310 M. Levallois on the 



Beneath about 2 metres [about 6 feet 7 in.] of vegetable 

 soil : 



1 metre [about 3 feet 3 inches] of a compact and hard 

 stone, though decomposing in the air. This stone 

 is white with a slight greenish tint : it effervesces 

 but very slowly with nitric acid, leaving a siliceous 

 residuum. It is a marly siliciferous limestone : 

 the bed is divided into thin strata. 

 1 ditto slaty marls, red in the upper part, green in the 



lower. 

 1 ditto of a marly siliceous limestone, analogous to that 

 of which we have just spoken ; it is only more 

 compact, with a more conchoidal fracture. It has 

 sometimes a reddish tint : some pieces are in- 

 crusted with calcareous spar. 

 0,15 ditto of red and green marls. 

 1,50 ditto of compact reddish gypsum, slightly mixed 



with marl. 

 0,50 ditto of gypsum in small pieces as if squared, dis- 

 posed in the plane of the beds and separated by 

 marls. 

 1,50 ditto of gypsum slightly mixed with maris. 

 1,80 ditto of poor gypsum in nodules mixed with marl. 

 0,50 ditto of red marls mixed with a little gypsum, and 

 principally containing fibrous gypsum in veins 

 parallel to the beds. 

 3 ditto nearly forming the white gypsum bed named 

 the galerie. 

 2,33 ditto forming the bed of gypsum named the fond. 

 They no longer work beneath this bed, but marls mixed 

 with gypsum are still found. Still further down sand is met 

 with. 



In tliese three quarries, the beds are nearly in parallel 

 stratification. They succeed each other precisely in the 

 same order and with the same thickness. They are in gene- 

 ral slightly inclined, and appear undulated ; at least we are 

 led to believe so as they are slightly arched in the three 

 quarries. The dip is most generally towards the west. 



