Excursion to Battle and Hastings. Easter Monday and Tuesday, April 10th and 11th, 1882 - Geologists' Association excursion

Directors: William Topley, F.R.S., and J. E. H. Peyton, F.G.S. (Report by W. Topley.) (Proc. Vol. vii. fi. 356.)

The chief geological interest of this excursion consisted in an examination of the lowest beds exposed in the Wealden Area. These, formerly known as Ashburnham Beds, but now classed as Purbeck, are exposed along a narrow line on the north and north-west. of Battle. The lowest beds of the Fairlight Cliffs were also formerly called Ashburnham Beds, it being supposed that these and the beds near Battle were on the same geological horizon. Of the correctness of this determination there have always been grave doubts, and it is now known to be erroneous.

The highlands of the Wealden Area in East Sussex are formed of sand and sandstone (Ashdown Sand) brought up along anticlinals and by faults. This Ashdown Sand is probably 500 feet thick. Its lower part is clayey, and it is underlaid (though generally with a faulted boundary) by the beds now known as Purbeck.

The cliffs of Fairlight, east of Hastings, expose a thickness of about 150 feet of sand and sandstone (Ashdown Sand); but below this there are 360 feet, with no base reached, of sand, sandstone, and mottled clay. These lower beds are now known as the Fairlight Clays; they represent the lower and more clayey part of the Ashdown Sand of inland areas. Without doubt they overlie the Purbeck Beds, which would probably be reached at a small depth only below the centre of the anticlinal at Fairlight.

The stratigraphical evidence for the succession as now adopted is, therefore, sufficiently strong. But the Sub-Wealden Boring has shown that the lowest beds of the inland area contain important beds of Gypsum, a mineral scarcely known in the Wealden Beds proper. Beneath them came the Portland Beds. Palmontologically, also, the revised reading is desirable, as estuarine shells frequently occur at various horizons in the Purbeck Beds, whilst the Wealden Beds of this area are characterized by fresh-water forms.

Monday

The party assembled at Battle Station.

After inspecting the ruins of Battle Abbey the members drove northwards to the most easterly exposure of the Purbeck Beds, in Archer Wood. Thence a short walk brought them to the tramway from the Sub-Wealden Gypsum works, up which a journey was made in waggons. Three hundred years ago Sussex was a busy centre of the iron trade; but the mineral manufactures gradually declined, and during the last 30 or 40 years these have been almost limited to lime-burning. The discovery of Gypsum, however, which is now being extensively worked, has once more placed Sussex in the list of mineral-producing counties.

The total thickness of the Sussex Purbecks is about 409 feet; 300 feet are exposed at various places; the lowest 100 feet or so are only known from the boring. Beds of limestone, once largely worked by means of pits, occur chiefly at two horizons, an upper one known as "The Greys" and a lower one called "The Blues." Below the Blues come other scattered bands of limestone, whilst lower still we have the shales with Gypsum. The Greys and the beds near them are usually very fossiliferous; the lower beds much less so.

The Sub-Wealden Boring was made during the year 1872-75, chiefly through the exertions of Mr. Henry Willett, of Brighton. A good selection of the cores, with illustrative sections, is placed in the Brighton Museum.

Prof. J. F. Blake suggests the following as a possible classification of the beds passed through in the boring :

	Thickness. feet	Depth from Surface, feet
Purbeck	180	180
Portlandian	60	240
Bolonian	660	900
Virgulian and Pterocian	430	1330
Astartian	30	1360
Supra-coralline	390	1750
Corallian	90	1840
Oxfordian	65	1905

Tuesday

This day was devoted to an examination of the cliffs east of Hastings. The cliffs are capped by Wadhurst Clay, near the base of which are bands of clay ironstone, and a shelly band of ironstone full of Cyrena. These beds were the chief source of the ore of the old Wealden furnaces.

The top bed of the Ashdown Sand is massive, and forms natural rocks round the valleys. It is hard externally when weathered but inside it is soft. St. Clement's Caves at Hastings are excavated in this bed. A bed of shale, 30 feet below the "top of the sands, makes a distinct feature in the cliff; it contains Endogenites erosa. Some interesting cases of extreme false-bedding were noticed. One of them, just east of Ecclesbourne, might be mistaken for evidence of local unconformity between the Ashdown Sand and Fairlight Clays. The characteristic mottled-clays of the Fairlight group appear in quantity near and east of Fairlight Glen.

A large groyne lately built east of Hastings intercepts the travel of shingle from west to east along the coast. The western end of the town has suffered much from the rapid removal of shingle and the wasting action of the sea.

[On Whit-Monday and Tuesday, 1886, there was an excursion to Dungeness, Rye and Hastings, the Directors being W. Topley, F.R.S., J. E. H. Peyton, and George Wilks. A report of it may be seen in the Proceedings (vol. ix. p. 544).

Maps

Ordnance Survey. Geological. Sheets 4, 5s.; 5, 8s. 6d.

New Ordnance Survey. Sheets 304, 305, 320, and 321, 1s. each.

Books

W. H. Fitton, On the Strata between the Chalk and the Oxford Oolite in the South-East of England. Trans. Geol. Soc. ser. 2, vol. iv. 1836.

W. Topley, The Geology of the Weald, 8vo, London (Geol. Surv.). 1875. 28s.

F. Drew and R. Etheridge, On the Geology of the Country between Folkestone and Rye, 8vo, London (Geol. Surv.). 1864.