504 



J. F. BLAKE OKT TEE UPPER 



Eehinohrissus scutcttus, Holectypus depressus, and Colly rites bieordatus 

 add their testimony to the great similarity which the fauna of this 

 ironstone bears to the lower portions especially of the calcareous 

 series of our Corallian rocks. 



This Ferruginous Oolite is referred by Hebert (21) to the middle 

 Oxfordian on the ground that above it at Vieil-St.-Remy occurs a 

 great thickness, 160 feet, of brown marls with a thoroughly Oxfordian 

 fauna, such as Ammonites arduennensis, Trigonia perlata, Gervillia 

 avicidoides, Ostrea dilatata, &c. The occurrence of any such marls is 

 denied by Buvigner (22) who states that the Oolite seen below must 

 be out of place. Certainly no such thickness of marl was observed 

 where the beds were examined. About 40 feet of marls are seen at 

 the base of the valley near Vieil-St.-Remy and in the railway-cut- 

 ting near Neuvizy ; but these, from their position, are more probably 

 below the Ferruginous Oolite, which is seen too near to the Corallian 

 limestones on the road between Vieil-St.-Remy and Novion to allow 

 of any intervening clay of more than a few feet thickness. It is 

 probable therefore that the Grit and Ferruginous Oolite are hidden 

 on the road to Wagnon in the 160 feet, the base of which contains the 

 above fossils, while over it come the marly limestones recorded to 

 contain Gidaris florigemma and Peeten articulatus. In many other 

 places further south also some representative of the Coral Rag is 

 found immediately overlying the Ferruginous Oolite ; so that its posi- 

 tion is, in reality, perfectly fixed. 



The constancy of this bed in spite of its thinness is in striking 

 contrast with the variability of the succeeding series on the horizon 

 of the Trigonia-beds of Pickering or of the earliest limestones of the 

 Corallian series, which are said by Buvignier to have nothing constant 

 but their inconstancy. 



In the neighbourhood of Vieil-St.-Remy and Neuvizy the lowest 

 beds referred to the Coral Rag are not well seen, though Hebert (21) 

 describes about 4 feet to 5 feet of coral material with Cidar is florigemma 

 on the road to Wagnon. Nowhere here, however, is there any great 

 thickness of such growth ; and what there is is succeeded immediately 

 by the white limestone which is seen so well at the quarries of No- 

 vion. This limestone has been much acted on by chemical agents, 

 many of the fossils being silicified and others represented only by 

 casts. Among the latter the corals are of the greatest importance ; 

 the majority are not Thamnastraean but Calamophyllian and Clado- 

 phyllian. MM. Sauvage and Buvignier simply place the whole of 

 these limestones, amounting, according to their estimate, to 250 feet, as 

 Coral Rag, without further subdivision, and supply a rather defective 

 list of fossils. At Novion a magnificent section, 100 feet in thickness, 

 is seen, the CalamopliyTHai in places almost forming a reef at the 

 base ; then follow great false-bedded masses of fine white limestone, 

 and towards the top huge crystalline nodules of Thamnastrcece. 

 Lithologically therefore this might well pass as a Coral Rag ; and it 

 represents in this area all that would naturally be called Corallian. 

 When, however, we examine it more closely, we note in the first 

 place that this is scarcely a Thamnastraean reef, such as is usual in our 



