252 PB0CEEBINQ8 OF THE GEOLOGICAL SOCIETT. [Jan. 24, 



banks of. the Scheldt and on the slopes of the broad ditch of the north 

 citadel, where it is full of small shells of the common Cardium and 

 Scrobicularia ; land and fresh-water shells also occur. The whole 

 district of Zeeland, as the name implies, is of this sea mud. The 

 *'a,rgile d'Ostende " is of the same age, with the same shells. Along 

 the whole of this coast the Polder-mud passes below the present sea- 

 level, as may be seen occasionally oif the Ostend coast at low water, 

 where the compact mud resists the action of the sea. The composi- 

 tion of the Ostend Polders differs a little from that of those to the 

 north, in the large proportion of calcareous matter, which has pro- 

 bably been derived from the waste of the chalk. The Zeeklei of 

 the l^orth Holland coast is also Polder. 



The Polder formation indicates a change of level, or of relative 

 elevation of the land, of small amount, but of remarkable imifor- 

 mity, from Ostend to the coast of Hanover ; it also corresponds with 

 alluvial accumulations and mud flats to be met with in suitable 

 situations about our own coasts, whether of the English, Irish, or 

 German Seas. 



The Dunes, or great sand hills, along the coast south-west of 

 Ostende, as well as those of North Holland, have all been accumu- 

 lated on the Polder mud, and since the change of level. 



The Polder mud differs from the accumulations of the present 

 coast-line of Belgium and Holland, which consist of fine siliceous 

 sands, and must have been deposited in brackish water lagoons, 

 into which the rivers discharged, and which were separated from 

 the open sea by sand-banks. 



6. Terrestrial Surface. — From specimens in the Antwerp Museum 

 it would appear that when a breach is made in the Polder mud, a 

 terrestrial surface with large trees is exposed. The like was met 

 with in the excavations for the new docks, consisting of rich peat. 

 This old land-surface is to be seen at low water, beneath the Polder 

 mud. In like manner it underlies the Zeeklei of Holland; and 

 much, probably, of the surface of peat or old fen of Belgium and 

 Holland (Hooge Yeenen), above the level of the Polders, is merely an 

 upward and inland extension of the same surface of plant-growth. 



In the Antwerp collection are some Mammalian remains, which 

 were obtained at West Capellen, the extreme seaward point of the 

 Island of Walcheren, when the. sea had made a breach there. Mr. 

 Busk recognized the perfect lower jaw, tibia, and other bones of a 

 young Elejohas 2^r{migenii(s,'d\so two teeth ot Bhinoceros tichor}ii7ms. 



Belgium for the most part belonged to that particular zone which 

 was a limit to the area of the last great north circumpolar depres- 

 sion ; and its superficial geological phenomena belong to the subaerial 

 agencies of the glacial period ; such are the " Cailloux Ardennais '* 

 and the Loss, as well as the Sables de Campine. 



At some time antecedently to that of greatest submersion, the 

 line of Artois, and of the Ardennes (like our own Wealden), had been 

 placed at a much greater elevation than at present, with respect to 

 Brabant and the Hesbaye ; the position of the Loss shows this. The 

 surface may have been brought to its present levels partly by de- 



