52 SCIENTIFIC SURVEY OF NOTTINGHAM AND DISTRICT 



diminished to only 40 feet. The form of the rock mass suggests that of 

 a supra-terrestrial delta with its axis pointing to the north-west as the 

 direction of origin of the matrial. 



The top surface of the Bunter is wind eroded and carries irregular 

 heaps of loose pebbles, many of which are facetted. Facetted stones 

 have also been found in the bottommost beds of the Bunter where it 

 rests upon the old landsurface, as for example at Dale. 



The Bunter outcrop occupies one quarter of the area of Nottingham- 

 shire and is an invaluable source of water supply for all towns within a 

 reasonable distance of its boundaries. 



The Keuper Basement Beds in the vicinity of the city of Nottingham 

 vary in thickness up to 16 feet. Here they consist of sandstone having 

 the same texture as the conglomerate but almost white in colour. In this 

 state they appear to be a marginal or shore facies for they change as 

 they pass eastward into finer grained sandstones of light grey colour 

 interbedded with red marls, having a total thickness, a few miles to the 

 east, of 40 feet. 



The Keuper Sandstone has a clearly defined base marked by the pre- 

 sence of a thin conglomerate — the Keuper conglomerate. This passes up 

 into a bed of yellowish sandstone some 3 feet thick. This division of 

 the Keuper is 100 feet thick and is made up of clusters of interbedded 

 sandstones and marls from 20 to 30 feet thick separated by a correspond- 

 ing thickness of red marls. The sandstone belts exhibit a marked rhyth- 

 mical repetition from thick layer of sandstone through thinner beds with 

 beds of marl to thicker beds of marl. The surfaces of the sandstone 

 layers vary in character and exhibit ripple marks, rainprints, suncracks 

 and footprints. On three occasions they have yielded fish remains be- 

 longing to species of Semionotus and Woodthorpea. 



The Keuper Marl has a thickness of 600 feet and consists mainly of 

 red marl with occasional belts of thinly bedded fine grained sandstone 

 known as ' skerry '. The marl varies in character slightly. Some layers 

 are compact and appear to show no lamination. Others strikingly re- 

 semble varve clays in all but colour. The skerry often shows curly bed- 

 ding but sometimes the surfaces may be ripple marked or may bear 

 crowds of salt pseudomorphs. Toward the top of the Keuper marl 

 gypsum appears in sufficient quantity to be mined. In its uppermost 

 portions the marl becomes green and is then known as the Tea-green 

 marls. 



H.H.S. 



The Jurassic Beds 



Jurassic beds outcrop over a broad belt in the East Midlands. The 

 greater part of the sequence is present, and only the Portland and Purbeck 

 beds do not occur in this area. 



The strike of the beds is N.N.W. in the north of Lincolnshire, N. 

 in mid and south Lincolnshire, and changes to S.W. in Leicestershire 

 and Northamptonshire. The alternation of hard and soft rocks, dipping 

 gently eastwards, has given rise to a series of escarpments. Thus the 

 marlstone gives rise to the Belvoir escarpment, and to the high ground 



