On the Newer Pliocene Period in England. 385 



watershed between this system and that of the great Ouse in South 

 Bucks, as well as by the valley of the Colne, Lea, and E-oding, and 

 over the lower part of the watershed in South-east Essex. Its- 

 entry into the North Sea was by the valleys of the Blackwater, 

 Gipping, and other Essex and Suffolk valleys, the entry by the Yare 

 and Waveney being far out beyond the present coast-line. He also 

 traced, by similar evidence, the extent to which the sea entered the 

 Trent system after the ice vacated it. This line of gravel (after 

 allowing for the case that the elevation of the junction of the gravel 

 beneath the clay represents that of the sea-bottom, while that over 

 the clay more nearly represents that of the sea-top), he showed to 

 correspond with that of the junction of the gravel beneath the clay 

 so far as this is not destroyed in the parts where the ice did not 

 shrink into the valleys ; and it also agrees with this line, sup- 

 plemented by the amount of rise in the interval where the ice did 

 so shrink. Along the south-western edge of the clay this line of 

 gravel, subsequent to the clay, falls from near 400 feet in Bucks 

 to 150 feet in South Essex ; whence northwards along the south- 

 eastern edge it falls uniformly to Ordnance datum in central East 

 Suffolk, and probably continued to fall to 100 feet or so further to 

 the extreme point where the ice from the Yare valley entered the 

 North Sea, far beyond the present coast. Along the north-western 

 edge of the formation this line falls northwards in a corresponding 

 way to that on the south-eastern edge, save that, starting there from 

 near 350 feet, it does not fall below, if even quite down to, Ordnance 

 datum near the Wash. He then traced the extent to which the sea 

 on the west, deepening in that direction in accordance with the 

 original depression of Stage II., entered the valleys of the area 

 covered by the ice of the Chalky Clay as this vacated it ; the carrying 

 out through the Well and and Avon valleys of the red and white 

 chalk spoil of the Bain- Steeping trough, and its deposition in the 

 Cotteswold gravel up to a high level, coming from the Avon system 

 over the Gloucestershire water-parting into the valley of the Even- 

 lode, a part of the Thames system. 



All river-gravels north of the point where the line of gravel over 

 the clay sinks below Ordnance datum, he regards as concealed below 

 the alluvium, and at depths proportional to the fall of that line. 

 Examining in detail the grounds for the contrary opinion heretofore 

 held by himself and by geologists in general, that the great sub- 

 mergence succeeded the principal glaciation of England, he rejected 

 that opinion ; and no longer regarding the basement clay of Hol- 

 derness (with its ancient molluscan facies) as identical with the 

 Chalky Clay, but as moraine synchronous with the Till of Cromer, he 

 considered the gravels with shells at extreme elevations in Lancashire 

 to have preceded all glacial clays but these, and to have escaped 

 destruction by the advance of the ice during the rise only at the south 

 end of the western slope of the Pennine chain, those on the eastern 

 having been wholly swept away, but that gravels were deposited 

 on the east side of the Pennine after the dissolution of the Chalky - 

 clay ice up to the reduced height of the sea-level at that time, and 

 so far as the ice of the purple clay allowed the sea to come. He 

 then relinquished the opinion formerly held by him that the passage 



