ILFORD AND WANSTEAD. 165 



sufficient to provide ice-rafts). This conclusion appears to be 

 the only one open to the field geologist, and to a certain 

 extent it is supported by the palaeontological evidence. 



In my opinion, however, the Middle Terrace drift as a whole 

 (including the brickearths) shows a very different state of things 

 in climatic conditions. I have argued in my paper that whether 

 we view this group of the Palaeohthic deposits from a lithological 

 or from a palaeontological standpoint, we have to regard it as 

 representing a period of comparative equability, probably similar 

 to that obtaining in these islands at the present day. 



A point of interest with regard to the physical geography of 

 the brickearth period is dealt with. From the occurrence of 

 Scrobicularia pipevata at Ilford, of Paliidestrina ventrosa at Crayford, 

 Grays, and Ilford, and of Littorina riidis at Crayford in the Middle 

 Terrace brickearths of those places it is argued that the Thames 

 whatever it may have been in earlier or later parts of the 

 Pleistocene epoch could hardly have been then a tributary of 

 the Rhine. On the contrary it must have then possessed an 

 estuary of its own, probably situated not very far to the east 

 of that of the present day. The upper beds of the Middle 

 Terrace drift show similar contortions to those observed in the 

 High Terrace series. The conclusion to be drawn is then 

 obvious, viz., that they have been contorted by river ice. From 

 this it would appear that comparatively severe conditions came 

 on once more towards the close of the Palaeolithic period. 



The following tabular statement of the Pleistocene deposits 

 of the Thames is given in the conclusion of the Geologists' 

 Association paper : — 



1. High Terrace Drift ) ^, , ,-. , .... ^ , , 



2. Middle Terrace Gravels ^^^^^ Palaeolithic. Cold 



(in part) \ . P^^^°d- 



3. Middle Terrace Gravels ) Newer Palaeolithic. Genial 



(in part) & Brickearths ) period. 



4. Trail (Contorted Drift } Close of Palaeolithic Period. 



series) > Cold period. 



A list of the more important papers and works relating to 

 the Pleistocene deposits of the Ilford district is appended to the 

 paper. 



Martin A. C. Hinton. 

 Janmuy 27th, 1900, 



