Excursion to Folkestone. 18th June, 1870 - Geologists' Association excursion

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From: A record of excursions made between 1860 and 1890. Edited by Thomas Vincent Holmes , F.G.S. and C. Davies Sherborn, F.G.S. London: Edward Stanford [For the Geologists’ Association], 1891. Source: Cornell University copy on the Internet Archive (Public domain work)

Note: Folkestone, Sandgate and Hythe. [At the conclusion of the Easter Excursion of 1885 the members of the Association who were present returned to London from Sandwich. Deal, however, remains unvisited, and though Dover was the scene of an excursion on August loth, 1863, no record appears to exist of the sections then seen. But Folkestone seems to have been the very first place ever visited by the Association, the date of this first Excursion having been April 9th, 1860. In Proc., vol. i., p. 47, it is stated that the party "proceeded at once to the shore, and spent several hours in examining the Chalk, Greensand, and Gault, as exhibited in East Wear Bay, the Warren,. and Copt Point, and procured several specimens of the characteristic fossils." The succeeding excursions to Hythe and Folkestone took place in 1864, 1865, and 1866, during the period when no Proceedings were issued; their details consequently remain unrecorded. Excursions to Folkestone and the neighbourhood are, however, chronicled in the Proceedings, one in 1870, another in 1876, and a third in 1883. As the account of the last of these is best adapted to serve as an introduction to this district it is here given first.]

Excursion to Folkestone. 18th June, 1870

On arriving at the harbour pier a survey was taken of the chief points of interest along the coast to right and left of Folkestone. The fine Chalk cliffs forming the northern boundary of East Wear Bay, rising at Folkestone Hill to a height of 566 feet; the outcrop of the soft clay beds of the Gault, and the consequent sudden recedence of the coast; the rise of the sands and stone-beds of the Neocomian strata from beneath Copt Point, and their continuance to and west of the town of Folkestone, were all matters of remark; while the former existence and position of a gravel-bed containing the remains of extinct mammalia—Elephas, Rhinoceros, etc.—on the high ground above the harbour, were noted.

The strata first examined in detail were some dark-greenish sub-argillaceous sands, known as the Sandgate Beds, which rise on the shore at a short distance west of Folkestone. The low under-cliff which skirts the shore from Folkestone nearly to Hythe was shown to owe its origin to the presence of these beds, which, from their retention of water and slight coherency of structure, have caused the frequent subsidence of the beds above. These greenish beds, it was observed, contain sulphur, iron-pyrites in minute grains, and a large proportion of silicate of iron. Unlike the sands above, they do not effervesce in acid.

The sands and silicious sandstones of the Folkestone Beds above were next examined, and proved to be highly interesting. Sandy conglomerates, containing rounded fragments of quartz, white or grey, often stained to a greenish colour; fragments of quartzite, jasper, and flinty slate, mingled with small phosphatic nodules and casts of shells, were seen to alternate with soft marly beds, containing an abundance of fossils. The stone beds at a higher level, ranging upwards almost to the Gault, were shown by Prof. Morris to consist, in great measure, of the remains of sponges. This was best seen beneath the cliffs to the east of Folkestone; the huge slabs of stone just above tide-mark being in many places literally made up of sponges, exhibiting in the weathered cavities left by the decomposition of the more ramose varieties a perfect network of silicious spiculm. Sections showing the passage of the Neocomian sands into the Gault were next examined, the chief points observed being the gradual increase of argillaceous matter in the sands when approaching the Gault; the occurrence of a band of phosphatic nodules, associated with Ammonites mammillaris, about three feet beneath the Gault; and the abundance of pyritized coniferous wood contained in the nodular phosphatic bed at the base of the Gault itself. Evidence of the constant slipping forward of the Gault over its own basement bed was in places very apparent.

[The Dungeness corner of Kent was visited on June 14th, 1886 (Whit Monday). The party slept at Hastings, and the next day's excursion was to Rye, Camber Castle, and Winchelsea. A full report will be found in the Proc., vol. ix. p. 544.]

References

Maps

Ordnance Survey. Geological. Sheets 3. 8s. 6d. 4. 5s.

New Ordnance Survey. Sheets 289, 290, 305, 306, 321. 1s. each,

Books

W. H. Fitton, On the Strata below the Chalk. Trans. Geol. Soc., ser. 2, vol. iv. pp. 105-131. 1836.

F. Drew, The Geology of the Country between Folkestone and Rye (Mem. Geol. Survey). 1864. 15.

C. E. De Rance, On the Albian, or Gault, of Folkestone. Geol. Mag., vol. v. pp. 141-148. 1868.

F. G. H. Price,. On the Gault of Folkestone. Quart. Journ. Geol. Soc., vol. xxx. pp. 342-368. 1874.

F. G. H. Price, On the Lower Greensand and Gault of Folkestone. Proc. Geol. Assoc., vol. iv. (No. 2), pp. 135-150. 1874.

F. G. H. Price, The Gault. 1879. 3s. 6d.

W. Topley, The Geology of the Weald. (Mem. Geol. Survey.) 1875.

H. B. Woodward, The Geology of England and Wales, 8vo, London, ed. 2, 1887, pp. 368-372.