[ 220 ] 

 XXII. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from vol. xxi. p. 696.] 



December 21st, 1910.— Prof. W. W. Watts, Sc.D., M.Sc, F.R.S., 

 President, in the Chair. 



r PHE following communication was read : — 



' The Relationship of the Permian to the Trias in Notting- 

 hamshire.' By Eobert Lionel Sherlock, B.Sc, A.R.C.Sc, F.G.S. 



In South Nottinghamshire the Permo-Trias consists of the 

 following divisions : — 



f Maria. 

 1 Water 



1 Waterstones. 



Bunter I Pebble Beds. 



\ Lower Mottled Sandstone. 



| Middle Marl. 



Permian < Lower Magnesian Limestone. 



I Marl Slates and Breccia locally. 



The conformability or unconformability of the Bunter to the- 

 Permian has been much discussed, but it is generally considered 

 that there is a small unconformity between them. The evidence 

 for this is the appearance of an Upper Magnesian Limestone, and 

 locally an Upper Marl, between the Middle Marl and the Bunter, as 

 the beds are followed northwards, so that the Bunter appears to 

 overlap the Permian divisions from north to south. 



In this paper, a section on the Great Central Railway, near 

 Annesley, is described, which shows a gradual passage from the 

 Middle Marl into the Lower Mottled Sandstone. Detailed mapping 

 on the 6-inch scale between Nottingham and Market Warsop has 

 confirmed this conclusion. 



From Nottingham to Mansfield the Middle Marl retains a uniform 

 character and thickness, but at Mansfield it is apparently absent, 

 and the Bunter has been thought to overlap it and rest directly on 

 the Lower Magnesian Limestone. At the same place the limestone 

 becomes very sandy, forming the Mansfield Sandstone. It is shown 

 that these two phenomena can be best explained by supposing that 

 a river deposited a sandbar at Mansfield during Permian times, so 

 that the limestone was replaced by sandstone, as was also, later, 

 the Middle Marl. The sandy representative of the Middle Marl 

 has been mistaken for Bunter, and so given rise to the appearance 

 of an overlap. 



North of Mansfield the Middle Marl becomes normal again. 

 Near Cuckney the Upper Magnesian Limestone first appears as a 

 very thin bed, and evidence is brought forward to show that the 

 limestone arises as thin lenticular bands in the Passage-Bed, which 

 develop northwards into a definite bed. In precisely the same way, 



