72 



Newport Half a mile south of the village is a pit exhibit- 

 ing sandy brick-earth, underlain by fine light sand, the latter 

 also enclosing mammalian remains. 



Passing now to the gravels which stretch northward from 

 Cambridge, we find them spread out over a wide extent of 

 country, bounded on the west by the long ridge of the Girton 

 and Observatory gravels, and on the east by the alluvium of the 

 present river. This sudden wide extension of the gravels may 

 be accounted for in two ways ; either it indicates the previous 

 existence of an estuary in which the deposits were spread out, 

 as Prof. Seeley believes ; or else it is due to the river having 

 continually cut back its eastern bank, so as to leave a series of 

 undisturbed gravels on its western side. 



It is true that the outspread of gravel between Cambridge 

 and Histon has somewhat the appearance of an estuarine 

 arrancjement ; at least it is difficult to conceive how some of it 

 could ever have been formed in any river channel. It may be 

 however that this is only the result of excessive subsequent de- 

 nudation, and the area appears to be highest in the centre 

 about Arbury, King's Hedges and Landbeach, the height of the 

 ground between the two latter places being given by Fitton as 

 55 feet above sea-level ; from this central line it slopes evenly 

 and gradually down to the present alluvium on the one side, 

 and irregularly towards Histon on the other, as if there had 

 been some slight local elevation over the intermediate tract. 



Again, one would not expect to find a watershed in a plain of 

 river-gravel ; but a marshy field between the old semi-circular 

 encampment called Arbury and the main road to Histon 

 appears to occupy such a position, the water soaking off eastward 

 and westward from this spot to supply ditches and streams 

 which flow respectively into the Cam and the Ouse. 



It is worth while noting these circumstances, even if they 

 cannot be held to prove any postglacial disturbance of the surface. 



The true explanation of this wide spread of gravel is 

 probably to be found in the second alternative, viz. that the 

 river has always had a tendency to encroach upon its eastern 

 bank, and has gradually changed the direction of its course 

 from N.W. to N. and finally to N.E. 



