238 LOWER MIOCENE OF BELGIUM. [Ch. XIV. 



B. 3. Marine green sand of Bergh, Neere- ) T T . _ , , _ 



s , m • tti f Lower Limburg beds. — Lower Ton- 



pen, &c, and Tongres, near Eleyn >• . „ -. ■ B - .. 

 e • J I gnan of Dumont. 



fepawen. ; fo 



Upper Eocene. 



C. Calcareous sandy beds of Laeken, near Brussels, with nummulites, &c, of 

 same age as the " Sables Moyens " of the Paris basin and the Barton clay 

 of Hampshire. 



The uppermost of the three subdivisions (B. 1) into which the 

 Lower Miocene or Limburg series is separated in the above table, con- 

 tains at Kleyn Spawen many of the same fossils as the clay, above 

 mentioned, of Rupelmonde and Boom, places sixty miles N.W. of 

 Kleyn Spawen. 



The lower, or Tongrian divisions, B. 2 and B. 3, are much better 

 developed at Kleyn Spawen than B. 1. The first of these, B. 2, con- 

 sists of several alternations of sand and marls, in which a greater or 

 less intermixture of fluviatile and marine shells occurs, implying the 

 occasional entrance of a river neaf the spot, and possibly oscillations 

 in the level of the bottom of the sea. Among the shells are found 

 Cyrena semistriata (fig. 172), Cerithium plicatum, Lam., (fig. 173) 

 Rissoa Ckastelii, Bosq. (fig. 175), and Corbula pisum (fig. 171), four 

 shells all common to the Hempstead or British Lower Miocene beds 

 of the Isle of Wight, to be mentioned in the sequel. With the above, 

 JLucina Thierensii, and other marine forms of the genera Venus, 

 Limopsis, Trochus, &c, are met with. 



In B. 3, or the Lower Tongrian, more than 100 marine shells have 

 been collected, among which the Ostrea ventilabrum is very conspi- 

 cuous. Species common to the underlying Brussels sands, or the 

 Upper Eocene, are numerous, constituting a third of the whole ; but 

 most of these are feebly represented in comparison with the more 

 peculiar and characteristic shells, such as Ostrea ventilabrum Mytilus 

 Nystii, Voluta suturalis, &c. 



Whether this Lower Tongrian should be classed as the lowest 

 member of the Miocene series, or as the uppermost of the Eocene, 

 or, in other words, as the marine equivalent of the freshwater gypsum 

 of Paris, is a question not yet decided. I incline at present to the 

 belief that it is somewhat newer than the Paris gypsum, but certainly 

 near the boundary line which separates the two systems. Its relation 

 to the Upper Eocene deposits of England or the Isle of Wight will be 

 more fully discussed in the sixteenth chapter, p. 281. 



In none of the Belgian Lower Miocene strata could I find any 

 nummulites ; and M. d'Archiac had previously observed that these 

 foraminifera characterized his " Lower Tertiary Series," as contrasted 

 with the Middle, and they therefore served as a good test of age be- 

 tween Eocene and Miocene, at least in Belgium and the North of 

 France.* 



* D'Archiac, Monogr., pp. 7y, 100. 





