T. 0. Bosu'orth — Origin of Tipper Keiiper, Leicestershire. 353 



Y. — The Oeigin of the TJppee, Kedpee of Leicesxershike.' 



By T. 0. BoswoRTH, B.A., B.Sc, F.G.S. 



(PLATES XV AND XVI.) 



n^HE following o"bservatioiis on the Upper Keuper are mainly from 

 JL the Charnwoocl district, wherein the relations of the Keuper to 

 the older rock beneath are easily studied. The observations are 

 arranged under three heads. 



1. Condition of the Rocks heneath the Keuper. — For the purpose of 

 contrast the extensive weathering produced by our present moist 

 climate may be first mentioned. This is well seen at Mountsorrel 

 in the section on the east side of the main quarry. Here the granite 

 has been denuded of its Keuper covering and has been exposed to the 

 existing climate. It is disintegrated down to several feet below the 

 surface, and is weathered to a considerable depth. Another good 

 example may be seen at Huncote Quarry, where the South Leicester- 

 shire granite is so decomposed that the sand-martins nest in it. 

 Spheroidal weathering occurs here. At Enderby also the Ketiper 

 has been removed by denudation, and spheroidal weathering is seen to 

 a depth of 50 feet. 



The Coal-measure climate also had a destructive action on these 

 rocks. I know of no section showing Coal-measures deposited on 

 Charnian rocks, but in 1904 I was able to watch boring 

 operations near Peckleton in search of coal. Eeneath the Coal- 

 measures, at a depth of some 200 yards, syenite of South Leicestershire 

 type was reached. About 45 feet of this were pierced, all of which 

 was intensely weathered, resembling the South Leicestershire rocks 

 where exposed to this climate. 



In marked contrast is the condition of these rocks where they are 

 overlain by Keuper. Eveiywhere beneath the marl the Charnian 

 rocks are in sound condition right up to the very surface and often 

 indistinguishable from the best stone at the bottom of the quarries. 

 Indeed, the best stone is usually quarried from beneath the Keuper, 

 and older workings in the surface rocks have been abandoned. From 

 what I have seen in the Mendips and South Wales I believe the 

 same surface freshness occurs in the Carboniferous rocks under the 

 Keuper. This remarkable freshness suggests that, while the Charnian 

 Hills were being buried by the Keuper deposits, a desert climate 

 prevailed. 



2. The Surface Features of the Roch leneath the Keuper. — It has 

 been shown by Professor "Watts that the subaerial features of the 

 buried Charnian Hills are very perfectly preserved, with peaks, 

 pinnacles, and precipitous slopes intact. Where the Keuper rests 

 on massive homogeneous igneous rocks, their surfaces are generally 

 smoothed, fretted, and curiously carved. Beautiful examples of wind- 

 worn rocks at Mountsorrel have been described by Professor Watts. 

 But in many other places also there are surfaces highly suggestive of 

 wind erosion, as at Croft, Sapcote, Groby, etc. They are usually 



1 Reprinted by permission from Transactions of the Leicester Literary and 

 Philosophical Society, vol. xii, part 1, 1908, pp. 28-34. 



DECADE V. VOL. T. — NO. VII. 23 



