FresJi-water Formations of Aix, in Provence. 291 



on the northern side of the valley ; and we now proceed to those 

 on the south flank. Here, to the south of the river Are, we 

 find a country extending for many miles in the direction of 

 Toulon (intersected by a series of valleys having the same gene- 

 ral direction, viz. from east to west, as the principal valley of 

 Aix), composed of a great succession of fresh water strata, ge- 

 nerally inclined to the north. This district is divided by de- 

 pressions parallel to the pi'incipal valley of Aix, into several 

 broad elevated ridges, the northernmost of which, containing 

 the superior beds, exposes a considerable thickness of red marl, 

 with gypsum of a fibrous silky texture, and therefore differing 

 in character from the gypsum to the north of Aix. Interstra- 

 tified with the above are beds of a very compact limestone, in 

 which we found Planorbis rotundatus, and casts of a reversed 

 limnea. In the succeeding ridges, solid strata of brown earthy 

 limestone occur, with micaceous and calcareous sandstones, and 

 party-coloured shales. In this limestone are numerous frag- 

 ments of limneae, associated with gyrogonites, the latter being 

 very abundant, but as we could only procure casts of the in- 

 terior of the seed-vessel, we cannot determine the species. It is 

 of smaller size than any of those occurring in the Paris basin, 

 but of the same spherical shape. Its magnitude does not ex- 

 ceed that of the seed-vessel of Chara fiispida, — the recent species 

 found fossil in the marl lochs in Forfarshire. 



Still farther to the south, inferior beds of grey fresh >vater 

 limestone, .sandstone, and shale, crop out ; and at length, to the 

 south of Fuveau, is seen a great series of beds of blue lime- 

 stone, and shale, with workable coal. The collieries visited by 

 us are situated about two miles to the south of Fuveau, where 

 the strata have been pierced to the depth of 500 feet and up- 

 wards. The dip is uniformly to the north, but the degree of 

 inclination varies in different pits. The beds consist of blue ar- 

 gillaceous limestone, from three to five feet thick, of very regular 

 stratification, and separated, for the most part, by thin way- 

 boards of shale, about six inches thick. The principal coal 

 seam is not more than from nine inches to a foot thick, and the 

 united thickness of all the scams rarely exceeds five feet *. The 



• M. Tliolouzan, in the " Statistiijues des bouches de Khone," states 



