentioned above : 

 of these. Pis. XXIII-XXYI are given here as examples. These 

 maps have been prepared by making measurements, from time 

 to time, around the quarries, of the levels wherever the Marl is 

 exposed in contact with its rocky floor. 



The rock-slopes found beneath the ITarl are usually very steep 

 and often precipitous. Sometimes slopes and cliffs are bared of 

 Marl to depths of 20 or 30 feet at a time, preparatory to blasting 

 operations (see PI. XIX, fig. 2). 



The character of the rock-surface beneath the Keuper depends 

 partly on the nature of the rock. 



The homogeneous granite and syenites usually present greatly 



worn surfaces. Thus at 

 Pig. 1. Mountsorrel occur the 



grooved and terraced 

 surfaces described by 

 Prof. Watts,^ and sur- 

 faces somewhat similar 

 are found on the Groby 

 syenite ; while the fine- 

 grained homogeneous 

 South Leicestershire sy- 

 enites are fretted into 

 more intricate shapes, 

 and are pitted and some- 

 what polished. Quite 

 a high polish was observed on the Xarborough (misprinted * Marl- 

 borough ' on the map, PI. XXII) syenite, which is mainly felsitic. 



An interesting example was found at Croft Quarry beneath 

 undisturbed Marl.^ The rock is divided into great blocks by 

 joint-cracks which have been widened out downwards. It is 

 suggested that this widening, which is most marked on the south 

 sides of the cracks, was caused by the action of dew. But, above a 

 certain level, the surface of the rock is fretted and the joint-cracks 

 widened upwards. This may have been caused by sand drift at a 

 time when the rock was buried up to this conspicuous limit. 



1 Eep. Brit. Assoc. (Dover 1899) p. 747 ; Geol. Mag. dec. 4, vol. yi (1899) 

 p. 508 ; ' The Geology of the Country near Leicester ' (Expl. of Sheet 156) Mem. 

 Geol. Surv. 1903, pi. i ; Geogr. Journ. vol. xxi fig. 12, facing p. 632. 



2 See Trans. Leicester Lit. & Pliil. Soc. vol. xii, pt. i (1908) fig. iii ; or Geol. 

 Mag. dec. 5, vol. v (1908) pi. xv, fig. 1. 



Outline Map of 

 Groby Village Quarry 



fl K 3Iile 3^2 Mile 

 I \ 1 



