1852.] LYELL BELGIAN TERTIARY FORMATIONS. 309 



3. Micaceous Sands o/Henis, Geulem, Klimmen, ^c. 



On the right bank of the Meuse opposite Maestricht, the most 

 eastern locahty where I saw the Limburg tertiaries, they consist of 

 whitish and yellowish micaceous sands without fossils. I observed 

 them at Geulem, about five miles N.N.E. of Maestricht. The 

 uppermost part of the section in that place exhibits loess and gravel, 

 25 feet thick, below which is 20 feet of white and greyish sand, 

 followed by yellowish sand with mica, 10 feet thick, and lastly 

 Maestricht chalk. I learn from M. Bosquet, that at Klimmen, on the 

 same side of the Meuse, near Fauquemont, are white sands in a simi- 

 lar position, about 30 feet thick, in which he found Venus incrassata 

 and some other fossils ill-preserved, but none which showed distinctly 

 whether these sands are referable to the Lower or Middle Limburo- 

 series. ^ 



I observed similar beds at Henis, immediately below the green 

 marls of the middle division (c. Table VIII. p. 304). The sands also 

 at Predikheerenberg, near Louvain, mentioned by M. Dumont as 

 underlying the Rupelmonde clay of that locahty, may belong to the 

 same division, but, in the absence of strata containing Ostrea venti- 

 lahrum and other characteristic lower Limburg shells, it seemed to 

 me impossible to settle the true age of such sands. 



4. Relation of the Rupelmonde and Boom Clay to the Upper 

 Limburg Beds. 



An important notice was read to the Royal Academy of Brussels 

 by M. Dumont, in 1851, " On the geological position of the Rupelian 

 clay*," in which he announced the discovery at Predikheerenberg 

 and Lubbeck, near Louvain, of clay with septaria, precisely resembling 

 in mineral character that of Rupelmonde and Boom, and containing 

 several characteristic species of fossil shells, as Leda Deshayesiana, 

 Nucula Chastelii, and Astarte Kickxii. This schistose clay reposes 

 on sand, in which casts and impressions of fossils referred to Pecten 

 HoeninghausiiyPectunculusfossilis, Kon. (P. terebratularis,ljdimk.)y 

 and Cyprina Nystii, all of them middle Limburg shells, have been met 

 with. 



I visited the localities myself, in company with M. de Koninck, and 

 have no doubt that the dark schistose clay at Lubbeck and some 

 neighbouring places corresponds to that of Rupelmonde. It is 

 covered by the Diest sands, and rests on other sands which belong 

 to some part of the Limburg beds below the " Nucula-loam " (Table 

 VIII. p. 304) ; the state of decomposition, however, of the organic 

 remains found in them makes it somewhat rash at present to assign 

 to the sandy beds an exact position in the series. 



The middle Eocene strata, or Brussels beds, are seen near the base 

 of the hill of Predikheerenberg, not far from the village of Pare, and 

 in the suburbs of the town of Louvain, near the Tirlemont gate. 



* Acad. Roy. de Belgique, torn, xviii. no. 8. des Bulletins, lue le 2 Aout 1851. 



