Vol. 52.] PLIOCENE DEPOSITS OE HOLLAJSTD. 767 



III. The Geographical Conditions of the Anglo-Dutch Area 



DURING THE VARIOUS STAGES OF THE PLIOCENE EPOCH. 



In one of the maps accompanying this paper (PI. XXXIV.), I have 

 sketched hypothetically, and as far as the evidence will allow, what 

 I consider may have been the distribution of land and sea at the 

 different stages of the Pliocene era. I have taken the lines drawn 

 by M. Van den Broeck as representing approximately the southern 

 limits of the Diestien and Scaldisien basins. I have followed 

 Mr. Clement Eeid in connecting the former with Lenham, but I 

 have ventured to bend the line to the S.W. beyond that place, as a 

 suggestion of the manner in which the sea of the Coralline Crag may 

 have communicated with the Atlantic. I have shown the southern 

 limits of the sea of the Walton Crag as occupying a position similar 

 to that of the Scaldisien and Poederlien in Belgium, for it appears 

 probable that the elevatory movement which in that country carried 

 the shore of the Scaldisien sea to the north would in the same manner 

 have affected the English area. The sea of the Walton Crag may 

 possibly have extended over the district now occupied by the Sutton 

 and Butley deposits, traces of its former existence having been 

 removed by denudation, or being concealed below the water-line, 

 but it seems unlikely that it covered those parts of Norfolk in 

 which occur the fluvio-marine strata of the Upper Crag. 1 



The southern boundary of the Amstelien, and of the Upper Red 

 •Crag of Suffolk, is drawn to the north of that of the Scaldisien. 

 The Amstelien beds do not extend into Belgium, 2 and in Holland 

 they give indication of thinning out to the south, while in Suffolk 

 the Red Crag of Butley originated, if not as a beach or foreshore- 

 deposit, at any rate at no great distance from the coast. 



It appears that after the deposition of the Amstelien beds, that is, 

 at a period not later than that of the Norwich Crag, the subsidence 

 of the Dutch area was arrested, and land conditions were established. 

 It does not seem that any deposits representing the latest horizons 

 of the English Crag were found in these borings, as the eastern 

 margin of the Pliocene sea had been by that time shifted, in con- 

 sequence of the elevation of the area in question, to the west of the 

 present coast of Holland. Part of the western (the East Anglian) 

 portion of the Pliocene basin was still submerged, and from the strata 

 •there deposited some information may be gained as to the geo- 

 graphical conditions of this period. 



Mr. Wood and I formerly regarded the Norwich Crag as estuarine, 

 but I now think that it may have originated in a shallow bay, or 

 the embouchure of an estuary, 3 which, however, did not extend so 

 far southward as did the sea of the Butley Crag. The general, 

 though comparatively infrequent, occurrence of land and freshwater 



1 Some of the beds met with in Suffolk in the deep boring at South wold, 

 under the Norwich Crag, may possibly be of Red Crag age. 



2 M. Mourlon has kindly allowed me to examine the material obtained by 

 the officers of the Belgian Geological Survey from borings in the north of that 

 country, but I have been unable to detect the presence of the Amstelien beds 

 there. 



3 See Godwin- Austen, Quart. Journ. Geol. Soc. toI. vii. (1851) p. 129. 



