482 S. V. -V^OOD, JUN., ON- THE NEWER 



In Stage II. I have shown that the great submergence extended 

 from East Norfolk in an increasing degree southwards, and with 

 still greater increase westwards ; and at the conclusion of the descrip- 

 tion of that stage I have attempted to arrive at the amount per mile 

 of this increment. Now the line of gravelly sea-bottom in the 

 respective regions at the time when the Chalky Clay was deposited 

 over it, outside the broken line in the map, is shown by the eleva- 

 tion at which the junction of that clay with the gravel c takes 

 place ; and this will be found substantially to agree with the 

 increment of submergence traced in Stage II., so far as intervening 

 irregularities in this bottom do not interfere with the case, this 

 junction being illustrated by figs. X. to XIII. 



Beginning with fig. XIII. at about 40 feet above Ordnance 

 datum, on the North-Suffolk coast in Sheet 67, this junction rises 

 to about 80 or 90 feet in the centre of Sheet 66 (see fig. IX.). From 

 Sheet 67, south-westwards to the north-east of Sheet 1, it rises to 

 100 feet in the north-west of Sheet 48, to about 170 in the north- 

 east of Sheet 1 (see Margaretting cutting in fig. YI.), and about 

 300 in the south-east of Sheet 7. The westerly rise of this line is 

 greater, in accordance with the increment of submergence, in 

 that direction, which is traced in Stage II. ; for from 100 in the 

 north-east of Sheet 48 it rises to between 260 and 300 in the 

 south-east corner of Sheet 46 (whence fig. XI. is taken), and 

 thence to about 380 in the north centre of Sheet 53, and if I am 

 right in my interpretation of Messrs. Crosskey and "Woodward's 

 section (fig. XYII.), to 460 in Sheet 62. Irregularities in the 

 depth at which the sea-bottom, represented by this junction of 

 the gravel c with the clay, lay below the sea- surface interfere 

 locally with the uniformity of this rise of the line; as,* for 

 instance, this junction at the north end of sect. VI. is at about 

 150 feet, and in the north of the Roding Channel further west, and 

 so round to the north-west side of the small island divided by it 

 from island 3 at very little more, whereas in the south-east of 

 sheet 7, at Finchley, it is from 280 to 300 feet *, w^hich is a greater 

 difference than the westerly increment would cause. The height 

 of the gravel e above c, in fig. XYIL, shows that the bottom there 

 also was at one place about 80 feet below the sea-surface. The 

 north-east of Sheet 46 also would seem originally to have been a 

 deep place if the gravel at Arlsey and Biggleswade be that marked 

 c ; but I think such is not the case, for I failed to find any section 

 showing it under d. 



If we take the position of the clay d representing the moraine 

 as indicative of that of the icef? we can see that with the depres- 



* From the delineation of the gravel in Sheet 7 of the Greological Survey 

 Map, d would appear to be underlain by c all round Finchley ; but 1 found the 

 Chalky Clay resting in places on the London Clay when the cuttings of the Edge- 

 ware Railway were in progress. Most oP the gravel also shown as "pebble" is 

 the older part of c, being that called by Prof. Huglies, in vol. xxiv. of the 

 Journal, the " gravel of the higher plain," which had to a great degree emerged 

 before the ice reached it. 



t The view to which the earher study of the subject led me was, that the 

 Chalky Clay represented moraine extruded under the sea, or left there as the 



