738 ME. J. LOMAS ON THE INORGANIC [NOV. I9OO, 



delta-deposit of the Rhine, which attains such vast proportions in 

 the subsoil of Holland. The subsidence of portions of Holland and 

 of the North-Sea basin, which went on pari passu with the accumu- 

 lation of this delta, seems to have died out towards East Anglia: 

 the Icenian deposits becoming gradually thinner as we trace them 

 southward and westward. 



The Weybournian Crag occurring only north of the map 

 (fig. 3, p. 714), divided from the Icenian by the estuarine Chillesford 

 Beds, does not extend into Suffolk, and is probably, as explained 

 on p. 724, distinct from the shingle of Westleton and Dunwich, 

 which may be of Glacial age. 



Although a few species of mollusca found in the Red Crag which 

 seem characteristic of an earlier horizon may possibly have been 

 derived from Older Pliocene beds, it does not appear to me that 

 the Red Crag has been leavened by an admixture of Coralline 

 Crag forms. The mollusca of the boxstones which occur in places 

 at the base of both the Coralline and the Red Crags, equally 

 with the Eocene fossils found with them, are, however, derivative in 

 the Crag, as are the remains of Mastodon, and other mammals which 

 seem quite out of place in these comparatively recent deposits. 



The conditions under which the Newer Crag -beds originated seem 

 to exist at the present day in Holland, where sandy material 

 brought down by rivers into the sea has been thrown against and 

 upon the shore, together with the shells of marine mollusca, and 

 probably by winds from the west. From meteorological considera- 

 tions it seems possible that strong gales from the east may have 

 prevailed over the Crag area during the latter part of the Pliocene 

 Epoch. This would explain why shelly sand accumulated in such 

 enormous quantities on the East Anglian margin of the North Sea 

 at that period, while at the present day the eastern coasts of Norfolk 

 and Suffolk are almost wholly destitute of such debris. 



The so-called Forest-bed, with its southern fauna, indicates a 

 distinct change in climatal conditions, similar to that of the Inter- 

 glacial episodes of the Pleistocene Epoch, and should be separated, 

 on the one hand, from the Weybourn Crag, and on the other (as 

 urged by Prof. James Geikie l ) from the Leda-myalis Sands and 

 the Arctic Freshwater Bed. The latter two seem naturally to group 

 themselves together, and with the Glacial deposits. 



VII. Appendix. 



Report on the Inorganic Constituents of the Crag. 



By Joseph Lomas, Esq., A.R.C.S., F.G.S. 



Red Crag. 



For the purposes of this enquiry the proposed zones of the Red 

 Crag — Waltonian, Newbournian, and Butleyan — may be taken 

 together, as no essential differences in the contained minerals can 

 be detected. 



Very marked distinctions in colour are noticeable in different 

 1 ' Great Ice Age ' 3rd ed. (1894) p. 336, etc. 



