Page:VCH Kent 1.djvu/54

 A HISTORY OF KENT that the uppermost portion of the Folkestone Sands should be classed with the Gault,^ In their prolongation inland the stony bands of the Folkestone Beds soon disappear, so that to the westward of Saltwood the division consists for some distance almost entirely of sharp ' false-bedded ' sands with irregular lines of ironstone. West of the Medway however, near Ightham, the sands again include impersistent masses of extremely hard glauconitic siliceous stone ('Ightham Stone' or 'Firestone'), and a similar rock was found in the much attenuated Folkestone Beds passed through in the colliery sinkings at Dover. The coarser sand-grains of the deposit are frequently extremely well-rounded and polished, as though by long-continued attrition in the shifting sandbanks of the current-swept sea floor, and these smooth- worn grains are particularly noticeable in the band containing the phosphatic nodules near the top of the sands. This band probably marks a falling off in the supply of sandy material as the waters became deeper and the shore-line more distant, and foreshadows the approach of the conditions under which the Gault was afterwards deposited. Where unmodified by ' superficial ' accumulations, the Folkestone Beds make a thin sterile soil, and such tracts are only partly cultivated. SELBORNIAN Gau/t— With the deepening and expansion of the sea basin the sand-bearing currents ceased to reach the district, and only the finer muddy material sank through the quiet waters to this part of the sea- floor. This sediment accumulated to form the Gault, a more or less calcareous clay, in which are embedded the beautifully preserved shells and other remains of marine organisms of the period that gladden the heart of the collector who examines the famous section exposed on the coast at East Wear Bay near Folkestone. For the splendour and variety of its fossils this locality is unrivalled in Kent and is scarcely equalled elsewhere in the British Islands. They include many species of Ammonites, Hamites and other allied cephalopods, with Nautilus and Belemnites ; bivalve and univalve shells in abundance and of wide variety ; crustaceans of several kinds ; small corals ; many foraminifera ; the teeth and bones of fish and reptiles ; and a few plant remains.^ Many of the shells still possess their original pearly iridescence, and can be separated from the soft clayey matrix with all their delicate markings and ornamentations intact. Being usually impregnated with iron pyrites however, they decay rapidly when exposed to the weather, so that it is only in freshly-cut sections on the shore or at the foot of the cliff that they can be obtained in good condition. They are more abundant ' For recent discussion of this point, with description of the 'zone of Am. mammillalus' at Folicestone, see Mem. Geol. Survey, 'The Cretaceous Rocks of Great Britain,' i. 43, 73. 2 The reptilian and fish remains of the Gault are described in the context : see article ' Palsonto- logy,' P- 3'- 12