242 NEOZOIC TIME. [CHAP. XII. 



by a movement of elevation and exposed to the action of 

 tidal currents. 



The beds known as Coralline Crag are now limited to a 

 small area in Suffolk around and between the estuaries of 

 the Deben and the Aide, but they are evidently mere rem- 

 nants of a formation which had once a far wider extension. 



The St. Erth Beds, which occur at a height of about 100 

 feet near Hayle in Cornwall, are regarded by Mr. C. Eeid 

 as approximately of the same age as the Coralline Crag. 

 They consist of fine clays and sands, in which many fossils 

 have been found, none of the shells having a northern 

 range, while some of them are southern species which have 

 not been found elsewhere in Britain. 



Newer Pliocene. Coming now to the Newer Pliocene 

 series, we may consider the Bed and the Norwich Crags 

 together, as they are generally believed to be contempora- 

 neous deposits. The Red Crag of Suffolk rests either on 

 the London Clay or on an eroded surface of the Coralline 

 Crag, and it is surmised that the latter had been raised 

 into the condition of an actual land- surf ace and again sub- 

 merged before the deposition of the Bed Crag upon it. 

 The Norwich Crag rests chiefly upon the Chalk. 



These newer crags underlie nearly the whole of eastern 

 Suffolk and Norfolk, extending westward as far as Sud- 

 bury in the former, and to Cringleford, near Norwich, in 

 the latter county. They, in turn, suffered much from 

 erosion at a later period, and we may assume that their 

 original boundary lay considerably to the west of their pre- 

 sent limits ; the probable position of this boundary and, 

 inferentially, of the sea in which they were deposited, is 

 indicated by the line B B, in fig. 7, p. 240. 



The Bed Crag is divisible into two zones or stages : (1) 

 a lower set of shelly and current-bedded sands, largely 

 composed of the detritus of the Coralline Crag ; (2) an 

 upper set of horizontally stratified sands and clays (the 



