C— GEOLOGY 69 



it lies side by side with it in Lincolnshire, Norfolk and Cambridgeshire, 

 and was regarded by him as reflecting the different outcrops along the 

 strike of which the Great Eastern Glacier travelled. 



No Chalky-Neocomian Drift has been encountered in the area of the 

 Cromer Moraine ; indeed, from Weybourn eastwards, it is not seen 

 again until it appears, interdigitating with the Chalky-Jurassic Boulder 

 Clay, at Scratby, near Ormesby, north of Yarmouth. The line of demar- 

 cation between the two facies of boulder clay, having passed south of 

 Nonvich, sweeps north-eastwards and then northwards. The absence 

 of the Chalky Boulder Clay in the Cromer district suggests that the ice 

 had rounded some obstacle which prevented its direct passage over 

 northern Norfolk. There was no high ground to form such an obstacle, 

 for the Cromer Moraine was not then in existence. One is therefore 

 tempted to infer that the ice which produced the Cromer Till, and which, 

 on the evidence of its erratics, had passed down the east coast of England 

 to the Norfolk coast, lay in the way. 



Before leaving the problem of the Cromer Till and Contorted Drift, 

 I must make reference to the implements found in association with these 

 deposits. Unfortunately, finds of Chellian implements have been very 

 few and the provenance of all but one is a matter of inference. As I 

 have discussed the evidence in detail elsewhere, and given references 

 to the appropriate literature, I will here only repeat the general con- 

 clusions. If the workmanship of the hand-axes in question be accepted 

 as Chellian, and if the implements came from undisturbed Cromer Till, 

 then the probability is that they were picked up from the surface (perhaps 

 a land-surface) of the Cromer Forest-bed or other Pliocene deposits, 

 or of the Norwich Brickearth, by the oncoming Cromer Till ice. In 

 that event the Chellian industry of Cromer would be of pre-Chalky 

 Boulder Clay age and would be separated from the Acheulian by the 

 glaciation which produced that Boulder Clay. The intimate association 

 of the Chellian and Acheulian implements in many river-gravels and 

 the gradualness of the change in the technique of flaking are not neces- 

 sarily arguments against an intervening glaciation ; further, when Chellian 

 and Acheulian implements are found together elsewhere, the former are 

 commonly much more abraded and scratched than the latter. Indeed, 

 the fact that the majority of the Chellian implements found throughout 

 England are as a rule rolled and usually occur in the oldest implement- 

 bearing gravels suggests that they may have been derived from a land- 

 surface at a time when a marked change of conditions resulted in torrential 

 floods. Evidence supporting this view is found in the Whitlingham 

 deposits, to be described later. 



In the Cromer district Acheulian flakes and axes have been found 

 in gravels lying above the Contorted Drift (the so-called river-gravels 

 at West Runton and the Cannon-Shot gravels of the Ridge). These 

 implements are probably derived, but if they are unrolled and in situ, 

 as has been claimed, the underlying Contorted Drift into which the 

 gravels are eroded must be pre-Acheulian, that is, the disturbances are 

 probably due to the ice-sheet which produced the Great Chalky Boulder 

 Clav. 



