View source for Excursion to Sevenoaks and Tonbridge, Saturday, June 14th, 1879. (Third of the Weald Series) - Geologists' Association excursion

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Director—J. Logan Lobley, F.G.S. (Report by W. Fawcett, B.Sc.) (Proc. Vol. vi. p. 202).

[Note: Sevenoaks was also visited by the Association in 1864 and 1866. In Proc. vol. i., p. 390, about a dozen lines are given by Caleb Evans to the details of the excursion of 1864, followed by a paper on the Geology of the district The excursion was especially undertaken to inspect the Geology of the extensive railway-works carried on by the South-Eastern Railway at that time, and the paper may be consulted with advantage. The excursion of 1866 took place while no Proceedings were published.]

Members left the train at Dunton Green to inspect the excavations in the extensive Brick-yards of Mr. W. J. Hooker, who courteously gave every facility for the observation of the sections and the collection of fossils. These excavations well show the Gault; it extends E. and W. for many miles along the base of the escarpment of the North Downs, forming the beautiful Vale of Westerham. Both the Gault and the Pleistocene Brick-earths which cover the Gault in places along the valley, afford here materials for bricks and tiles.

After crossing the alluvium of the Darent Valley, and the stream itself, the Folkestone Beds of the Lower Greensand were found exposed in a field near Riverhead, through which village the party then proceeded to the Tub's Hill (Sevenoaks) Station. Between the station and the tunnel there is a fine section, about Soft. high, showing the Hythe Beds of the Lower Greensand, and yielding abundance of ''Gryphaa sinuata''. F. Drew, in Topley, (Geology of the Weald, p. 116), gives the following description of the beds on the coast of Kent :"The Hythe beds are interstratifications in about equal proportions of limestone and sand. The former is close in texture, has a grayish blue colour, and contains fine grains of quartz; the latter is for the most part drab-coloured, impure, rather clayey, and somewhat calcareous; the stone goes by the name of 'rag,' while the intermediate sandy beds are called 'hassock.'" At Sevenoaks the distinction is not so great; the hassock is harder, is in a larger proportion than the rag, and both are used for building. The Sandgate Beds, intermediate between the Folkestone and Hythe Beds, are here wanting, whereas at Folkestone all three are developed. A good example of a fault, and a remarkable anticlinal, were noted near the entrance to the tunnel. The Folkestone Beds cover the Hythe Beds, and form the high ground on which the town of Sevenoaks stands. The junction was seen as the party ascended from the railway cutting and made their way to Sevenoaks. A brief visit was paid to Knole Park, in which the beautiful country formed by the Lower Greensand of Kent is well shown.

Proceeding along the road to River Hill, on the escarpment of the Lower Greensand, a fine view over the second of the great east and west valleys was obtained. At the bottom of the hill is the Atherfield Clay, then the broad expanse of Weald Clay, with the Medway meandering through it. The road through Hildenborough was taken, and after a brisk walk across the Weald Clay vale, rich with hop-gardens and orchards, Tonbridge was reached, standing close to the Alluvium of the Medway.

[[Category:Geologists' Association excursions]]