part 1] A>~>'1YERSARY ADDJiEss OF THE PRESIDENT. lxxvii 



that all the main divisions of the Mesozoic sequence are represented 

 above the Palaeozoic floor in the southern half of the section ; but 

 of these, only the Upper Cretaceous rocks remain in the northern 

 part, every formation below the Gault having tapered out north- 

 wards, partly by thinning and partly by unconformable relationships,, 

 both within and between the Jurassic and Cretaceous divisions. 

 The structure, indeed, is precisely that foretold with astonishing 

 insight by R. A. C. Godwin-Austen in his classical paper submitted 

 to this Society in 1S55, 1 where, in discussing the probable range 

 of the Oolitic Series, he says : — 



1 These considerations suggest the probability that the Oolitic series of 

 depositions may be wanting over an area part of which is now represented by 

 our south-eastern counties and along a line to the north of the Wealden 

 denudation. To what extent the Oolitic group may exist beneath the Wealden 

 and Cretaceous groups of Kent, Sussex and Surrey, is a more difficult ques- 

 tion ; but the continuity of the old ridge [" the axis of Artois "] beings 

 granted, we may infer that, relatively as to its breadth, it exercised along our 

 area a like influence to that it had along its continental course, and that, 

 whilst the ascending members of the group were brought up against it by a 

 process of successive overlap, as in the Boulonnais, so also they were abraded 

 and denuded from above downwards, as has happened there.' 



It will be seen from the figure (fig. 1) that just as the upward 

 curve of the Cretaceous strata marks participation in the visible 

 anticline, so the downward curve of the Jurassic strata suggests- 

 relationship to a hidden syncline. 



In this section the Jurassic-Lower Cretaceous wedge has ex- 

 panded southwards from zero under the Thames valley to a thickness 

 of 1784 feet at Brabourne, a mile or two south of the Chalk 

 escarpment, with good evidence that the maximum has not been 

 nearly reached, since a boring at Penshurst near Tollbridge, 2 some 

 8 miles south of the Chalk escarpment but still on the northern side 

 of the anticline, starting low down in the Wealden Series, proved a 

 thickness of 1867 feet for portions of the Wealden and Upper 

 Jurassic sequence which are represented at Brabourne by only 

 about 200 feet. Moreover the Lower Kimineridge Clay, not 

 reached at Penshurst, but proved to be over 600 feet thick in a 

 recent boring near Battle, 8 is less than 200 feet thick at Brabourne. 



1 'On the Possible Extension of the Coal-Measures beneath the South- 

 Eastern Part of England ' Q. J. G. S. vol. xii (1850) pp. 65 GO. 



2 Fully described in the above-cited Memoir k On the Mesozoic Books, Ac' 

 Mem. Geol. Surv. 1911, pp. 66- 77. 



3 See 'Summary of Progress of the Geological Survey for 191G. Appendix 

 III— On a Deep Boring made in 1907 9 at Battle. ' 



