Cretaceous and Older Rocks in East Kent. 543 



axis of unrest, probably of Charnian affinity. This conception 

 receives further support from a study of the special characters 

 exhibited by the Wealden of East Kent and the nature of the 

 unconformity between these strata and the Mesozoic and Palaeozoic 

 rocks underlying them. 



When the composition of the sub-Cretaceous surface in East Kent 

 is investigated it is seen to consist, in the north-east, in the neigh- 

 bourhood of Walmestone, Mattice Hill, and Ebbsfleet, of Palseozoic 

 rocks (Middle Coal-measures). A little to the north of Ebbsfleet, in 

 the vicinity of Ramsgate, the sub-Cretaceous surface must be com- 

 posed of the outcrop of the Carboniferous Limestone. South-westward 

 of the outcrop of Middle Coal-measures, in the neighbourhood of 

 a N.W.-S.E. line passing through Stodmarsh, occurs an area where 

 the surface is composed of Bathonian. There can be no doubt that 

 these Bathonian strata once extended further north-east and were 

 overlapped in their turn by the Oxfordian, Corallian, and 

 Kimmeridgian (see Section, p. 548), but these Upper Jurassics, and 

 the Bathonian itself in part, have been removed by the severe pre- 

 Cretaceous and early Cretaceous denudation to which the East Kent 

 area was subjected. This sub-Cretaceous outcrop of the Bathonian 

 is followed south-westward successively by outcrops of the Oxfordian, 

 Corallian, and Kimmeridgian. In the south and west, westward of 

 Ellinge, the Portlandian follows the Kimmeridgian in normal 

 sequence, but makes no feature at the sub-Cretaceous surface owing 

 to its being concealed by an overlap of the Purbeck. It appears 

 likely that this overlap is an unconformable one. At Dover the 

 coarse, freshwater Wealden gravels rest directly upon an irregularly 

 worn surface of Kimmeridge Clay, but Mr. Lamplugh considers 

 that there is at least a strong probability that marine sedimentation 

 continued in this area into Portlandian times, though it is less likely 

 that the Purbeck Series was ever developed here. 1 At Ellinge the 

 Portlandian is missing, the Purbeck resting directly on the 

 Kimmeridgian. It would appear, then, that the Purbeck cuts across 

 the Portlandian on to the Kimmeridgian in this area. Further, at 

 Brabourne the Purbeck strata comprise clays and sands with 

 a strong green tint (perhaps due to the presence of glauconite, which 

 is so often associated with non-sequential deposition), and contain 

 also a remarkable breccia of peculiar composition, similar in character 

 to that seen in the Purbecks of Hartwell, Bucks, and elsewhere, the 

 occurrence of which appears to be associated with local uncon- 

 formities. 



It is unfortunate, from the point of view of the cartographer, that 

 so many of these borings in East Kent were made by chisel, and that 

 there is, in several instances, doubt concerning the precise sequence 

 in the Jurassic strata passed through. It is beyond doubt, too, that 

 this area has been largely affected by faulting, and the application of 

 cartographical methods to the available data becomes in consequence 

 a matter for careful consideration. It does not appear possible, in 

 the present state of our knowledge, to do more than show the positions 



1 Lamplugh & Kitchin, On the Mesozoic Bocks in some of the Coal Explora- 

 tions in Kent (Mem. Geol. Surv., 1911, p. 20). 



