JURASSIC OF THE PARIS BASIN. 



529 



line therefore can be drawn, it is above this that the Astartian zone 

 should commence. Next comes (4) a mass of abont 30 feet of solid 

 huht- coloured sublithographic stone, with two bands of remarkable 

 character, made up of rolled fragments recemented, with Naticce, 

 Pecten striatus, Oeromya wabrensis, and abundance of Terebratula 

 Leymerii. It is just such a band as this that Prof. Hebert (31) 

 elsewhere thought a good line of separation, showing the distinctness 

 of Astartian and Corallian beds ; but, as it is obvious that they 

 cannot both be such, they both lose their importance, and prove that 

 there were frequent changes in the deposits about this period. This 

 same feature is indicated by subsequent deposits in this section, in 

 which are many rubble-beds alternating with lithographic lime- 

 stones and occasional oolites. Such beds have a thickness of about 

 60 feet, and contain Plioladomya Protei, P. rostralis, Thracia tenera, 

 Pecten Tombecki, Terebratula Leymerii, Rhynchonella ? matro- 

 nensis, Cidaris Smithii, &c. This is followed by the Yirgulian 

 marls, full of Exogyra virgula and Plioladomya rostralis, for 

 16 feet, exposed in the roadside, but extending far up the hill, and 

 finally surmounted by lithographic limestone, with Terebratula 

 subsella. On continuing the route to the Eiceys the descent of the 

 hill shows a second section corresponding closely with the first, until 

 the chalky limestones (2) are reached ; but beneath these, instead 

 of the shelly limestones with only traces of Diceras, is a large deve- 

 lopment of true rubbly Diceras oolite, of which 15 feet in sheer 

 height are seen in one spot, although there may be much more of it. 

 These beds form the cappings of the hills, and assist in producing 

 the magnificent escarpments which overlook both sides of the river. 

 Wherever these Diceras-beds occur they never require to be looked 

 for ; and where they do not form a marked feature it is pretty certain 

 they are absent. The principal fossils noted were Nerinoea umbili- 

 cata ?, Diceras arietina, Nerita Royeri ?, Trigonia Etalloni, and Rhyn- 

 chonella matronensis. . Beneath these, on the west side of Bicey Bas, 

 is worked a mass of 6 feet of a compact oolite, with few fossils in a 

 crystalline state. Underlying this, again, is a considerable quantity 

 of white chalky limestone, tending to be flaggy on weathering, and 

 occasionally false-bedded. Of this there may be 60 or 70 feet, the 

 principal fossils being Plioladomya striatula, Avicula Gesneri, and 

 Rhynchonella pinguis. In downward succession we reach, at Le 

 Yannage, a quantity of shelly limestone, with abundance of corals, 

 in which Pecten vimineus, RJiynchonella corallina, &c. abound, but 

 in which no Cidaris florigemma could be found. On crossing the 

 boundary into the department of the Cote d'Or, at a very slightly 

 lower level, there are numerous quarries in a calcareous grit, whose 

 horizon is accurately fixed by the occurrence of Trigonia spinifera. 

 In the last-named department there is a very considerable develop- 

 ment of the lower coral-beds, with Pecten vimineus and Rhynchonella 

 corallina, followed in regular succession by the Oxford grit and marls. 



This traverse has been given in greater detail because it appears 

 to be a very important one, not hitherto noticed or described, and 

 serves for a term of comparison between the series of the Aube 



Q. J. G. S. No. 148. 2 n 



