754 ME. F. W. HARMEE 01* THE [Nov. 1 896, 



was closed to the north may be regarded as an open question, but 

 the almost total absence of boreal shells from that formation seems 

 in favour of the latter view. If this was so, the combined movement 

 of elevation and depression which followed the deposition of the 

 Older Pliocene probably created a land-barrier which prevented the 

 further access of warm currents from the south, while communica- 

 tion with northern seas was opened up, and this was probably one 

 of the causes of the gradual change in the facies of the molluscan 

 fauna which is characteristic of the Upper Crag. 



In Belgium this elevation caused the sea to retreat in a northerly 

 direction. Diestien strata occur in that country about 25 miles 

 farther south than do the shallow- water Scaldisien deposits which 

 rest on them, 1 implying in M. Van den Broeck's opinion a north- 

 ward shifting of the shore-line previously to the deposition of the 

 latter, while before the upper beds of the English Crag came into 

 existence the sea had altogether retired from Belgium. A similar 

 change in the southern margin of the Newer Pliocene basin, due to 

 the same cause, may be traced in East Anglia. The oldest deposits 

 of the Upper Crag, namely, those at Walton, are found only at or near 

 that place, 2 that is at the southern extremity of the Crag area, the 

 succeeding horizons of Sutton, Butley, Norwich, and Weybourn, as 

 pointed out by Mr. Wood and myself many years ago, being repre- 

 sented by beds occurring successively in positions farther north. 



At Antwerp, the Newer Pliocene strata (Scaldisien and Poederlien) 

 are thinly represented, attaining a maximum thickness of about 

 12 or 15 feet, and are exposed only below the water-level. They 

 increase in thickness to the north, and in Holland are covered by 

 a great mass of still more recent Pliocene and Pleistocene beds, 

 which rapidly thicken in a northerly direction, and reach at 

 Amsterdam, if my classification of these deposits be correct, the 

 extraordinary thickness of more than 1000 feet. Dr. Lorie has 

 given, in the works before alluded to, descriptions of the strata met 

 with in borings at Goes, Gorkum, Utrecht, Arnhem, and Amsterdam, 

 as well as careful lists of the fossils discovered at different depths. 

 He recognizes at these places, in addition to the recent alluvium on 

 the one hand, and the Rupelien which was reached at Goes, on the 

 other, the presence of three formations, namely, ' Quaternaire/ Scal- 

 disien, and Diestien. Mr. Clement Reid expressed the opinion in 

 1889 that the Scaldisien deposits of Belgium represent, not the 

 whole of the Red Crag, but its lowest or Walton stage only, and 



1 M. Van den Broeck says, ' Le Scaldisien tout entier est lui-menie un depot 

 essentielleinent cotier et littoral.' 



2 I cannot agree with Mr. Reid (' Pliocene Deposits,' etc. p. 85) that the bed 

 at Beaumont, 5 miles from Walton, described by Mr. J. Brown, of Stanway, 

 50 years ago, should be referred to the Upper Red Crag. With very few 

 exceptions the shells recorded from th»t locality occur at Walton or in the 

 Coralline Crag, and most of them abundantly. Two northern species are men- 

 tioned, however, Astarte borealis and Scalaria similis (grcenlandica), which have 

 not been found at Walton ; but the former is not a Red Crag shell at all, having 

 made its first appearance in the Norwich beds. Mr. Wood had great doubt 

 whether these specimens had been correctly identified. The sinistral variety of 

 Trophon antiquus, the characteristic shell of the Walton horizon, occurs at 

 Beaumont, but not the dextral form. 



