Environs of Lons le Saunier. 129 



the nature of the ground in different localities, in order that 

 the facts I advance may be easily verified; I terminate this 

 memoir by noticing some errors until now adopted respect- 

 ing the composition of the Jura chain. The word formation 

 having received diiFerent significations, I conceive it neces- 

 sary to state that I apply this denomination to all systems 

 of mineral masses, whatever their nature or extent may 

 be, the respective disposition of which proves that they have 

 been formed by an uninterrupted succession of the same 

 causes. 



Numerous observations, which many years residence at 

 Lons le Saunier have allowed me often to verify, have in- 

 duced me to admit two distinct formations. 



The first comprises a very considerable thickness of various- 

 ly coloured marls, which contains many masses of gypsum 

 separated by beds of marl ; the whole of these mineral 

 masses is stratified, and covered by a second mass resting 

 regularly on the first, and composed of uninterrupted beds 

 of gryphite limestone.* 



The second formation comprises a great height of shelly 

 marls constantly of a slate blue colour passing into ash grey, 

 disposed in parallel beds, which contain some subordinate 

 beds of a shelly argillaceous limestone, often bituminous like 

 the marl near them ;t these marls are covered by an 

 enormous mass of limestone generally oolitic, very often 

 passing by insensible degrees into granular and into compact 

 limestone ; it is disposed in strata parallel to each other, and 

 conformable to the marl beds in which it rests. The lime- 

 stone is ferruginous, siliceous, argillaceous, and with or 

 without nodules of flint ; occasionally it contains fossil orga- 

 nised bodies. J 



♦ The first division of this formation will hereafter be seen to be part 

 of the new red or saliferous sandstone formation, and the second division 

 is the lias of our English series. (Trans.) 



+ These marls are the lias marls. (Trans.) 



J This mass of limestone apparently consists of the lower oolite divi- 

 sion, or the great and inferior oolites. (Trans.) 



I 



