292 Messrs Miirchison and Lyell oil the Tertiary 



coal is bituminous, highly compact, and shining ; does not soil 

 the fingers, and serves for all the purposes of domestic use, as 

 well as for those of the large iron factories of the arsenal of 

 Toulon. 



The various carboniferous strata are characterized by diffe- 

 rent groups of shells; and the workmen have availed themselves 

 of these organic remains to distinguish the order of the beds. 

 One stratum, in pai'ticular, is well marked by the presence of a 

 large unio ; others by planorbis (P. cornu ?), and a new species 

 of melania, as also by two species of cyclas, hitherto undescribed, 

 all of which have been named, and are now figured by Mr 

 James Sowerby, as Melania scalaris, Cyclas concinna, and 

 C. cuneata. The shells among which the cyclades are most 

 abvmdant, form numerous thin laminae, dividing the black coal 

 by white lines parallel to the planes of stratification. 



The charcoal between some of the laminae of coal is fibrous, 

 and in some cases made up of a fasciculus of minute dull black 

 tubes, of a plant resembling Endogenites baccillare of Lobsann, 

 in the Lower Rhine^ and of Horgen, near Zurich, and thus dif- 

 fers much in appearance from the satin-like lustre of the char- 

 coal of old coal ; whilst it is a most curious and novel fact, that 

 we observed casts of the seed-vessels of charas even in the coal 

 itself. 



In conclusion, we may remark that the general physiognomy 

 of these lower members of the great tertiary deposite occurring 

 between Aix and Fuveau, differs remarkably not only from 

 the character of the beds of white gypseous marls, sandstone, 

 and limestone on the north of Aix, but from any other fresh 

 water formation examined by us in central France. The great 

 thickness of the regular beds of blue limestone and shale, the 

 quality and appearance of the coal, the large developement of 

 the compact grey, brown, and black argillaceous limestones and 

 sandstones, together with the red marls and gypsum, gives to 

 the whole series the aspect of the most ancient of our secondary 

 rocks ; and it is only by the occurrence of fluviatile and lacus- 

 trine shells, and the ^eed-vessels of charae, that the geologist is 

 undeceived, and recognizes, from the unequivocal specific cha- 

 that the coal measures extend over an area of 10,000 French myriametres, 

 from Trets, on the west, to the Etang de Berre, on the east. 



