22^ PROF. J. E. MARK 0>" THE [vol. lxxv. 



Pleistocene period was succeeded by one of general aggradation- 

 Even should the Corbicula Beds in the immediate vicinity of 

 Cambridge prove to be newer than the Barrington deposits (and I 

 recognize the possibility of this being the case), the Hippopotamus 

 beds of Barrington are generally recognized as being of an early 

 date. But these beds, several miles upstream from Cambridge* 

 are at a height below 70 feet above 0. D., whereas the beds con- 

 taining implements of Mousterian type at the Traveller's Best. 

 Huntingdon Boad, are more than 80 feet above the same datum. 

 These facts in themselves indicate aggradation. Indeed, aggra- 

 dation to the extent of at least 20 feet is indicated by the thick- 

 ness of the deposits in the Traveller's Best Bit itself, and as these 

 deposits occur at a level below the present base of the pit in a 

 westerly direction, aggradation to the extent of about 30 feet is- 

 indicated, and a further aggradation of about 15 feet would account 

 for the difference of level between the Milton-Road Corbicula- 

 Beds and the deposits at the top of the Traveller's Best Bit. 



Further minor aggradations during the period of general 

 erosion following the main aggradation are indicated. Thus, after 

 the lowering of the water-level to the height of the base of the 

 beds which I have described as the newer Barnwell-Yillage Beds, 

 a certain amount of aggradation caused the accumulation of 

 these beds at heights of about 30 to 45 feet above O.D. Subse- 

 quently to this there was erosion to an unknown depth, forming a 

 channel the base of which passes below the level of the Cam 

 alluvium at Barnwell Station, and another period of aggradation 

 was marked by the accumulation of the Barnwell-Station Beds in 

 this channel. 



The occurrence of aggradation in early Baheolithic times is 

 borne out by many observations made outside the area under 

 consideration in this paper. I hope to consider this in greater- 

 detail elsewhere. Here I may call attention to the frequent 

 occurrence of Lower Baheolithic implements, some quite unworn,, 

 at or below fen-level, as, for instance, at Shrub Hill. Feltwell. 

 The deposits in which these occur are frequently some way below 

 the well-known deposit of High Lodge, Mildenhall, containing 

 implements of Le Moustier type. 



As pointed out in my paper in the Broceedings of the Cam- 

 bridge Philosophical Society, the period of aggradation would 

 correspond with that during which the March and Nar- Valley 

 marine beds were deposited, the latter being at present found at 

 least 50 feet above sea-level. 



The occurrence of climatic oscillations is also indicated by the 

 deposits. I do not propose to discuss here the questions as to the 

 relationship of the Paheolithic period to that of the accumulation 

 of the Chalky Boulder-Clay. 



Taking into account only the deposits found in the immediate 

 vicinity of Cambridge, there seems proof of a warm period during, 

 the time when Hippopotamus lived in this district. Succeeding 

 this was a colder period, marked by the incoming of the mammoth 



