JTRASSIC OP THE PARIS BASIX. 



515 



stone when thickened out in the neighbourhood ; and, finally, coarse- 

 grained thin -splitting oolites occupy the summit of the hill. There 

 is thus no proof of our having here reached the top of the limestones ; 

 and yet these are at least 300 feet above the Oxford Grit, all of 

 which must be placed in the Coral Rag and Supracoralline beds. 

 The continuation of the route, however, reads us a very instructive 

 lesson. On consulting Buvignier's detailed map it will be seen that 

 behind this hill there is a long tongue of the lower rocks crossing 

 the road in the valley. Little is to be seen on the descent of the 

 hill ; but on the next rise at Vouthon Bas, the nodular Oxford Grit 

 is seen in the village, and above this successively a shelly limestone 

 full of Cidaris florigemma, massive oolitic rocks, thin-bedded oolitic 

 rocks, and then the lithographic limestone — in a word the same 

 succession as before, but in this instance crowded into a space which 

 certainly cannot exceed 50 feet. So great a change in thickness in a 

 distance of less than 3 miles gives an idea of the very local and 

 fragmentary character of the Corallian rocks. 



The greater part of the distance to Gondrecourt, about 5 miles, 

 is occupied by compact, almost lithographic limestones, with no 

 fossils visible. These appear to be placed by Buvignier, from the 

 colouring of his map, as Astartian. They nevertheless occupy the 

 position of the great masses to the north of Verdun, and perhaps 

 also east of St. Mihiel, which are coloured Corallian ; but in the 

 absence of fossils it is difficult to say to which they should be joined. 

 In this traverse, as in the others, but little sign is seen of the piso- 

 litic Diceras-beds ; only some coarse-grained oolites are seen. Hence 

 the peculiar character so well seen further west is here only occa- 

 sional, or occupies too small a space to be easily discovered. 



Near the entrance to Gondrecourt these lithographic limestones 

 are succeeded by and intermixed with rubbly beds with many 

 fossils. A thickness of about 40 feet is seen, towards the top of 

 which Terebratula subsella is abundant. Similar stone is continued 

 for nearly a mile on the other side of Gondrecourt, and gives a very 

 good idea of the Astartian beds in this district. The fossils here 

 noted were Terebratula sp. (perhaps the young of T. subsella), 

 Pterocera Thirrice, Thracia lata,PholadomyaProtei, Isocardia obovata, 

 Ceromya eoccentrica, Pleuromya rugosa, Mytilus opisoides ?, and 

 Nautilus infiatus. Exogyra virgula is not seen in these beds, which 

 are almost as argillaceous as the overlying series, especially if we 

 include in them all that lies below the first undoubtedly Yirgu- 

 lian bed ; but no pisolitic beds are seen along the road. The base 

 of the Yirgulian occurs at Houdelaincourt, about 3 miles north of 

 Gondrecourt, where a mass of chalky limestones forms a bank 40 feet 

 in height, the upper part of which yields all the fauca of Mxeville, e. g. 

 Ammonites longispinus, Pholadomya multicostata, P. Protein, Astarte 

 supraeorallina, Pinna granidata, and Pecten suprajurensis. Above this 

 come the marls full of Exogyra virgida, then more chalky lime- 

 stones with Pleuromya Voltzii, and finally more marls and marly 

 limestones such as are seen in a cutting further on. This cutting, 

 made for the Marne-and-Ehine canal at Demanges, has been de- 



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