GEOLOGY 



HASTINGS BEDS 



Though the greater part of the outcrop of the Hastings Beds occurs 

 in Kent and Sussex, the series also occupies a few square miles in the 

 extreme south-eastern corner of Surrey, there forming the pleasant rising 

 ground to the south of the Medway valley. Limited though this area 

 is, it is sufficient to show nearly the whole sequence of the series, in- 

 cluding the various subdivisions known as the Ashdown Sand, the 

 Wadhurst Clay, the Lower Tunbridge Wells Sand, the Grinstead Clay, 

 and the Upper Tunbridge Wells Sand. The general characters and aver- 

 age thickness of these strata have been already given in the table, and need 

 not be repeated. The fossils of these beds, which are most abundant in 

 the clay-bands, consist chiefly of freshwater shells of the genera Cyrena, 

 Unio and Paludina, along with the minute oval valves of Cypris, a small 

 fresh or brackish water crustacean. In Sussex many plant remains have 

 also been found, chiefly ferns and cycads, and from the same county have 

 been obtained the teeth and bones of gigantic extinct reptiles of ungainly 

 aspect, such as Iguanodon, Hylaosaurus, Cetiosaurus, etc., and the remains 

 of turtles and of fish. 



According to the usual classification the Hastings Beds constitute 

 the lowest division of the Lower Cretaceous system, and they are thus 

 shown in the table and on the map. Recently, however, it has been 

 urged in several quarters 1 that the fossils indicate a closer affinity to the 

 Jurassic system than to the overlying Cretaceous, and consequently that 

 we should include the Hastings Beds with the Jurassic. This is a matter 

 which is still under discussion, and we therefore need not enter further 

 into it. 



WEALD CLAY 



As the Hastings Beds sink down northward towards the Medway 

 valley they pass beneath the thick mass of Weald Clay which extends 

 over almost the whole of the southern part of the county. The outcrop of 

 this clay constitutes the low gently undulating plain of the Weald which 

 spreads out from the foot of the hilly ridges dominating it to the north- 

 ward in which the more durable overlying formations terminate. The 

 fossils of the Weald Clay are chiefly freshwater shells and cyprids, re- 

 sembling those of the Hastings Beds, and they indicate that, as in the 

 former case, the deposit represents an accumulation of mud and silt 

 brought down into a lake or land-locked estuary by a river draining an 

 extensive land. This land is generally supposed to have lain chiefly to 

 the westward, but there is really much doubt as to its position, as 

 evidence recently obtained tends to show that the more strictly fresh- 

 water conditions prevailed in the eastern part of the Wealden area, 

 while towards the south-westward there are indications of an estuary; 



1 See Prof. O. C. Marsh, Geol. Mag., dec. 4, vol. iii. (1896) p. 8 ; A. S. Woodward, 

 Geol. Mag., dec. 4, vol. iii. (1896) p. 70; and A. C. Seward, Nature, vol. liii. (1896) 

 p. 462 ; see also G. W. Lamplugh, Geol. Mag., dec. 4, vol. vii. (1900) p. 443. 



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