212 W. J. HARRISON ON THE OCCURRENCE 



24. On the Occurrence of the Rhjstic Beds in Leicestershire. 

 By Wm. J. Harrison, Esq., F.G.S., Curator of the Town 

 Museum, Leicester. (Read March 8, 1876.) 



Good inland sections, exhibiting the junction of the Triassic and 

 Liassic beds, are rather scarce in this country. I wish, therefore, 

 to describe an exposure of the Rhaetic beds near this town, which 

 is of interest as proving the continuity of that formation and the 

 remarkable persistence of lithological conditions in its strata ; whilst 

 the occurrence of some new species of fossils shows that our know- 

 ledge of the life of that period is, as yet, very incomplete. 



These Rhaetic beds are to be seen in three brick-pits situated at 

 the northern extremity of the Spinney Hills, a low range forming 

 the eastern boundary of the town of Leicester and the Soar valley 

 (fig. 2). 



The Rhaetics form a capping to the hills at this northern end ; but 

 southwards, as the ridge rises, they are overlain by a thick covering 

 of drift to the depth of at least 20 or 30 feet. 



Eastwards the upper members have been denuded by a little 

 stream, the Willow Brook, although the lowest bed (the Grey Marl) 

 is nearly, but not quite, continuous right across to Crown Hill, 

 where Lower Lias beds (yellow fucoidal limestones) first put in an 

 appearance (see fig. 2). 



The floor of the brick-pits just mentioned is about 10 feet deep in 

 red Upper Keuper Marls. Descending sections in neighbouring 

 pits and in the railway-cutting near the station show an alterna- 

 tion of Red, Grey, and Blue Marls to a depth of from 80 to 100 feet. 

 It is noticeable that the relative thickness of the red bands becomes 

 less as we approach the top. Selenitic crystals and salt pseudo- 

 morphs occur in these beds ; but they have as yet exhibited no traces 

 of life. A thick nodular band of gypsum occurs about 60 feet down. 



Close to the eastern foot of the Spinney Hills a boring for coal has 

 reached the depth of 741 feet (fig. 2). This commences just below the 

 Rhaetic Grey Marl, and passes through 690 feet of Keuper Red Marls 

 containing much fibrous gypsum, and in the lower part thick red 

 clays, and then enters a bed of sandstone, through which it is now 

 passing. It would thus seem probable that these Triassic beds 

 thicken in this direction ; and as we are receding from Cbarnwood 

 Forest (a Triassic island), this would be a likely consequence. Of 

 the 51 feet of Lower Keuper Sandstone, the first 20 feet is described 

 by Mr. J. A. Bosworth, F.G.S., the engineer, as a perfect quicksand, 

 no solid cores being obtained. At Hinckley, twelve miles to the 

 S.W., the Red Marls are of the same thickness, as proved by a 

 borehole for water, of which a good supply was obtained, but too 

 much impregnated with mineral matters for use ; the same thickness 

 of marl was also proved at Rugby, where the water was equally bad. 



In the brick-pits the Rhaetics are seen to rise nearly vertically for 

 about 30 feet above the Red Marl, to which their stratification is 



