Revieics — Mesozoic Mocks of Kent Coal Exploration. 133 



Beds, Sandgate Beds, possibly Hythe Beds, and Atherfield Clay are 

 distinguished ; but a less amount of Weald Clay than that given by 

 Mr. Whitaker is now recorded. It is not surprising to those who 

 have had to deal with well-borings, that difficulty is experienced in 

 correlating the subdivisions of the Hastings Beds with those shown on 

 the Geological Survey maps. Purbeck Beds are now introduced, and 

 an illustration is given of a peculiar breccia similar to a bed exposed 

 in the same formation at Hartwell and Haddenham in Buckinghamshire. 

 The Portland Beds rest abruptly on the Kimeridge Clay, with indications 

 of erosion, whereas at Pluckley and Penshurst these formations merge 

 gradually one into the other. The Upper Corallian yields a band of 

 "millet-seed iron-ore", as at Dover, but much reduced in thickness. 

 Tlie succession below is like that at Dover, with more Oxford Clay, 

 subdivided into the Maricb, Renc/geri, and Ornatus zones, and there is 

 a possible representative of the Puller's Earth or Fullonian formation. 

 The Upper Lias, as noted by Dr. Kitchin, includes not only the Communis 

 zone, but also part of the Jurensis zone. Rhynchonella tetrahedra is 

 definitely recorded from the Middle Lias, while the Lower Lias 

 includes representatives of the Capricornus, Jamesoni, and possibly 

 Oxynotus zones. ]S^o traces of E-hsetic beds were discovered, but there 

 was evidence of a good deal more Triassic marl and conglomerate than 

 previously recorded, and these red rocks repose on mudstone, possibly 

 of Devonian age. 



At Pluckley the boring, commenced in Weald Clay, proved an 

 unbroken sequence down to the Kimeridge Clay, and at Penshurst, 

 commenced in Hastings Beds, a similar sequence was encountered. 

 In both cases Purbeck and Portland Beds are now distinctly recognized 

 and separated, with considerable increase in thicknesses at Penshurst, 

 but it is admitted that the Portland Sand is represented in the Upper 

 Kimeridge Clay. At Penshurst there are " greater thicknesses of 

 Lower Wealden and Purbeck strata than have been proved at any 

 other place within the Weald"., Of Kimeridge Clay 622 feet was 

 penetrated, probably not more than one-half of the total thickness, as 

 the Penshurst site appears to lie near the central part of an old 

 depression where the accumulation of sediment reached its maximum, 

 and it is remarked that upon the thickness of this formation largely 

 depends the success or failure of attempts to reach the Palaeozoic floor 

 in the south-east of England. An instructive diagram (plate iv) shows 

 the arrangement and succession of the strata from Penshurst to Dover, 

 and on it thick black lines indicate planes of original horizontality. 

 From these data the earth movements can be studied, and it is 

 apparent that the Wealden dome is "an anticline formed upon, or 

 within the area of, an earlier syncline ". 



Di'. Kitchin has contributed some judicious remarks on the testimony 

 afforded by fossils obtained from cores and shafts, the depths recorded 

 being no positive indication of vertical range, while at many horizons 

 fossils may occur in proximity to cores that were barren. Observations 

 are made on the influence of sedimentary conditions and on certain 

 species that appear to have a wide range in time. The value of 

 recording generic names alone need not be questioned, as they may 

 help to indicate the conditions under which strata were deposited. 



