330 Dr. FiTTON on the Strata below the Chalk. 



Cardium, Venus, Trigonia, Sanguinolaria. The pisiform ore of the Haute Saone appears from the 

 statements of M. Thirria to be above the Portland strata ; but its relations to the superior forma- 

 tions are less distinct. It contains Ammonites, Hamites, Nerinea, Cirrus, Terebratula, and 

 Pentacrinites, with teeth of fishes and of Saurians : and it is observable that the uppermost stratum 

 in the group supposed by M. Thirria to represent the Portland stone, is "a compact conchoidal 

 " limestone, a little tubercular, which contains a species of Paludina? near to Vivipara fluviorum 

 " of Sowerby ; " — a description which might very well be applied to some of our Purbeck 

 strata. 



M. Walchner has ascertained that the pisiform and reniform iron ores of Candern, belong to 

 two distinct formations, of very different date. The lower rests upon beds of "Jura limestone ", 

 which he refers to the Coral-rag or Portland-stone, and which are decidedly below the molasse of 

 Switzerland. The second and more recent pisolitic deposit occupies eroded cavities on the sur- 

 face of several different formations; it consists of transported matter containing fossil bones, and 

 is not covered by any solid strata. M. Merian is cited by M. Walchner in support of this view of 

 the relations of these deposits ; but in the description given by the former, of the strata which im- 

 mediately cover the pisiform ore of Aarau, there are features very like those of our Wealden 

 itself: for they are mentioned as consisting of " grit and bituminous schist passing into lignite, and 

 " containing a great number of petrifactions, among which, though commonly indistinct, are a 

 " Planorbis, and other freshwater shells." 



The doubt which obviously presents itself with respect to the evidence above mentioned, is, 

 whether a formation thus contiguous to the green-sands, and so very nearly coeval with them, may 

 not really be a part of that formation itself; the presence of some fossils distinct from ours, not 

 being sufficient to prohibit this identification. But the peculiar character and abundance of the 

 iron ore, are important circumstances of difference. 



The evidence respecting Bornholm occurs in a paper read before the Geological Society by 

 Dr. Beck of Copenhagen*, who states that the beds below the cretaceous group in that island, 

 exhibit many of the characters of a coal formation, containing coal and numerous impressions of 

 ferns, among which are several of the genus Pecopteris ; and with these was found the seed 

 vessel of a Restiacea, considered by Dr. Beck as identical with one from the Hastings-sand at 

 Heathfield in Sussex, which he himself had seen in Mr. Mantell's collection. The existence 

 in the vicinity of Hoer, of fossil plants analogous to those of the Wealden, but probably be- 

 longing to the oolitic series, had been previously pointed out by Mr. Adolphe Brongniartf : but 

 from what has been very recently mentioned to me by Professor Nilsson of Lund, after he 

 had examined some of our best collections of the Wealden fossils, it is probable that a deposit 

 contemporaneous with that formation may be found at Helsingburg in Scania, between the chalk 

 and green-sands which occur near the coast of the Baltic, and the Lias, known to exist on the 

 north-west of that place 



The observations of M. Boblaye in the north];, of M. Desnoyers § in the north-west, and of 

 M.DufresnoylJ; in the south-west of France ; with those of M. Elie de Beaumont, on the boundary 

 of the Paris and London Basins^ ; of Mr. De la Beche **, M. de Caumontf f , M. Desnoyers]:], 



* "Proceedings" (1835-6) vol. ii. p. 217. t Annales des Sciences Naturelles, 1825. 



+ Ibid., 1820, t. xvii. p. 35. § Ibid., 1825, t. iv.p. 353. || Ibid., 1829, t. xvii. p. 192 



<l[ Ibid., 1829, t. xvii. p. 354. ** Geol. Trans. 2nd Series, vol. i. p. 13. 



+T Mem. de la Sac. Linn, du Calvados, t. i. 1824, p. 49 et 67 ; t. ii. 1825. p. 447, &c, 

 ;i Mem. de la Soc, d'Hist. Nat, de Paris, t. ii. 1825. 



