572 Reports and Proceedings. 



tlius generally concealing that deposit, which manifests itself only in 

 the form of occasional protrusions through these later formations, 

 but which they consider constitutes, though thus concealed, the main 

 mass of the two counties. 



The authors also describe a glacial bed as occurring at various 

 localities in the bottom of some of these valleys, and which in one 

 case they have traced under the Middle Glacial. This they regard 

 as having been formed in the interval between the denudation of the 

 valleys and their subsequent submergence beneath the Middle Glacial 

 sea ; and inasmuch as such valley -bed invariably rests on the Chalk 

 in a highly glaciated condition, they attribute its formation more 

 probably than otherwise to the action of glaciers occupying the 

 valleys during an interglacial interval of dry land. They also 

 suggest that if this was so, it is probable that the forest and mam- 

 maliferous bed of Kessingland, instead of being coeval with the pre- 

 glacial one of the Cromer coast, may belong to this interglacial 

 interval — that is to say, to the earliest part of it, before the glaciers 

 accumulated in the valleys, and when the climate was more tem- 

 perate, any similar deposits in these interglacial valleys having 

 been for the most part subsequently ploughed out by the action of 

 the glaciers. 



In discussing the subject under the third head the authors point 

 out the many perplexing features which are connected with the 

 position and distribution of the Middle Glacial formation ; and 

 while they admit that as to one or two of these the theory which they 

 offer affords no explan-ation, they suggest that the theory of this 

 formation^'s origin which best meets the case is as follows, viz. : — As 

 the country became resubmerged, and as the valley glaciers retreated 

 before the advancing sea, the land-ice of the mountain districts of 

 North Britain accumulated and descended into the low grounds, so 

 that by the time East Anglia had become resubmerged to the extent 

 of between 300 and 400 feet, one branch of this ice had reached 

 the borders of the counties of Norfolk, Suffolk, Essex, Herts, and 

 Bedford, ploughing out and destroying any Lower Glacial beds that 

 had been deposited over the intervening counties upon which it 

 rested, and over which we ought otherwise, having regard to the 

 depth of the earlier submergence under which they were accumu- 

 lated, to find them, but do not. The Middle Glacial formation, 

 consisting of sand and gravel, they attribute principally to the action 

 of currents washing out and distributing the morainic material, 

 which was extruded on the sea-bottom by this land-ice ; that ice 

 itself by keeping out the sea over all the country on which it rested, 

 which was then below the sea-level, preventing the deposit of the 

 Middle Glacial in those parts. The termination of this current 

 action was accompanied by increased submergence, and by a gradual 

 retreat of the land-ice northwards to the mountain districts, until 

 Britain was left in the condition of a snow-capped archipelago, from 

 which eventually the snow disappeared and the land emerged. To 

 the moraine extruded from the base of this ice and into deep water 

 they refer the origin of the Upper Glacial Clay, the moraine 



