﻿W. T. Aveline — Magnesian Limestone 8f New Red of Notts. 155 



a. margin of valve; h. shell exhibiting prismatic structure; c. c. pallial 

 Cfeca penetrating ditto ; d. great pallial sinus ; e. marginal vessels ; /. outer 

 lamina of mantle ; g. external reticulated layer of ditto, in which the pallial 

 ca3ca take their origin ; /*. homogeneous layer of other lamina ; i. inner 

 lamina of mantle ; j. epithelium ; k. h. membrane lining pallial sinus ; 

 ou inner ditto ; o. marginal fold ; p. one of the setiE ; g. follicle of ditto ; 

 r. prolongation of glandular matter of follicle ; s. marginal muscles ; 

 t. extreme pallial margin. 



[Plates IX. and X. will appear in our next Number.) 



II. — The Magnesian Limestone and New Eed Sandstone in the 

 Neighbourhood of Nottingham. 



By W. T. Aveline, F.G.S., 

 Of the Geological Survey of England and "Wales. 



SINCE the Government Geological Survey of tlie country around 

 Nottingham was made in the year 1859, and the Explanation 

 on the Geological Map Quarter-sheet 71 N.E. was written in 1861, 

 papers by local geologists have been written, stating that in the 

 neighbourhood of Nottingham a perfect conformity existed between 

 the Magnesian Limestone and the New Eed Sandstone. This being 

 totally at variance with conclusions I came to when I surveyed that 

 country, I have been for some time past desirous to say a word on 

 the subject, but being deeply occupied with the old rocks of the Lake 

 district, I have put it off from time to time. I felt little doubt in my 

 mind, when surveying the neighbourhood of Nottingham, that there 

 was a considerable break between the Magnesian Limestone and the 

 New Red Sandstone, and this opinion was completely confirmed as 

 I continued my survey northwards through Nottinghamshire into 

 Yorkshire. Unfortunately I did not make a statement regarding 

 this break between the two formations in my Explanation on Sheet 

 71 N.E. Wishing to compress my observations as much as possible 

 to form a pamphlet, the price of which would not be more than six- 

 pence, much that might have been of interest was left out. But in 

 my Explanation on Geological Map Sheet 82 N.E., the country 

 in the neighbourhood of Worksop, I have given my proofs of this 

 great break. I have shown that in the district to the north of 

 Worksop the Permian series consists of at least four divisions. To 

 begin at the top, there are the Upper Marls ; next below the Upper 

 Magnesian Limestone so-called, though it contains little or no Car- 

 bonate of Magnesia ; then the Middle Marls and Sandstones ; and, 

 lastly, the lowest and chief member of the Permian series, the Lower 

 Magnesian Limestone. I state that the Bunter Sandstone overlaps 

 the Up]3er Permian Marls throughout most part of the district, and 

 before the neighbourhood of Worksop is reached the Upper Limestone 

 is also overlapped. From Worksop southward to Nottingham there 

 are only left the Middle Marls and Lower Magnesian Limestone. 

 Between these two places the Middle Marls are frequently over- 

 lapped, and, finally, west of Nottingham, the Lower Magnesian 

 Limestone is itself overlapped, the New Eed Sandstone resting on 

 the Coal-measures. Therefore, in the neighbourhood of Nottingham, 

 instead of there being a perfect conformity between the Magnesian 



