768 MR. P. W. HARMER ON THE [Nov. 1 896, 



shells in beds of Norwich Crag age seems to show that a river 

 discharged into this bay, and the occasional presence of specimens of 

 Cyrena fluminalis, a species now inhabiting the Nile, 1 as well as of 

 mica and Rhenish pebbles, indicates that this river flowed from 

 the south. 2 An interesting indication of the shore-line of the Crag 

 sea occurs at Hoxne, in the Waveney Valley, where, at the most 

 westerly point to which the Norwich Crag has been traced, the 

 Chalk rises suddenly in the form of a cliff. 3 



The enlarged map of East Anglia (PI. XXXY.) shows the western 

 limit of the area within which exposures of the Norwich Crag are 

 found, and it does not seem probable that the sea of this period 

 extended to any great distance beyond it. Its eastern margin cannot 

 be traced, as in that direction the Crag beds dip below the water-level. 4 



In the typical section of Norwich Crag at Bramerton, there is an- 

 upper bed, similar lithologically to the lower one, but containing 

 a rather more boreal fauna, the northern species, Astarte bor edits, 

 being more common in it, while littoral forms are comparatively, and 

 fluviatile exceedingly, rare. This somewhat more recent and 

 deeper water-bed implies a slight subsidence, and this would have 

 carried the bay farther to the west. Hence, some of the deposits 

 near the margin of the area ; or those, like that at Aldeby, from 

 which freshwater shells are absent, or nearly so ; or the beds which 

 immediately underlie the Chillesford Clay, may be of the age of the 

 upper rather than of the lower bed at Bramerton. It is difficult, 

 however, to find any marked palseontological difference between 

 the various deposits of the Norwich Crag series, and I have not 

 attempted on the map to distinguish between them. 5 



The Chillesford Clay, the deposition of which followed that of 

 the Norwich Crag, has been from the very first a veritable apple of 

 discord, and the controversies that it has excited have by no means 

 ceased. Mr. H. B. Woodward, studying this formation in the 

 district near Norwich, where it is not well represented, and seems 

 sometimes to be interstratified with other beds, has come to the 

 conclusion that it does not represent any definite geological horizon ; 

 but against this, his colleague, Mr. Whitaker, who worked in Suffolk, 

 where such difficulties do not exist, protests. Mr. Clement Ileid, 



1 Cyrena fluminalis is also found in Thibet and China (S. V. Wood, Jun., 

 Quart. Journ. Geol. Soc. vol. xxxviii. 1882, p. 694) and in some of the rivers of 

 Central Asia. 



2 The presence of land and fluviatile shells, together with Rhenish pebbles, 

 etc., in the Norwich Crag over so large an area as that from Aldeburgh to 

 the Bure Valley, seems to show that the rivers of Central Europe were, at this 

 period, working themselves round to the western side of the Pliocene basin. 



3 See Clement Eeid, ' Pliocene Deposits of Britain,' p. 112. 



4 It is much to be regretted that H.M. Geological Survey does not attempt 

 more systematically to clear up doubtful points of this kind by boring. Every 

 square mile of the Belgian Geological Survey maps contains information 

 obtained in this way. 



5 Mr. Wood and I formerly called the Norwich Crag deposits which appeared 

 to be more recent than the lower bed at Bramerton ' Chillesford Crag.' It 

 seems better merely to refer any which can be shown to be so to an upper zone 

 of the Norwich series. 



