512 



J. F. BLAKE ON THE UPPER 



Coral Rag can be assigned to either of these forms. Above the Coral 

 Rag, on the road to St. Mihiel, are the more compact, almost litho- 

 graphic limestones with Nerincece as before, occupying a wide expanse 

 of country. So far, therefore, the Verdun form is fairly continued ; 

 but when we examine the exposures seen in other valleys an inter- 

 esting modification is observed. The deeper sections on the right 

 bank of the Meuse show the base of the Coral Rag to be occupied 

 by far more oolitic and regularly-bedded stone than any seen at 

 Apremont; but on the left bank, quite close to St. Mihiel, a recent cut- 

 ting gives a first real indication of something corresponding to our true 

 Coralline Oolite. At the base of this cutting is 8 feet of Ferruginous 

 Oolite crammed with fossils — Ammonites convolutus ?, Pholadomya 

 decemcostata and P. deltoidea, Mytilus pectinatus, Perna quadrata, 

 Pecten articulatus, Ostrea dilatata, Bhynchonella lacunosa, Terebratula 

 bucculenta, Oollyrites bicordatus, Bysaster ovcdis, and others. Next 

 comes more than 6 feet of a rather sandy limestone, not exactly 

 oolitic, but thick-bedded, in which no Cidaris florigemma or 

 Pecten vimineus could be found, but such fossils as Ammonites pli- 

 catilis, Pseudomelania striata, Pholadomya deltoidea, Uolectypus de- 

 pressus, and Stomechinus sp. abound. This mass is equally distin- 

 guishable from the Ferruginous Oolite and from the Coral Rag, and 

 occupies the place, hitherto unrepresented, of those deposits which 

 in England form a basis for the latter. The thickness of this mass 

 is not well seen here, and is comparatively unimportant ; but at 

 Creue, 8 miles N.E. from here, Buvignier has described some " lower 

 white limestones " occupying the same position, 250 feet in thickness ; 

 and the same occur also to the south of Apremont at Liouville, and 

 are therefore more or less alternative with the Rag, the great thick- 

 ness of which may be due to its filling up the hollows between the 

 lenticular masses of the " coralline oolite " below. These limestones 

 contain a fauna very distinct from that of the Coral Rag : urchins are 

 almost absent ; Myacidse abound ; and the whole assemblage is much 

 more like that in the Ferruginous Oolite, A. plieatilis being the most 

 abundant cephalopod. It differs, however, from the fauna of the 

 latter rock in the absence of the characteristic urchins, crinoids, 

 brachiopoda, and belemnites. In Buvignier's list 15 of its fossils 

 are common to the Coral Rag, and 34 to the Ferruginous Oolite ; 

 but the latter is only 18 per cent, of the number found in both, 

 so that by any method of percentages these limestones should be 

 reckoned distinct. 



Above the section already referred to, on the left bank of the 

 Meuse, are about 80 feet of Coral Rag, most massive below, with old 

 Thamnastrcece above, and containing all the usual fossils ; and on the 

 ascent of the hill comes on at once a great thickness of beautiful 

 pure white oolite containing scarcely a fossil, though a Corbis and 

 Diceras were noted ; all this, therefore, only continues what has been 

 seen before. What lies above has not been seen ; but detailed ac- 

 counts of it as exposed in the cuttings between Lerouville and Loxe- 

 ville are given by Hebert (21). At Vadonville is seen at the base 

 a great mass of white limestones, finely oolitic, but in places almost 



