498 S. V. WOOD, JUN., OK THE NEWER 



and SO continued until the ice disappeared. I have therefore given 

 some examples of the way in which we find the moraine in the 

 Gipping valley. 



Fig. XX. (which is about a mile south of the line of Sect. I. a) 

 seems to show very clearly the passage of the moraine down the 

 vaUey, and the ploughing out of the sand by it. 



In fig. XIX. (which is three miles north of this in the same 

 valley, and is given to illustrate Stage lY.) the Chalky Clay, plunging 

 into the valley, as shown in fig. I. a, rests on the same thin bed of 

 dark-coated flints of Lower Eocene age over chalk which is present 

 in fig. XX. The figure is as the Section appeared when I copied it, 

 in the year 1864 ; but I am informed by Mr. W. Whitaker that the 

 Chalky Clay may now be seen in one place to be forced under this 

 Eocene bed. 



The thickening of the ice in the valleys and its shrinkage from 

 the position it occupied when, by pushing its mud-bank before it, the 

 moraine was laid over c, and the change from that mode of deposit 

 to the cutting-out method, is not confined to East Anglia,but is shown 

 generally along the outer edge of the formation ; as, for instance, on 

 the heights on the western side of the Lea valley at Einchley, in the 

 east of Sheet 7, the clay rests on c, as it does also on the opposite 

 side, in the extreme north-west corner of Sheet 1, and so eastward 

 through the channel bounding the small island in that part ; but 

 from this position it plunges some way down the western side of the 

 Lea valley in Sheet 1, cutting out c entirely. The same thing occurs 

 with the valley of the Welland, in the north-west corner of Sheet 52 

 and south-east of 63, d resting upon c on the heights, as at Des- 

 borough Railway Cutting, but in the valley bottom at Harborough, 

 on the Lias. In the case of the Avon valley, in Sheet 53, it rests 

 on c at the elevation of about 380 feet in the Kilsby tunnel, and 

 many surrounding sections on the plateau south of Rugby, mentioned 

 by Mr. Wilson ; but in the valley-bottom at Eugby, 100 feet below 

 this, it rests on the Lias*. 



It is not, however, merely where thus shrinking into valleys that this 

 change from deposition over gravel to the cutting it out occurred 

 towards the end of the formation ; for the same thing appears where 

 the ice advanced against the water-partings between the Ivel and 

 Ouzell in the east of Sheet 46, and the Ouse and Thames systems in 

 that sheet and in the east of 45 ; and which partings, though shown 

 open in Map 2, had at the close of the formation emerged. 



Thus it seems to me that though Nordenskiold describes the change 

 from the mud-bank to that of the cutting-out mode to be continually 

 occurring in Greenland and Spitzbergen, this change took place in east 

 Suff'olk and Norfolk at one particular stage, which was when about 

 80 feet out of the total rise of the land which occurred during the 

 formation of the Chalky Clay that I shall deduce in describing 

 Stage Y. remained to be accomplished ; though nearer the ice source, 

 as, e.g., in Sheet 53, this did not occur until the close of the deposit, 



* Quart. Joarn. Geol. Soc. vol. xxvi. p. 200. Eeport of Rugby School Nat. 

 Hist. Society for 1873. 



