Upper Neocomian.

FOLKSTONE AND HYTHE BEDS.

(FIGURE 277. Nautilus plicatus, Sowerby, in Fitton’s Monog.)

(FIGURE 278. Ancyloceras gigas, d’Orbigny.)

(FIGURE 279. Gervillia anceps, Desh. Upper Neocomian, Surrey.)

(FIGURE 280. Trigonia caudata, Agassiz. Upper Neocomian.)

(FIGURE 281. Terebratula sella, Sowerby. Upper Neocomian, Hythe.)

(FIGURE 282. Diceras Lonsdalii. Upper Neocomian, Wilts. a. The bivalve shell. b. Cast of one of the valves enlarged.)

The sands which crop out beneath the Gault in Wiltshire, Surrey, and Sussex are sometimes in the uppermost part pure white, at others of a yellow and ferruginous colour, and some of the beds contain much green matter. At Folkestone they contain layers of calcareous matter and chert, and at Hythe, in the neighbourhood, as also at Maidstone and other parts of Kent, the limestone called Kentish Rag is intercalated. This somewhat clayey and calcareous stone forms strata two feet thick, alternating with quartzose sand. The total thickness of these Folkestone and Hythe beds is less than 300 feet, and they are seen to rest immediately on a grey clay, to which we shall presently allude as the Atherfield clay. Among the fossils of the Folkestone and Hythe beds we may mention Nautilus plicatus (Figure 277), Ancyloceras (Scaphites) gigas (Figure 278), which has been aptly described as an Ammonite more or less uncoiled; Trigonia caudata (Figure 280), Gervillia anceps (Figure 279), a bivalve genus allied to Avicula, and Terebratula sella (Figure 281). In ferruginous beds of the same age in Wiltshire is found a remarkable shell called Diceras Lonsdalii (Figure 282), which abounds in the Upper and Middle Neocomian of Southern Europe. This genus is closely allied to Chama, and the cast of the interior has been compared to the horns of a goat.