188 LIMBUEG STRATA IN" BELGIUM. [Ch. XT 



from its immmulitic or central portions to its Upper or Limburg beds 

 was clearly made out. 



LIMBURG STRATA IN BELGIUM. 



{^Rupelian and Tongrian Systems of Bumont) 



The best type wbicli we as yet possess of the Upper Eocene, as defined 

 in the foi'egoing observations, consists of the beds formerly known to col- 

 lectors as those of Kleyn Spawen. These can be best studied in the 

 environs of the village so named, which is situated about seven miles 

 west of Maestri cht, and in the old province of Limburg in Belgium. In 

 that region, about 200 species of testacea, marine and freshwater, have 

 been obtained, with many foraminifera and remains of fish. 



The following table will show the position of the Limburg beds. 



Miocene. 

 A.. Bolderberg beds, see p. 178, seen near Hasselt. 



Upper Eocexe, 



B. 1. Nucula Loam of Kleyn Spavs^en, same ) Upper Limburg beds, — Rupelian 

 nge as clay of Rupelmonde and Boom. ) of Dumont, 



B. 2. Fluvio-marine beds of Bergb, Letben, ) Middle Limburg beds. — Upper 

 and otber places near Kleyn Spawen. ) Tongrian of Dumont. 



B. 3. Green sand of Bergb, N"eerepen, &c., [Lower Limburg Beds. —Lower 

 near Kleyn Spawen : Marine. ) Tongrian of Dumont. 



Middle Eocene. 



C. Lackeu and Brussels beds, witb num- 

 mulites, &c. : Louvaiu and Brussels. 



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

 series is separated in the abov 3 table, contains at Kleyn Spawen many of 

 the same fossils as the clay ol Rupelmonde and Boom, ten miles south of 

 Antwerp, and sixty miles N. W. of Kleyn Spawen. About forty species 

 of shells have been collected from the tile-clay worked on the banks of 

 the Scheldt at the villages above mentioned. At Rupelmonde, this clay 

 attains a thickness of about 100 feet, and much resembles in mineral 

 character the " London Clay," containiDg like it septaria or concretions of 

 argillaceous limestone traversed by cracks in the interior. The shells 

 have been described by MM. Nyst and De Koninck. Among them 

 Leda (or Nucula) Dcshayesiana (see fig. 167) is by far the most abun- 



Fig 167. 



Leda Deshayesiana. ISTyst. Syn. Nucula Deshayesiana, 



