70 SECTIONAL ADDRESSES 



The deposits which succeed the Great Chalky Boulder Clay (using 

 that term to include the Chalky- Jurassic Boulder Clay and the Chalky- 

 Neocomian Boulder Clay) yield the most satisfactory evidence known 

 to us of a widespread climatic change. The ice retreated from practically 

 the whole, if not the whole, of East Anglia, leaving here and there trails 

 and fans of sands and gravel and occasional lake-like areas, often several 

 square miles in extent, in which laminated clays and loams were deposited. 

 Some of these basins, like that at Hoxne, were connected with the existing 

 river-systems, others lay high on the boulder clay plateau ; all seem to 

 have become gradually silted up with sediment which, from its petro- 

 graphical character, is evidently the finer washed-out matrix of the 

 Great Chalky Boulder Clay. The deposits are laminated, but no true 

 varves have been found. In the present connection, however, the main 

 point of interest lies in their fossil-contents, which include leaves, pollen, 

 land and fresh-water shells, bones and teeth of the larger mammalia, 

 and the implements of Man. 



Chief among these ancient lakes are the basins at Ipswich (Foxhall 

 Road), Hoxne and Hitchin. The flora contained in the upper part of 

 the series of laminated clays indicates that the climate then diflfered but 

 little from that of the present day. Reedy fens and alder-cars bounded 

 the lakes, and elm, oak, birch, spruce, pine, and hazel formed the neighbour- 

 ing woodland. Beavers were to be found in the streams and the horse 

 and red deer roamed over the country. 



In the gravels and brickearths lying in the basins are found ' floors ' 

 of industries of Upper Acheulian type, a special feature being the beauti- 

 fully fashioned and entirely unrolled hand-axes. The succession at 

 Hoxne in particular consists of Chalky-Jurassic Boulder Clay overlain 

 successively by (a) brickearth containing temperate plants like those of 

 to-day, (b) a loam with dwarf birch and supposed arctic willow, (c) gravels 

 and brickearths with late Acheulian implements, mammoth, and reindeer, 

 (d) laminated clays with Early Mousterian implements and temperate plants 

 and animals, and, finally, (e) deposits like boulder-clay, and disturbed 

 gravels. While the successions at Ipswich and Hitchin are similar, 

 only at Hoxne is there found, below the Acheulian layer, a bed, already 

 referred to, containing the ' arctic ' plants, now considered to be evidence 

 of cold but not of arctic conditions. Thus between two temperate 

 climatic phases we find a cold oscillation, and this oscillation must be 

 placed just before the Upper Acheulian. Sealing up these lake-like 

 depressions are deposits of sand, gravel, and stony clay variously termed 

 ' trail ' and boulder clay. Rafts of a Chalky Boulder Clay actually 

 occur in the gravels, but may be in part derived. The great amount 

 of disturbance to which the uppermost deposits have been subjected 

 is a strong indication of the resumption of glacial conditions, especially 

 as there is in places a thin deposit of intensely Chalky Boulder Clay. 

 I cannot but regard the evidence for a post-Early Mousterian cold period 

 in East Anglia as firmly established, even if the phenomena are explained 

 as due to the slumping of snow and sludge rather than the work of ice. 

 A more general term than ' Upper Chalky Boulder Clay ' is desirable 

 for these variable deposits of post-Early Mousterian age, and I therefore 



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