356 T. 0. Bosicorth — Origin of Upper Keuper, Leicestershire. 



All the material in the Keuper which has so far been mentioned is 

 of purely local origin ; and the screes, breccias, stone bands, and the 

 grit in the marl are entirely derived from the rocks which they 

 surround. Thus at !Narborough these are all of the peculiar 

 Narborough stone ; at Mountsorrel they are all granite fragments ; at 

 Swithland they are chips of slate, and so on. Nowhere is there any 

 mixture such as would occur in a beach, nor any evidence of shore 

 drift. In this matter the Keuper breccias differ greatly from those of 

 Permian age. Traced away from the hills the marl soon becomes free 

 from grit, and no coarse local detritus seems to have travelled far. 

 But at Woodhouse in a green band there is fine grit which can just be 

 recognised as granite from ^Mountsorrel, two miles distant. Also at 

 Swannington in marls low down in the Keuper there are sand beds 

 with scraps of slate and quartz which must have travelled about 

 1-^ miles. 



Of the normal Keuper marl there are many varieties. At Sileby 

 both the green and the red beds are sandy, but more usually the red 

 marl is of very fine texture and breaks with conchoidal fracture. 

 Sometimes this has a kind of nodular structure and shows the 

 bedding, and more rarely true laminated beds occur. The colour also 

 varies greatly. 



All the e%-idence of water action I have seen is confined to the 

 green bands in the Keuper, and this evidence points only to shallow 

 streams and salt pools. These green bands always contain quartz 

 sand, and it is my experience that when suitably weathered they 

 almost invariably show ripple-marks, and salt pseudomorphs which 

 are sometimes clustered along the crests of the ripples. The ripple- 

 marks vary greatly in size and character. If they are due to waves 

 controlled by 'the wind they may indicate its direction.^ For example, 

 at Nottingham they strike N. 20° W., and at Gipsy Lane, near 

 Leicester, they strike N. 40° W. But I have seen them striking 

 in different directions in layers of the same green bed only half an 

 inch apart. 



Upper Keuper Sandstone occurs in lenticular beds at various 

 horizons. It is usually grey and coarse. Near Leicester at the 

 Dane Hills it is nearly 20 feet thick and is very uniformly false- 

 bedded from the south-west. Estheria and fish-scales and fragmentary 

 plant-remains lie on the false-bedding planes, which dip at 30 degrees. 

 Yery similar beds occur in Warwickshire and Worcestershire. Beds of 

 similar sand dip steeply away from the Charnian inliers of Enderby, 

 Croft, and Stoney Stanton, and they contain nuggets of the local rocks. 

 Some beds consist of almost spherical grains and are apparently desert 

 sand. Rounded grains are also plentiful in the marl, and at the base 

 of the marl in South Leicestershire, resting upon the worn rock 

 surfaces. In South Leicestershire there are no quartz rocks from 

 which these coarse sands could be derived. Along the north and 

 north-east boundaries of Charnwood, the sands are finer. 



The heavy minerals also point to a distant source for the material. 



1 The author is collecting data, and would be greatly obliged for any information 

 as to strike of ripple-marks. 



