JURASSIC OF THE PARIS BASES. 



519 



stratified form at a distance of 500 yards. A second cross fault 

 cuts off Cultra from the cliff of Bettaincourt. where the great 

 Diceras-beds occupy the ground down to the stream. The relation, 

 therefore, of the two parts of the Corallian rocks is not here so clear 

 as could be wished ; but some portion of the Diceras-beds are seen 

 to be lying on the top of the rubbly limestones further back at 

 Roche-sur-Rognon ; and at Eeynel, about 3 miles to the east, Tom- 

 beck (55) describes an admirable section, having at the base Qx- 

 fordian marls with 0. dilatata, then grey marls with Cidaris flori- 

 gemma and Hemicidaris crenidaris, next a mass of coral limestone 

 with corals in situ, gradually becoming oolitic and then pisolitic as at 

 Bettaincourt, the whole being 300 feet in thickness. Notwithstand- 

 ing this section, however, he thinks (65) that the one form changes 

 into the other. 



The Diceras-beds at Bettaincourt, first seen here in a journey 

 westwards in their full development, are marvellous deposits. They 

 consist of rolled fragments of all sizes, coated with calcareous cement, 

 and which in one sense may therefore be called oolitic grains ; but they 

 have been subjected to a very different variety of the process which 

 produced the concentric coats of the latter. In oolites the process 

 is tranquil, in these tumultuous and rapid, the whole presenting the 

 appearance of a substratified heap of rubbish from a neighbouring 

 centre of life, borne along by the ancient currents which swept 

 through the straits of Dijon. Such beds might be supposed to re- 

 place, with almost any rapidity, the coral-growths from which they 

 are derived, or to die out entirely. There are, however, great 

 varieties in the Diceras-beds themselves — pisolites, large -grained 

 oolites, suboolitic, and thin-splitting limestone alternating ; and 

 various groups of fossils are found in the various parts ; but yet 

 the whole is indivisible. With many Dicerata occur Cidaris flori- 

 gemma, Cardium corallinum, and many rolled sponges. The other 

 fossils noted were Nerincea sequana and other species, Littorina 

 muricata, Isocardia striata, Corbis gigantea, Lima Iceviuscula, L. 

 pectiniformis, Trichites sp., Ostrea pidligera, and Terebratula mal- 

 tonensis. "What the real thickness of these beds may be it is im- 

 possible to say ; their stratification is so irregular, and their change 

 of character in a lateral direction so marked, that all estimates are 

 worthless. Perhaps 300 feet may be seen in the Bettaincourt hill-side if 

 there is no real dip ; but even more may be introduced in the five miles 

 over which the deposit spreads. It is, of course, easy (50) to pick 

 out one of the oolitic portions, and call it the " oolithe de Saucourt," 

 and another above this, and call it the " oolithe de La Mothe ; " but 

 the actual oolites which occur at those places are not therebv proved 

 to be superimposed, unless they are proved identical with these 

 beds, which has not been, and cannot be done. The whole forms 

 one great mass (here at its maximum of development), representing 

 on the one hand the Novion and Vadonville limestones, and on the 

 other the whole mass of the Diceras-beds further to the west. The 

 upper portion is certainly more compact than the lower. On reach- 

 ing Saucourt the peculiar character of the Diceras-beds is lost ; and 



