Environs of Lons le Saunier, 



ing at any point ; but it is very remarkable on acconnt of its 

 constant inferior position to the gypsum masses, to which it 

 may serve as a guide, and by its great length ; it has been 

 recognized as far as the department of the Doubs. 



I shall not further extend my observations on the gryphite 

 limestone formation, in order to arrive more speedily to the 

 following 



OOLITE LIMESTONE FORMATION. 



Examination of the beds composing it. 



The marls of this formation differ from the preceding by 

 their constant grey or slate blue colour, by their much more 

 slaty texture, often by their bituminous nature, and by the 

 fossil shells they contain. 



The lowest are compact, fragile, and of a slight grey tint ; 

 they contain a very great number of small ammonites, beleni- 

 ilites, entrochi, some small pectens, and terebratula? ; the 

 shells are found changed inlo pyrites. These first marls con- 

 tain nests of cubic pyrites, and oxide of iron, arising from 

 the decomposition of the sulphur. 



Higher up, fewer ammonites are found; the marl becomes 

 earthy, and contains thick beds of marly limestone, in which 

 small bacculites truncated in the manner of entrochi are 

 seen. 



After a great number of beds with few shells, one is met 

 with of prodigious richness as to species ; belemnites, pec- 

 tens, and anomiae, grouped in families, form alternatiiio^ 

 strata, in which the cementing rock is scarcely discernable ; 

 among other less abundant shells that it contains, I may 

 notice ammonites, donaces, nautili, mytili, baculites, en- 

 trochi, and cardiae. 



The grouped shells are generally small ; but isolated 

 belemnites 16 centimetres [six inches] long are found, and 

 ribbed pectens of the size of the hand, that are easily de- 

 tached from the rock; it is remarkable that the small bivalve, 



