332 STRATIGRAPHICAL GEOLOGY 



the north-west, while the thickness of marl increases in that direc- 

 tion. It is clear, therefore, that the materials of this breccia, as of 

 the main mass, came from the south and south-east. 



In Leicestershire there are a few small but interesting deposits 

 of Permian age, which have been carefully studied and described 

 by Dr. H. T. Brown 3 and Professor Bonney. 4 They consist of 

 grey breccias, grey sandstones, and red marls, not more than 60 

 feet thick in Leicester, but as much as 200 at Polesworth in 

 North Warwick. The breccias thicken to the south and the 

 marls to the north, and their thickness may originally have been 

 greater, as they are overlain unconformably by the Trias. The 

 pebbles in the breccias consist of the following kinds of rocks : 



(1) The larger number (about 60 per cent) are felspathic grits 

 or quartzites, derived from the Cambrian quartzites, but differing 

 slightly from those exposed at Hartshill. 



(2) Gritty slates from the same series, averaging 17 per cent. 



(3) Flinty slates and argillites, probably Charnwood rocks. 



(4) Volcanic rocks, some being felsites and andesites from the 

 pre-Cambrian (Caldecote) Series, some of a rock which may have 

 come from Charnwood, and diorites like those in the Cambrian 

 near Nuneaton. 



(5) Fragments of Carboniferous grits, ironstones, and hjematite ; 

 but pebbles o'f Carboniferous limestone are rare, except at Poles- 

 worth. 



In most of the exposed breccias over 80 per cent of the fragments 

 come from the Cambrian quartzite series, and Dr. Brown shows 

 that they have probably been derived from a buried ridge of these 

 rocks which underlies Market Bosworth and runs parallel to the 

 well-known Hartshill ridge. This buried ridge appears to be a 

 faulted anticline, and so exact is the parallelism between these 

 ridges and the principal faults of the Leicestershire coalfield that 

 they may safely be attributed to the same period of earth-movement. 

 These faults are known to be post- Carboniferous, and the iindis- 

 turbed way in which the breccias lie, bridging over the faults, 

 makes it very probable that they are of Permian age. 



The view that these are terrestrial deposits of early Permian age 

 will account for their proximity to the different set of deposits 

 near Nottingham which belong to a late epoch in Permian time. 



2. Devon and Somerset Area 



This area is taken next because its Permian rocks have a strong 

 resemblance to the Saxonian facies,and especially to the Eothliegende 

 of the Hunsruck district between Treves and Bingen, as pointed 



