50 SCIENTIFIC SURVEY OF NOTTINGHAM AND DISTRICT 



Permian and Trias 



The following subdivisions of these systems may be recognised in this 

 area : — 



Trias. 

 Permian Keuper. 



Marl. Mart. 



Magnesian Limestone. Sandstone. 



Marl Slates. Basement Beds. 



Breccia. Bunter. 



Conglomerate. 

 Sandstone. 

 Towards the close of the Coal Measure period, earth movements took 

 place which resulted in the conversion of this area along with the rest of 

 the country into dry land, and the establishment of an elongated dome- 

 like uplift in the region of North Derbyshire, and of less prominent folds 

 trending from north-west to south-east. These folds defined the western 

 and southern limits of the great synclinal basin of the Derbyshire and 

 Nottinghamshire coalfield. At the same time extensive denudation took 

 place and produced a varied landscape with limestone uplands, millstone 

 grit and coal measure sandstone scarps separated by broad valleys in the 

 belts of shale and clay. 



It was upon this very diversified surface that the Permian and Triassic 

 rocks were laid down, a fact which accounts for innumerable idiosyn- 

 cracies in the form and distribution of the outcrops of the latter. 



The Permian 



The Permian rocks are exposed in the northern outskirts of the city, 

 where they have a total thickness of about 60 feet. 



The unconformity which they make with the underlying Coal Measures 

 is emphasised by the presence of a layer of breccia at the base. This has 

 a maximum thickness of about 8 feet near to Mansfield. From thence 

 it spreads out in fan fashion towards the north, east and south thinning 

 out as it does so until in a distance of about fifteen miles it is represented 

 by only a coarse grit. 



The Marlslates are thinly bedded earthy magnesian limestones separated 

 by bands of shale, and sometimes crowded with very fragmentary plant 

 remains. The classic exposure in the Kimberley railway cutting which 

 was first described by Edward Wilson is still the best place to see these 

 rocks. 



The magnesian limestone is abundantly exposed in the quarries at 

 Bulwell on the northern side of Nottingham. It is made up of clearly 

 defined beds of various thicknesses. Unlike the rock as seen near Mans- 

 field, where it is compact and fine grained, it here consists of dolomite 

 crystals which are large enough to give it the appearance of a coarse 

 sandstone. At the outcrop recognisable fossil are rare, but in the boring 

 further east brachiopods, bryozoa, ostracods, and encrinite ossicles have 

 been found. 



The Permian marl consists of a deep red or chocolate coloured marl 



