PLIOCENE PERIOD JK EIT&LAlfD. 479 



would give a southerly increment, on the eastern side of England, 

 of 2'6 feet per mile. As, however, there was an unknown 

 depth of water over Cromer Hill, we must compare the elevation 

 of the gravel where it stands against contiguous unsuhmerged 

 summits, as it does at Well Hill, on the flanks of the Chil- 

 tern and Marlborough hills, and on the eastern slope of the 

 Cotteswolds, with its elevation at Moel Tryfaen. Owing to the 

 uniformity of the level along the north Downs, through Sheets 8 and 

 12, this increment from Well Hill comes out at a little more than 

 3'5 feet only ; hut from the Chiltern and Marlborough hills it is a 

 little over 4*4 feet ; and if we take the limit (750 feet) above which 

 no actual beds of gravel occur on the Cotteswolds, as the limit of 

 'submergence in that part, it gives the same figure. A mean of these 

 figures gives very nearly 4 feet per mile for the westerly increment ; 

 and if we reckon at that rate of decrease eastwards from Moel Try- 

 faen to Cromer, it would show a submergence at the latter place of 

 430 feet ; but this, from the evidences traced in stage Y. of the 

 amount of the rise during the Chalky Clay, is, I think, more than 

 was the case. From those evidences, the depression at Cromer 

 would appear to have been little more than 300 feet, which would 

 allow upwards of 150 feet depth of water above the general sur- 

 face of the Contorted Drift, ^. e. the parts where this has not 

 been forced up by the contorting agency; and this would be 

 sufficient for such false bergs as I have supposed, from JN'or- 

 denskiold's description, those must have been which carried the marl 

 masses, to float and ground in. Probably, therefore, 4-5 feet per 

 mile is as near to the truth as we can get for the westerly incre- 

 ment. If we take 300 as the limit at Cromer, and compare it with Well 

 Hill, which is distant from Cromer 120 miles, it gives the southerly 

 increment of depression as a little under 2'2 feet per mile. On the 

 western side of England the increment of submergence, instead of 

 being- from north to south, as it is in the east, is the reverse ; and 

 the distance from Bramshaw, in fig Y., to Macclesfield being 160 

 miles, there is a northerly increment along this line of between 4 and 

 5 feet per mile ; and with this the position oi 6' on the Cotteswolds 

 at 750 feet agrees. I shall collate these calculations with those 

 derived from the evidence afforded by the elevation of the junction- 

 line of the gravel c with the Chalky Clay over it in Stage III., and of 

 the gravel e over the Chalky Clay in Stage Y. 



Stage III. The Middle Glacial Sand and Gravel and the 

 Chalky Clay. 



Eig. II. (PL XXI.) is a reduction on nearly the true scale of that 

 at page 376 of vol. iv. of the Memoirs of the Geological Survey, and 

 exhibits the position of the gravel of ^orth Hants described in Stage 

 II. relatively to the Wealden excavation ; and in order to show the 

 extension of the gravel northwards from the patch at Caesar's Camp in 

 this figure, I have added fig. III., constructed by myself, in which, 

 unavoidably, the vertical scale is considerably in excess of the 

 horizontal. 



