Vol. 67.] PERMIAN TO THE TRIAS IN NOTTINGHAMSHIRE. 87 



the minor details, such as the position of the sandy bands, vary 

 within the limits of a single clay-pit. 



From Nottingham to Mansfield the Permian Marl has been 

 followed continuously as a thin bed of silty clay separating the 

 Bunter from the Magtiesian Limestone. At Mansfield, however, the 

 Marl has disappeared, and the Bunter rests directly upon the Lime- 

 stone. This fact, at first sight, seems to offer support to the theory 

 of an unconformity between the Permian and the Bunter ; but a 

 careful examination of the district offers a different interpretation, 

 namely, that the Permian Marl has locally changed its character, 

 and become sandrock indistinguishable from the Bunter above. 



The phenomenon of the somewhat sudden disappearance of the 

 Marl at Mansfield does not stand alone. In the same district the 

 Magnesian Limestone, which has also remained fairly constant in 

 character and thickness from near Nottingham to Sutton-in- 

 Ashfield, thickens greatly (at Bestwood x the Magnesian Limestone 

 is but 30 feet thick, while at Sherwood Colliery, Mansfield, it is 

 236 feet), and is divisible into different types of rock. The upper 

 part becomes so sandy, that at Mansfield it forms the well-known 

 building-stones known as the White and Bed Sandstones. 

 These ' sandstones '" are really composed of about equal parts of 

 sand and dolomitic cement, 2 the red differing from the white merely 

 in the presence of ferric oxide. 



At Messrs. Lindley's White Sandstone Quarry (south of the eastern 

 angle of the triangular area marked off by railways on the map) 

 the Marl above the ' sandstone ' is worked for bricks. Near the 

 western end of the section the Marl is about 18 feet thick, with green 

 sandy bands ; but, as the eastern end of the workings is approached, 

 the total thickness of the Marl decreases considerably, while a sand- 

 stone makes its appearance in it and grows rapidly in importance. 

 Portions of the remaining Marl also become sandy, until at the 

 eastern extremity of the section it has become : — 



Tliickness in feet. 

 Pig. 3. — Section at Messrs. Lwdleifs Sandy pebbly soil, and sand, 

 White Sandstone Quarry, Mansfield. • perhaps slightly slipped ... 3 



T-rv- ., ■ ..■■..-.. -..-.-.•; : :. v . v: ^ v ;:/;.. v: .:^ ^== Ked marl, the lower part sandy 3 



;."--■ --_-_. :__: Fine-grained sandrock, leaden- 



3 :'•'.'. ■" ■•-• .v. / -".': •■•■•.•■ ■„■■■.•■'■.■■■■ —— ■.-■—-.-■-. r:~:~-*7Z7i 2 



grey when broken, weathering 

 ^i^^jv^ r ~r_'"~ ~"!t^3 yellowish 2 



Eed marl 4 



Marly sandrock (intermediate 



[The sandy development of the Lower Mag- in character) 1 



nesian Limestone (b) is overlain sharply by 



Permian Middle Marls, in which sandstone Undulating floor of dolomitic 



bands (a) develop towards the east (left).] sandstone (e 2 ). 



1 Gh W. Lamplugh & others, 1908, p. 28. 



2 W. T. Eveline, 1879, pp. 10 & 12. 



