A. R. Horwood — Upper Trias of Leicestershire. 21 



spilites may be mentioued. About a mile north of the point where 

 the analysed specimen occurred spilite is found associated with coral 

 limestone containing fragments of recognizable coral. The micro- 

 scopical structure has every indication of rapid cooling.^ This seems 

 to show clearly that spilite lava has flooded over a living coral reef 

 and is not thei'efore necessarily a deep-sea lava. Radiolarian beds 

 occur above and below this curious association of lava and limestone. 

 The Sedgwick Museum, Cambridge. 



VII. — The TJppek Trias of Leicestershire. 



By A. E. Horwood.^ 



Part I. 



1. General Description of the District. 



2. Summary of Previous Work. 



3. Stratigraphy of the District. 



Part II deals with Physiography, Tectonics, Petrography and Lithology , 

 Palaeontology, Economies and Water Supply, Sections, Bibliography, 

 Appendix. 



1. General Description of the District. 



THE Upper Trias of Leicestershire as a whole occupies the western 

 half of the county, being bounded on the east more or less by the 

 Soar Yalley, following the strike (as a subsequent in part of its 

 course up to its junction with the Wreake). In fact, it is on the 

 eastern boundary near the outcrop that the beds are mainly best 

 exposed, the region to the west south of the coal-field around which 

 it mantles being little developed and presenting fewer exposures. 



The area under consideration is not less than 300 square miles in 

 extent. It reaches from the Ptiver Trent, the northern boundary, to 

 the Watling Street in the south, and from the eastern boundary, 

 roughly coinciding with the Soar Valley and Midland Hallway, to the 

 western boundaries of the county, adjoining contiguous tracts of 

 Trias in Warwickshire and Staffordshire. There are two main 

 outcrops within this area of older rocks, the Carboniferous and 

 PermiaH rocks, with Bunter in the north-west, between Moira and 

 Ashby-de-la-Zouch, and the Charnian range of hills of Pre-Cambrian 

 rocks 5 miles north-west of Leicester. Outlying outcrops of 

 syenite between Hinckley and Leicester in the south, and of granite 

 at Mountsorrel, Buddon Wood, etc., north-west of Leicester, also 

 rise up as knolls in the Red Marl area. Elsewhere glacial deposits 

 cover the Trias, especially south and east of Charnwood. 



The Lower Keuper follows the Permian and Bunter outcrops on 

 three sides of the Ashby Coal-field, and on the north side encircles 

 the Charnwood Hills, where it rises to some height at Longcliffe and 

 other points, and forms marked features elsewhere. 



The Bed Marl occupies the largest portion of this area. It forms 

 the flat plain, little diversified except by syenitic knolls, such as 



^ W. N. Benson, "Preliminary Account of the Geology of the Nundle 

 District, N.S.W. " : Eeport of the Australian Association for the Advancement 

 of Science, 1911, p. 101. 



- Aided by a grant from the Government Grant Committee of the Eoyal 

 Society. 



