REVIEW. 
899 
up as usual of those little oysters from which it takes its name, and is 
sometimes twenty metres thick. The Great Oolite is a very massive lime- 
stone, the upper part of which has been, rightly or wrongly, considered 
by some Continental geologists as representing our Forest Marble. The 
Dalle Nacree (Nacreous Marble) is a small limestone series enclosing at 
its base subordinate beds of clay. The principal fossils of the Dalle 
Nacree are Ammonites macrocephaliis, Schl. ; Am. sub-hackericB, D'Orb. ; 
PJioladomya huccardium, Ag. ; P. Vezelayi, Laj. ; Lyonsia pereffrina, 
PhilL, sp. ; Lavignon mactroides, D'Orb. ; Gervillia acuta, Sow, ; Ostrea 
acuminata. Sow. ; O. costata, Sow. ; Hhynclionella concinna, Sow., sp. ; 
R. Lieteni, D'Orb. ; Terehratula digona, Sow, In tjie Efage O.rfordien, 
M. Contejean includes the Callovian and Oxfordian Etages of D'Orbigny, 
and consequently in the Montbeliard region he admits in tliat group the 
Fer Sous- O.rfordien (Callovian), the Marnes Oxfordiennes (Oxfordian), 
and tlie Calcaires a Splicerites (Argovian). 
His JEtage Corallien is the Etage Corallien of D'Orbigny, less the Cal- 
caires a Astartes. It begins with the Argilles a Ch allies ; to these suc- 
ceed the Calcaires Coralliens proper, which in the Haut-Jura exceed a 
hundred metres in thickness, ^and it is terminated by the Coralline Oolite 
{Oolitlie Cor alii enne^. The Etage Kimmeridien is made also by M, Conte- 
jean to include the Etages Kimmeridien and Portlandien of D'Orbigny, and 
it is this group which most especially occupies the general surface of the 
Montbeliard arrondissement. The four divisions of this etage are the 
Astartien, Pterocerien, Virgulien, and Js^eriueen, 
Between the Portland dolomite and the lowest xfeoeomian beds there are 
intercalated, in many localities, beds which have exercised the wits of many 
geologists, and have given rise to much controversy. These are the Argil es 
des Villiers, a small freshwater formation, considered b}^ some to belong to 
the Jurassic period, corresponding to the Purbeck beds, and by others as 
representing the Weald Clay ; whilst others attach them to the Cretaceous 
Formation, The author expresses no opinion on this point, but points out 
the occurrence of these clays at Villiers-le-Lac, near Morteau, and as oc- 
curring also generally at the base of the i^s eocomian deposits in the canton 
of Bussey, in very variable thickness, but on the average about 10 metres. 
Their colour is dark grey, almost black. The fossils are rare and badly 
preserved. M, Lory has noted Physa Bristovii, Forbes ( P, Wealdiana, 
Coq ), Planorbis Lorii, Coq., Corhula alaia, Sow., and undetermined spe- 
cies of Paludina, Lymneus, and Cyclas. 
The Cretaceous rocks are represented by Neocomian limestones, sur- 
mounted by bands of limonite-iron — the Valenginian group; or as M. 
Contejean prefers to call them, the Calcaire a Limonite, and the Marnes de 
(V Hautcrive and the Calcaires de Neuchdtel. The Calcaire a Cliama (Ne- 
gonien, D'Orb.) does not exist in the arrondissement, nor are any of the 
Upper Cretaceous beds to be met with. 
The Terrain Siderolithique is another small formation which has occa- 
sioned discussion as to its origin, and the place it ought to occupy in the 
geological series. It consists of clays, sands, and grains of iron, confusedly 
heaped in the fissures and open depressions of all the Jurassic beds. The 
iron is worked in numerous places, and some of the mines are very im- 
portant. 
The Molasse extends from the north-east of Montbeliard over the terri- 
tories of Sochaux, Exincourt, Etupes, Brognard, Dambenois, and AUan- 
joie. Isolated by erosions, it forms low and rounded hills. At Montaineau 
the Molasse begins with strong beds of conglomerates of rounded pebbles 
belonging to the Jurassic beds, and often preserving their fossils. These 
