530 



J. F. BLAKE ON THE UPPER 



and Haute-Marne and that of the Yonne. The thicknesses given 

 by Leymerie must be maxima ; but the succession he gives is well 

 made out. It is obvious that he reckons the whole down to the 

 Diceras-beds to belong to his Astartian : the first-named is his " no- 

 dular white limestone," though none of his lists of fossils contain 

 Diceras; and the underlying beds observed in the valley of the. 

 Laignes are his "lower coral limestone " in its three subdivisions of 

 " compact limestone," " levique limestone," and " oolitic shell lime- 

 stone." Now it has been seen that the Diceras-beds occupy the 

 position of the shelly limestone of Clairvaux and Bayel, and hence 

 we ought to find the true Coral Bag below in the Aube valley. 

 Unfortunately nowhere has Cidaris fioric/emma been noted ; but the 

 false-bedded character of the "levique" limestones, and the record 

 by Leymerie of a bed in them, at Gloire Lieu, entirely composed of 

 Crinoids (a feature so characteristic of the Coral Hag of the Meuse), 

 leads to the conviction that it is in these limestones we must look 

 for the representative of the Rag, and that the coral shell-beds of 

 the Cote d'Or must be regarded as " Coralline Oolite," so far as any 

 separation of these can be effected. On the other hand the great 

 development of beds below the Diceras-zone and the coralliferous 

 character of the base leads on to what we shall see in the department 

 of the Yonne, and show, to a certain extent, a repetition of the section 

 in the valley of the Marne. 



5. Department of the Yonne. — The general description of the Upper 

 Jurassic rocks in this department is by Leymerie and Raulin, who 

 divide them as follows (25) : — 



Upper Jurassic. 



1. Portland limestones, 135 feet. 



2. Kiinroeridgian marls and limestones, 330 feet. 



Middle Jurassic. 



1. Astartian limestone, 33 feet. 



2. White coral limestone, 300 feet. 



3. Upper Oxfordian limestone. 



4. Middle Oxfordian limestones or marls, 260 feet. 



5. Lower Oxfordian ironstone, 33 feet. 



Equally important, however, in this case are the subdivisions of 

 M. Cotteau (34, 42), though they are not very definitely formulated. 

 They are as follows : — 



PORTLANDIAN. 



1. Zone of Pinna suprajurensis. 



2. Zone of Ammonites gigas. 



KlMMERIDGIAN. 



Sequanian. 



1. White limestones. 



2. Lithographic limestones. 



CoRALLIAN. 



Diceras-beds. 



Oxfordian. 



1. Zone of Ammonites plicatilis and Cidaris fiorigemma. 



