184 Reports and Proceedings — 



other preglacial gravels was considered, and the Westleton Beds 

 were referred to a period subsequent to that of the formation of the 

 Southern Drift. 



The influence of the meeting of the earlier Wealden axis with that 

 of the folding which produced the escarpments of central England 

 was discussed, and it was suggested that the result would be the 

 genesis of the Thames-valley and river. 



The following summary gives the results of the author's inquiry 

 as developed in the other parts of the paper. He holds : — 



1. That the Westleton shingle ranges from Suffolk to Oxfordshire 

 and Berkshire, rising gradually from sea-level to 600 feet. 



2. That the lower Tertiary strata were coextensive with this 

 shingle. 



3. That the upraising of the Westleton sea-floor, with its shingle, 

 preceded the advance of the glacial, deposits, and that the latter 

 became discordant to the former when traced westward, occupying 

 valleys formed after the rise of the Westleton Beds. 



4. That the Tertiary strata and Westleton Beds on the north 

 border of the Chalk-basin were continuous until the insetting of the 

 Glacial period, when they were broken through by denuding agencies. 



5. That none of the present valleys on the north of the Thames 

 Tertiary-basin date back beyond the Preglacial period. 



6. That the same date may be assigned to the Chalk-, and pro- 

 bably to the Oolite-escarpments. 



7. That in the Thames-basin, besides the Northern Drift, there is 

 a Southern Drift derived from the Lower Greensand of the Wealden 

 area, and from the Chalk and Tertiary strata formerly extending 

 partly over it. 



8. That during the Diestian period the Weald was probably partly 

 or wholly submerged, and that between this and the insetting of 

 the Glacial period, the Wealden area and the Boulonnais underwent 

 upheaval, resulting in the formation of an anticlinal range from 2000 

 to 3000 feet high. 



9. That from the slopes of this range the materials of the Southern 

 Drift were derived, and spread over what is now the south side of 

 the Thames basin. 



10. That this denudation commenced at the time of the Bed Crag, 

 and went on uninterruptedly through successive geological stages. 



11. That consequently, though the Southern Drift preceded the 

 Westleton shingle, the two must at one time have proceeded syn- 

 chronously. 



12. That the valley-system of the Wealden area dates from 

 Pliocene times, — the initial direction of the transverse valleys from 

 Preglacial times, — and of the longitudinal valleys from Glacial times. 



13. That the Thames basin results from the elevation of the Weald 

 and the flexures of the Chalk and Oolites of the Midland counties, 

 and dates from a period subsequent to the Westleton Beds. 



14. That the genesis of the Lower Thames similarly dates from 

 early Pleistocene times, whilst its connection with its upper tribu- 

 taries and the Isis, which possibly flowed previously north-eastward, 

 took place at a rather later period. 



