Vol. 52.] A DELIMITATION- OF THE CENOMANIAN". 



7. A Delimitation- of the Cenomanian : — being a Comparison of the 

 Corresponding Beds in So ct a- western England and Western 

 France. By A. J. Jukes-Browne, Esq., B.A., F.G.S., and 

 William Hill, Esq., F.G.S. (Read January 8th, 1896.) 



[Plate V.] 



Contents. 



Page 



I. Historical Introduction 99 



II. A brief Description of some Sections on the South Coast of 



England 103 



III. A Study of the Cliffs between Cape La Heve and Brunval ... 115 

 IV. A Correlation of the Cenomanian Deposits in the Calvados, 



Orne, and Sarthe 126 



V. The Minute Structure of some of the Beds in England and 



France 136 



VI. Critical Bemarks on some of the Fossils 142 



VII. Lists of Cenomanian Fossils found in Devon and. in 



Normandy 158 



VIII. Summary and Conclusions 170 



Diagrams facing 113, 114, 118, 124, 172 



I. Historical Introduction. 



The object of this paper is to compare the beds which form the 

 lower part of the Upper Cretaceous series in those parts of Western 

 France and Western England which are nearest to one another. 

 In England these beds are known by the names of Gault, Upper 

 Greensand, and Lower Chalk ; in France they are classed under 

 d'Orbigny's ' Albien' and ' Cenomanien ' stages. It is well known 

 that in both countries the deposits referable to these groups change 

 their lithological character so greatly, in passing towards the west 

 and south-west, that different observers have formed different 

 opinions in their attempts to correlate one area with another. 

 Further, no geologist has yet endeavoured to make a careful con>- 

 parison of the French and English types ; but it is only by such a 

 comparison that the true slratigraphical position of d'Orbigny's 

 Cenomanien stage can be determined, and that the limits of this 

 stage in areas outside the typical Cenomanian district can be fixed. 

 The name 'Cenomanien' was introduced by d'Orbigny in 1847 

 to designate the lower part of the series which he had previously 

 called ' Turonien,' when he found that this lower portion contained 

 a fauna essentially distinct from that of the upper part. 1 He 

 then proposed to retain the name ' Turonien ' for the upper part, 

 and to adopt the name ' Cenomanien ' for the lower part, taking the 

 name from Le Mans, in the Sarthe, the Cenomanum of the Romans,and 



1 ' Paleont. Francaiae : Terr. Cretace,' vol. iv. p. 270. See also his ' Cours 

 elementaire de Paleontologie et de Greologie stratigraphiques,' 1852, vol. ii. 

 p. 631. 



Q. J. G. S. No. 206. 1 



