A HISTORY OF NOTTINGHAMSHIRE 



THE MAGNESIAN LIMESTONE is the most important, widespread and 

 characteristic of the Permian deposits. In the form most commonly 

 seen near Nottingham, where it is largely used as a building stone, it 

 consists of a number of rhombohedral crystals of dolomite with inter- 

 vening hollow spaces. It is of a peculiar brownish yellow colour, due 

 to oxide of iron. It yields about half its weight of magnesium sulphate 

 (Epsom salts), but it has not hitherto been used commercially as is done 

 near Sutherland. * Sulphate of baryta is a very abundant mineral in many 

 parts of the formation ' in crystalline nodules and veins in the freestone 

 beds of Mansfield and at Pleasley (Sedgwick). The limestone is every- 

 where water bearing and supplies many wells, as in the Leen valley, but 

 the water is naturally hard, as is shown by the tufa near Annesley Park 

 springs already referred to. It may occur in fairly massive beds, 8 10 

 inches thick, in which case it is used for building, or in large flaggy beds 

 with irregular rough surfaces and greenish marl interstices. 



The crystalline structure is not original, but has been produced by 

 later alterations, for it is accompanied by the breaking up of the surface 

 of any individual stratum and the formation of curvilinear cracks in the 

 mass, as seen in Grives Wood quarries. It is possible that this crystal- 

 lization has destroyed some of the organic remains, but more probably 

 they were never abundant, since when they are found they occur mostly 

 as hollow casts in definite layers, differing in no other respect from the 

 neighbouring barren ones. Such fossiliferous layers, with casts of Schi- 

 zodus and Bakeivellia, are seen in the limestone quarries at Bulwell, in the 

 old quarries at Beauvale near Greasley, in Grives Wood, whence Scbizodus 

 obscurus and plates of Chiton have been recorded ' ; and in a quarry near 

 Shireoaks, which has yielded fine examples of Productus borridus? found 

 also in the Thurgarton boring. 3 



In the southern part of the county the maximum thickness is only 30 

 feet, yet the limestone extends over a considerable area in the Leen valley. 

 This is due to the fact that the dip is very low, 2-3 to the east, and 

 the overlying clay is very easily removed by denudation. There is, how- 

 ever, a very curious anticlinal in which the overlying rocks concur near 

 Middle Mill, east of Hucknall Torkard. It is exposed in a small quarry, 

 of which it occupies the entire end, but there is no surface indication of 

 its existence in the flat marshy field composed of the overlying marls. 

 Two other similar small anticlinals have been noted in the neighbourhood 

 (Shipman). 



The most south-westerly point at which the Magnesian Limestone 

 has been observed is near Bobbers' Mill, Radford, where it is a coarse 

 brecciated rock followed by a grit (Wilson). At Strelley it is sandy. It 

 probably never extended much more westerly than its present boundary, 

 as no outlier is known more than 1 1 miles from its escarpment. Nearly 

 as far north as Mansfield it remains fairly constant in thickness and 

 character, but at New Mill, a mile south of that town, it is found to 



1 King, Permian Fossils (Pal. Soc.) * Tylden Wright in White's Worksop. 



8 ' Summary of Progress for 1899.' 

 16 



