IXXIV PK0CEED1XUS OF THE GEOLOGICAL SOCIETY. [vol. lxxv, 



assumption that the floor of Pakeozoic rocks under the South-East 

 of England might be nearly flat ; and not deeper, even perhaps 

 shallower, beneath the Weald than at Kentish Town, where it had 

 been struck at 927 feet below O.D. He showed that, granting this 

 assumption, the northward dip of the Grault, from its estimated 

 position, before erosion, of 2000 feet above O.D. on the central 

 axis of the Weald, to its known position at more than 900 feet below 

 O.D. at Kentish Town, was fully accounted for by the thickness of 

 the formations that originally lay beneath the Gault in the Weald 

 but were absent at Kentish Town. If the paper had .been written 

 after the Sub-Wealden Boring had reached its full depth, Topley 

 might have fortified his argument by citing the further 1900 feet 

 of Upper and Middle Jurassic rocks there proved beneath the 

 Weald and wanting at Kentish Town ; and from later borings he 

 could have added still more to his excess-balance. 



Clearly, in putting forward these views Topley realized, and was, 

 I believe, the first to realize, the essential peculiarity of the 

 Wealden structure — that the anticline does not persist in depth. 1 

 His idea that the dome might be nothing more than a great pile 

 of heaped-up sediments, with sloping banks, gained little accep- 

 tance ; and it is, in fact, disproved by the composition of some of 

 the deposits : but his inference that the anticline occurs only in the 

 higher formations has been abundantly verified. 



During the past twenty years we have gained much new infor- 

 mation about the underground geology of the Weald from deep 

 borings, particularly in East Kent, where the search for coal has 

 led to a systematic probing of the strata down to the Palaeozoic 

 floor. I have fortunately had the opportunity, in collaboration 

 with my colleagues Dr. F. L. Kitchin and Mr. J. Pringle, of 

 examining for the Geological Survey the cores or other material 

 obtained from the Mesozoic rocks in most of these borings. Some 

 of the results of this examination have already been published 2 ; 



1 The disappearance of the anticline underground is indicated, but without 

 comment, in a figured section across the Weald illustrating Mr. W. Whitaker's 

 paper ' On some Borings in Kent ' Q. J. G. S. vol. xlii (1886) pi. iii. p. 46 ; also 

 in a similar section in H, B. Woodward's ' Jurassic Rocks of Britain ' vol. v, 

 Mem. Geol. Surv. 1895, fig. 144, p. 298. 



2 ' On the Mesozoic Rocks in some of the Coal-Explorations in Kent ' by 

 G. W. Lamplugh & F. L. Kitchin, Mem. Geol. Surv. 1911 : also ' The Under- 

 ground Range of the Jurassic & Lower Cretaceous Rocks in East Kent ' 

 Appendix IV to ' Summary of Progress for 1916 ' Mem. Geol. Surv. 1917. 



