Vol. 68.] STAGE IN THE TALLET OF THE KIYEE LEA. 217 



triangle with sides measuring approximately 2 miles, a mile and a 

 half, and three-quarters of a mile. In any case there are two 

 points, a mile and a half apart, at both of which extensive exposures 

 of the Arctic Bed may be seen.^ 



Much of the Arctic deposit is laminated and distinctly water- 

 laid. At the same time, an examination of its fauna and flora 

 shows that it is not a truly lacustrine deposit formed in a per- 

 manent lake. I think that the greater part of the deposit represents 

 the silting of drifted material in water ponded up by some 

 temporary barrier — this barrier being not improbably formed by 

 the accumulation of ice-floes. 



A little below the site of these discoveries, a hill, named Higham 

 Hill, stands up almost in the fair-way of the valley. In addition 

 to this, the features presented by the 50-foot contours appear 

 to me somewhat suggestive. These contours close in across the 

 valley at a point a little below Enfield Lock. If one follows them 

 in the down-stream direction from this point, one finds that they 

 gradually widen out until they are a mile and three-quarters 

 apart at Angel Road. Prom this point they widen out rapidly to a 

 space of nearly 2| miles immediately above Higham Hill : the space 

 between the 50-lbot contours opposite to that hiU closing in again 

 to a mile and a quarter. 



Thus a time of flood would give a wide expanse of comparatively 

 quiet water immediately above Higham Hill. This would, it 

 seems to me, tend to favour the accumulation of ice-packs at the 

 foot of the obstruction ; these ice-packs might spread across the 

 river, and eventually form a temporary barrier across the narrower 

 channel below. This is, of course, only to be understood in the 

 light of a suggestion. But the breaking-down of such a suppositi- 

 tious barrier, with the accompanying breaking-up of the river-ice, 

 would supply an adequate cause for the disturbances which the 

 Arctic Bed is seen to have undergone. 



I have not succeeded in finding any evidence of glaciation among 

 the stones ; the conditions were probably not sufficiently rigorous 

 to produce this. At the same time, the bones are not infrequently 

 scratched with straight scorings 4 or 5 inches long. These 

 surface-scratchings are particularly well seen on the mammoth- 

 tusk from the Tottenham Marshes, to which reference has already 

 been made. Such scratches would doubtless be formed under the 

 conditions which have been suggested. 



Certain portions of the deposit, instead of being laminated, are 

 composed of unstratified stony clay ; the stones are subangular 

 flints, stained black. In one of the isolated masses presenting this 



1 [Mr. Arthur Wrigley and myself are now investigating some further plant- 

 bearing beds, lower down the Lea Valley, in the neighbourhood of Temple 

 Mills and Hackney Wick. These, although belonging to the Low-Level Drift, 

 show differences in their plant associations from the beds described in this 

 paper, but I am unable to speak more definitely at present. — S. H. JV., 

 June 12th, 1912.] 



