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. 5
