162 



from London to Dover, precisely resemble those in the same situa- 

 tion, on the line from Calais through St. Omer, Cassel, and Lille, 

 &c: the prominent hill of Cassel, however, is not topped with clay, 

 but seems to consist entirely of sand, including very numerous fossils, 

 contained principally in loose concretional beds of stone. These 

 fossils, many of which are the same with those of similar sands near 

 Brussels, agree, in general, with those of the London- clay ; and 

 thence it would appear, that the separation of that stratum from the 

 sands immediately incumbent on the chalk is not well founded. 

 Beds of the sands here referred to occur, in the same geological 

 place, in Kent; near St. Omer; at Cassel; at Mount-Panisel, and 

 Ciply, south of Mons ; at Brussels; between Charleroi and Fleurus; 

 and at Kleyn-Spauwen, between Tongres and Maestricht. 



2. Maestricht stratum. — Between the deposition of the sands 

 last mentioned and of the chalk, a considerable interval must have 

 elapsed ; during which various beds may have been deposited, 

 of which no trace, or but obscure remains exist, at present, in En- 

 gland. The well-known stratum of St. Peter's-Mount near Maes- 

 tricht is one of these : it is throughout superior to the white chalk, 

 into which it passes gradually below, but the top bears marks of 

 devastation, and there is no passage from it to the sands above. The 

 siliceous masses which it includes are much more rare than those of 

 the chalk, of greater bulk, and not composed of black flint, but of a 

 stone approaching to chert, and, in some cases, to calcedony : — and 

 of about fifty species of its fossils in the author's collection, about 

 forty are not found in Mr. Mantell's catalogue of the chalk fossils 

 of Sussex*. The author therefore, with Mr. Honyf, and Mr. 

 ConybeareJ, regards this bed as differing from, though intimately 

 connected with the chalk. 



A very fine section of the Maestricht bed is visible on the sides 

 of the valleys of the Meuse and of the Jaar ; and in the heights op- 

 posite to Vise the bed, gradually rising from Maestricht, disap- 

 pears, and is succeeded by white chalk with flints. The section 

 of this stratum, and all the accompanying circumstances, at Ciply, 

 south of Mons, accord remarkably with those of Maestricht ; and 

 from M. Desnoyer's statements, a bed of the same description seems 

 to exist also in the Cotentin. 



3. Chalk. — The thickness of this stratum in the Netherlands is 

 much less than on the coasts of the Channel ; especially of the part 

 containing flints, which is succeeded, in descending, by chalk with- 

 out flints, passing into marl, and thence into fire-stone and green- 

 sand. The white chalk is well seen at Wonck and Heur le Romain 

 opposite to Vise; and, on the north of Aix-la-Chapelle, a remarkable 

 group, which the author refers to the lower part of the chalk, con- 

 sists of hard beds of grey and cream-coloured limestone, alternating 

 with calcareous sand. This stratum, which abounds in fossils, many 

 of them belonging to the lower chalk of England, has been found 

 at a considerable depth at Cawenberg on the north-west of Maes- 



* Geol. Trans. 2d Series, III. 201. 



t Geol. Trans. II, 310. % Outlines, p. 63. 



