238 Geological Society. 



wards Antwerp, but within the Polder-belt, were conjectured, from 

 their composition and on other considerations, to have been derived 

 from sands carried inland away from dunes of the Boulder-forma- 

 tion period . The Los, which is of freshwater origin, resulted from 

 the annual depositions of melted snow-waters. The dispersion of 

 the Cailloux Ardennais was referable to another and earlier stage of 

 a period of cold, and when the axis of the country had a greater 

 relative elevation than at present. These views were supported by 

 reference to the coast-section at Sangatte. 



The Boulder formation proper is only slightly represented in 

 some of the sections about Antwerp. 



With respect to the Lower Kainozoic series, the author preferred 

 the divisions proposed by M. Dumont (Scaldesien and Diestien) to 

 the minute subdivisions of Sir C. Lyell and M. Nyst. The exceed- 

 ingly narrow vertical dimensions of the Crag, and the manner in 

 which, along the continuous sections now exposed, one bed of the 

 Scaldesien Crag replaces another, are new facts, and preclude any 

 systematic order of sequence, founded on percentage comparisons, 

 from local assemblages of fossils. 



The Antwerp Crag series presents two conditions of sea-bed : — a 

 deepish-water and life-zone formation, corresponding to the ooze- 

 depths of existing seas ; this is the Diestien of Dumont, or Lower 

 Crag : on an eroded surface of this, there occurs at Antwerp an upper 

 series of coarser sands, shingle, and gravel, together with much 

 which has been derived from the lower; this is the Scaldesien. 

 The change from one to the other indicates a change as to depth 

 over the Crag sea, and the result has been an admixture of the 

 characteristic materials of distinct sea-zones. 



The original boundary line of the Crag sea is traced, as also the 

 great breadth of the drift-sand zone, over the Belgian area ; this — ■ 

 coupled with the consideration that the Crag-sea waters on the 

 continental coast- line nowhere came in contact with any beds older 

 than Nummulitic, such as Tongrien and Bruxellien, even as high as 

 Denmark, whilst on the English side, from Suffolk north, its coast- 

 line was of chalk with flints — indicates a closed sea on the south, 

 since only by such an arrangement could the flint-gravel be carried 

 along. 



The differences between the Crag-fauna of England and of Bel- 

 gium were explained in accordance with bathymetrical distribution. 

 The Scaldesien beds of Antwerp contain an assemblage which is 

 composed in part of a littoral fauna, and in part of that of ooze- 

 depths. The Red Crag of Suffolk differs from the Scaldesien in 

 being more littoral in its forms, as also from containing the mate- 

 rials of a Bryozoan zone. 



The Bolderberg beds, which afforded M. Dumont his evidence in 

 favour of his " Systeme Bolderien," were shown to have been 

 wrongly interpreted, and to belong to the Crag-sea accumulations. 



