216 MR. S. H. WAEEEN" ON A LATE GLACIAL [June I9I2, 



with a change in climatic conditions. 'No such evidence was obtained, 

 and I think it probable that the three beds seen in vertical succes- 

 sion were parts of the same deposit which had been floated, or 

 thrust, one over the other by subsequent disturbance. 



It is true that some slight differences in the flora were observed 

 in the three collections, but these are not more conspicuous than are 

 noticed in other samples of the Arctic Bed, which varies greatly 

 within short distances, both in lithological character and in its 

 organic remains. 



When Dr. ¥. J. Lewis visited Ponder's End pit with me, 

 he was impressed by the similarity of the physical features of 

 the Arctic Bed to those which are referred to ' ice-raft action * in 

 the Scottish deposits. It may be that the agency of ice is too 

 frequently called in as an explanation of any difiiculty. It seems 

 to me, however, in the case of the Arctic Bed of Ponder's End, that 

 its physical features, taken in conjunction with its boreal fauna 

 and flora, must render such an explanation not only probable but 

 inevitable. 



Shortly after I had discovered the Arctic Bed at Ponder's End, 

 some mammoth and rhinoceros-remains were brought to me by a 

 workman, who stated that they were found in a temporary excava- 

 tion on the Tottenham Marshes, at a spot near the oil-cloth factory. 

 The material adherent to the remains was, so far as one could judge, 

 identical with the Arctic Bed at Ponder's End. It also yielded 

 seeds and mosses in the same manner as that bed: although, as 

 the material had dried, the remains were unfortunatel}- not in a 

 satisfactory state for determination. Dr. E. J. Lewis could only 

 say that the genera present, such as Potamogeton, were also common 

 at Ponders End. 



One of these mammalian remains consisted of a well-preserved 

 tusk of Elephas ijrimigenius, measuring 3 feet 6 inches along the 

 curve. The dark staining and condition of this tusk is the same 

 as that of the mammalian bones found within the Arctic Bed at 

 Ponder's End ; it difters greatly from the condition of bones found 

 in gravel, sand, or brickearth. 



At the same time, I can give no personal verification of the 

 locality, although a discovery that I have since made renders it 

 probable that this may be correct. 



Another large excavation, which belongs to the North London 

 Ballast Company, is situated close to Angel Road Station, at a 

 distance of about a mile and a half lower down the valley than the 

 Ponder's End pit. This pit is in the same stretch of Low-Level 

 gravel, and it shows an admirable section of the Arctic Bed. Here 

 the features which it presents are similar to those that have already 

 been described. In one part of this pit, some thin laminae of peat 

 were seen intercalated Avith sand : this material proved to be 

 particularly rich in seeds. 



Thus, if we accepted the indirect evidence of the mammoth- 

 remains from the Tottenham Marshes, this would give three points 

 at which the Arctic Bed is present. These three points form a 



