256 NEOZOIC TIME. [CHAP. XII. 



The contents of the Norwich Crag (see p. 244) plainly 

 show that the rivers which entered the shallow sea came 

 from the westward and carried debris which had been 

 derived from the central parts of England. From the great 

 depth of the Crag at Southwold (147 feet), and at Beccles 1 

 (80 feet), where the muddy nature of the deposits is also 

 remarkable, we might suppose that one of these rivers 

 traversed what is now the valley of the Waveney, this 

 being continued westward into that of the Little Ouse, 

 which may then have been occupied by a river coming from 

 the region of Bedford and Bucks, where the Ouse now 

 takes its rise. This stream, however, could hardly have 

 carried the Carboniferous fossils which have been found in 

 the Crag, and unless these were drifted along the coast 

 from some far northern locality, Derbyshire and Leicester- 

 shire are the nearest and most probable sources. The 

 valley of the Trent at once suggests itself as a possible 

 channel of transport, for we know that the ancient course 

 of this river was not that which it now follows, but through 

 the Jurassic escarpment along the valley now occupied by 

 the Witham into the basin of the Wash. 2 Further, its 

 drainage system is such that its tributaries could derive 

 all the stones which have been recorded as occurring in the 

 Norwich Crag. 



Bearing in mind these facts and the general considera- 

 tions mentioned on p. 254, there is nothing improbable in 

 the suggestion that the breach in the Chalk escarpment 

 which is now occupied by the Wash was initiated by the 

 combined forces of the rivers Trent, Witham, Welland r 

 and Nen, before this escarpment had receded to anything 

 like its present position. There is every reason to suppose 

 that in later Pliocene time all these rivers traversed the 



1 Woodward, " Geology of the Country around Norwich," p. 156. 



2 See " Quart. Journ. Geol. Soc.," vol. xxxix. p. 606, and " Geology 

 of the Country around Lincoln," Mem. GeoJ. Survey. 



