294 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 19, 



On tlie whole, in mineral character and aspect, they reminded me 

 much of the ferruginous division of the Lower Green Sand in the 

 South-east of England. Occasionally flint-pebbles are intermixed, 

 and sometimes concretions of hydrate of iron are conspicuous. In 

 several localities thin beds of clay separate the sands. I observed 

 cross or false stratification on a large scale in these beds east of 

 Louvain. 



I found the hydrate of iron or limonite exceedingly abundant 

 about two miles west of Louvain, on the road leading to Brussels, in 

 the hill called " Montague de Fer,' ' where bright green grains are 

 mixed with the quartzose sand. 



The only spot where organic remains have been as yet observed is 

 three miles east of Louvain, near Kesseloo, a place which I visited in 

 company with M. Nyst, and where we collected casts of a species of 

 Turbinolialy tolerably abundant. In the same locality casts of the 

 Terehratula grandis of Blumenbach {T. variabilis. Sow.) have been 

 discovered. From the occurrence of this shell, a species very cha- 

 racteristic of the crag of England, together with casts of other genera, 

 M. Nyst inclined many years since to the opinion that the Diest 

 sands belonged to the crag. I have shown the casts in question, 

 presented to me by M. Nyst, to Mr. Davidson, whose accurate know- 

 ledge of the Brachiopoda is well known, and he entertains no doubt 

 of the correctness of the determination of this large Terehratula, not 

 only from the form of the shell, but from the impressions of the pecu- 

 liar processes which are so prominent in the interior. Terehratula 

 grandis occurs in the Coralline and Bed Crags of Suffolk, and I have 

 seen it in extraordinary abundance in the crag of St. George de Bohon, 

 near Carentan, in Normandy. 



In M. Dumont's Report of 1839 I find the Diest sands given as 

 next below the Campinian or Antwerp crag series, and he cites casts 

 of Antwerp shells, Pec^w/xcwZw^ variabilis. Sow. {P.pilosus or P.gly- 

 cimeris, Linn.), and a supposed fragment of Solen ensis, as having 

 been found by M. Van Beneden. All evidence of relative age, de- 

 rived from position, seems to be wanting, or is confined to the fact 

 that the Diest sands overlie the Bolderberg beds to be mentioned in 

 the next section. Without the aid of the organic remains, we could 

 not have decided whether the Diest sands were allied to the Antwerp 

 crag, or to the Bolderberg deposit, or were quite independent of 

 both. Whether they are more nearly related to the (7ra^ noir, or to 

 any other of the Antwerp crags before mentioned, is as yet un- 

 certain. 



The Diest sands are very conspicuous in Belgium and French 

 Flanders, as forming the capping of hills throughout a great part of 

 the country where the tertiary strata occur. I first saw them at 

 Cassel, near Dunkirk, capping the chain of hills which extends from 

 Cassel into Belgium. On Mont Noir, in particular, the mass 

 crowning the hill consists partly of gravel with a ferruginous cement, 

 and exhibits hollow tubular concretions of hydrate of iron, which in 

 detached masses, as I saw them lying in a gravel-pit, resembled a 

 pile of cannons, or a heap of large iron cyUnders used for gas-pipes. 



