Vol. 68.] STAGE IN THE VALLEY OF THE EIVEE LEA. 219 



indicated are such as are only found to-day within the Arctic 

 Circle, although, it must be understood, not very far within it ; 

 certainly less rigorous than the present state of Spitsbergen. 

 Broadly speaking, the evidence brings the present climate of Lapland 

 down to the site of London. This is a very important difference 

 in climate, and one which deserves the name of Arctic or Glacial. 

 There can be little doubt that, under these conditions, all the upper 

 reaches of the mountain-valleys of this country would be occupied 

 by ice. How far the ice might or might not spread over the 

 plains, I will make no attempt to define. It is not contended that 

 the conditions would compare with those under which the Chalkj' 

 Boulder Clay or Cromer Till were formed. 



As may be seen from Dr. Lewis's report on the flowering plants 

 (pp. 229-30), some portions of the Arctic Bed at Bonder's End 

 consist of little else than the matted debris of the Arctic willow, 

 the Arctic birch being present in less amount. Although, during 

 the past eighteen months, enormous quantities of the Arctic Bed 

 have been carefully searched as the very extensive excavations 

 have proceeded, no trace of the wood or leaves of any bigger tree 

 has yet been found. One would not like to assert that no bigger 

 tree existed in the Lea Valley at this time, but it is quite certain 

 that if any such did exist, they were comparatively scarce. 



Other parts of this country, particularly south of the Thames, 

 may have been under forest : this one cannot say. But unless 

 we imagine the Lea Vallej^ to have been exceptional, extensive 

 areas of the southern part of England must have greatly resembled 

 the tundra of I*^orthern Europe, although less flat and marshy. 

 That is to say, a bleak, almost treeless region, largely covered by 

 moss when not under snow, and, with little more considerable 

 in the Avay of vegetation than the stunted bushes of the Arctic 

 willow and the Arctic birch, even these being half hidden in the 

 growth of moss. 



If it be desired, for convenience of reference, to give a name 

 to this stage of the Pleistocene, I would suggest that the term 

 * Bonder's End Stage ' would be an excellent one. 



IV. The CoKEELATioisr or Pleistocene Deposits. 



We maj now consider the important question of correlation. 



There are, in my opinion, only two lines of evidence upon which 

 to depend in defining the minuter subdivisions of age in the Pleisto- 

 cene Period. These are, firstly, the stratigraphical succession, and, 

 secondly, the human industries based upon that succession. 



Upon the continent of Europe ElepJias antiquus is taken as indi- 

 cative of the Chellean stage. But, to cite only one instance, the 

 Clacton bed, which is a purely ElepJias-antiquus deposit, can be 

 proved by the stratigraphical succession of the local river-drifts, 

 and of the human industries which they contain, to be post-Chellean ; 

 indeed, in all probability, post-Mousterian. The Mammalia can 

 show us the greater differences between Pliocene, Pleistocene, 



Q. J. O. S. No. 270. 11 



