1852.] 



LYELL — BELGIAN TERTIARY FORMATIONS. 



325 



iron. In the sands above this conglomerate are many geodes and 

 large hollow pipe-like concretions of hydrate of iron. Below are 

 ochreous, yellow, ferruginous sands (e), which M. Meugy, adopting 

 the opinion of M. Dumont, has called "Tongrian" in his map of 

 French Flanders, thereby implying that they belong to the Limburg 

 or Upper Eocene series described above, § 6. They are about 50 feet 

 thick in Mont Noir (where they are far better exposed to view than 

 at e, fig. 4, in the Hill of Cassel), and at the depth of 30 feet from 

 the top contain an irregular and discontinuous bed of rolled chalk- 

 flints, some of them large, or from 4 to 8 inches in diameter. Fer- 

 ruginous sands are seen above and below the gravel. In some of 

 those immediately below it are casts of shells, to which my attention 

 was first called by M. Meugy, and of which many were collected for 

 me by M. Curtel, a French engineer, with whom I explored the hill. 



Fossil Shells of the Ferruginous Sands next below the JDiest Sands 

 in Mont Noir near Cassel. 



1. Corbula gallica, LamTc, 



2. , another species. 



3. Thracia? 



4. Sanguinolaria HoUowaysii, Sow. 



5. Tellina. 



6. Lucina divaricata ?, LamTc. 



7. Cytherea suberycinoides, Besh. 



8. , another species. 



9. Cardium porulosum, Brander. 



10. semigranulatum, Sow. 



11- turgidura, Brander, 



12. Pecten reconditus, Brander, sp. 



13. Ostrea inflata, Besh. 



14. Dentalium strangulatum, Besh, 



Bitrupa ? 



15. Natica sigaretina, LamJc. 



16. ■ patula, Besh. 



1 7. ambulacrum, Sow. sp. 



18. Turritella imbricataria, Lamk, 



19. Buccinum junceum, Sow. 



20. Voluta. 



21. Conus antediluvianus ?, Z«m^. 



The Sanguinolaria HoUowaysii is a well-known English species, 

 occurring at Bracklesham, and the whole list is such as we might 

 meet with in the Upper Bagshot Sands, to which these beds bear a 

 considerable mineralogical resemblance. The absence of all fossils 

 peculiar to the Limburg series, both here and in the Cassel chain of 

 hills generally, makes me question the propriety of referring these 

 sands to the " Tongrian" beds of Dumont. The casts of Ostrea in- 

 fiat a are numerous, and this fossil abounds at Cassel, as we shall 

 presently see, in beds (lower in the series) which contain Nummulites 

 variolarius in profusion. At Mont Noir the section below the ferru- 

 ginous sands is imperfectly seen or barren of fossils, but in the 

 neighbouring hill of Boeschepe, to the westward, the same yellow 

 irony sands as those of Mont Noir recur, with some white and green 

 sands associated, beneath which are grey, bluish, and greenish sands, 

 20 feet thick, with thin layers of clay, and a fossiliferous glauconite, 

 which I shall now describe. 



The glauconite alluded to is only 6 inches thick. It contains 

 coarse grains of blackish green earth, and is without calcareous matter. 

 It was laid open in a cutting, at the time of my visit, for a road 

 which runs south and north from the village of Berthen to Boeschepe 

 (see Map, PL XVII. fig. 1). Casts of the following fossil shells oc- 

 curred in the glauconite, only a few feet below the level of the water- 

 shed of the ridge, and on its northern side. 



