zW M. Brongniart on the fosnl 



nesss and extent that subterranean workings can never offer. 



This natural section of the formation is not only interest- 

 ing from the circumstance of the fossil vegetables that form 

 the principal object of this notice ; but also for the presence 

 of compact carbonate of iron ore, which so constantly ac- 

 companies the coal, and which will soon become in France, 

 as it has long since been in England, the object of great re- 

 search, and a species of industry new to us. 



By confining the examination in the Treuil mine to the 

 portion represented in the view (pi. 7), that is joined t© 

 this notice, there is remarked passing from the bottom to the 

 top, i. e. from the lowest terrace to the surface of the ground ; 



1st. A bed of coally spangled clay-slate (*), which is 

 soon followed by a bed of coal (H), about 15 decimetres 

 [5 feet] thick. 



2dly. A second bed of the same slate (*), but thicker, 

 and containing in its lower strata and very near the coal, 

 four beds of compact carbonate of iron ore (F), in flattened 

 nodules, cleanly separated from each other, more or less vo- 

 luminous, or in large plates swollen in the middle, accom- 

 panied, covered, and even penetrated by vegetable remains ; 



3dly. And at the second terrace above this schistose bed, 

 another bed of coal (H), which is from 46 to 50 centimetres 

 Fabout 20 inches] thick, and which is covered by a bed 

 composed of schistose clay (*), resembling the inferior one, 

 from four to five thin seams of coal, and towards its upper 

 part of three or four thinner seams, and closer together, of 

 carbonate of iron (F), in every respect resembling that of 

 the first terrace. 



The schists and iron ore are accompanied by numerous 

 vegetable impressions, which cover their surfaces and follow 

 all their contours ; 



4thly. Lastly, and here terminating the coal measures, 

 a bed 3 or 4 metres [about 9 f. 10 in. to 13 f. 1 in.] thick oc- 

 curs, of a micacous sandstone, sometimes simply split in va- 

 rious directions, sometimes very clearly stratified, and even 

 passing in the mass into the slaty structure. 



In this bed, and over a great extent, numerous stems oc- 



