CHAPTER III. PART IV. GEOLOGY OF THE SOUTH-EAST OF ENGLAND. "Ah, happy hills! ah, pleasing shade! Ah, fields beloved in vain! Where once my careless childhood stray'd, I feel the gales that from ye blow A momentary bliss bestow."-GRAY. QUARRY IN TILGATE FOREST-STRATA OF TILGATE FOREST-CHARACTER OF THE ORGANIC REMAINS-DISCOVERY OF THE FLUVIATILE ORIGIN OF THE STRATA-GEOLOGICAL STRUCTURE OF THE SOUTH-EAST OF ENGLAND-DRIFT OR DILUVIUM TERTIARY OR EOCENE STRATA CHALK FORMATION— WEALDEN FORMATION-ORDER OF SUPERPOSITION OF THE STRATA-PHYSICAL STRUCTURE OF THE COUNTRY SECTION FROM LONDON TO THE SOUTHERN COAST-LONDON AND BRIGHTON RAILWAY SECTION-JOURNEY BY COACH FROM BRIGHTON TO LONDON-GEOLOGICAL MUTATIONS-FAUNA AND FLORA OF THE WEALDEN-SUMMARY. QUARRY IN TILGATE FOREST.-From the motley crowds of strangers attracted to our overteeming metropolis by the "CRYSTAL PALACE and its wonders," thronging in countless numbers every place of public resort-the Gallery of Organic Remains of the British Museum not excepted,I would transport the Courteous Reader for a brief space, and conduct him to the verdant hills and refreshing glades of my native county, and forgetting awhile "the noise, the hum, the din of men," visit the quarries, and examine the rocks and strata, whence the fossil remains of the colossal reptiles that will next engage our attention were exhumed. In the good old times, when a well-appointed four-horse coach conveyed the traveller from Brighton to London in six or seven hours, the first resting stage for the passengers after leaving the Queen of Watering-places on a summer's morning, was the neat little town of Cuckfield in Sussex; whose single street straggles up the southern slope of a steep acclivity, formed by the anticlinal ridge of Wealden grit, which emerges from beneath the clays and sands of the adjacent valley of Cuckfield Park, near the seat of my friend, Warden Sergison, Esq. On the summit of this ridge is "Whiteman's Green," and there, some thirty years since, was an extensive quarry, that had been occasionally worked for a quarter of a century, and was then in unwonted activity; the calciferous grit,—a hard calcareous sandstone formed by an infiltration of crystalline carbonate of lime into beds of sand,-which had always been in request for various economical purposes, having suddenly acquired increased value from the great demand for road materials, occasioned by the competition between the various boards of trustees, in consequence of the rapidly augmenting number of coaches and passengers, which the rising prosperity of Brighton had called forth. From that quarry, long since filled up, and the area covered by pasturage and gardens, I collected the first and most interesting of the fossil remains of the Iguanodon, Hylæosaurus, Pelorosaurus, and other stupendons creatures whose existence was previously unknown and unsuspected. The sketch, (Lign. 45,) represents the section exposed on one side of the quarry in 1820. The spire of Cuckfield Church is seen in the middle ground; the hills in the extreme distance are part of the range of South Downs to the west of Ditchling Beacon, an eminence of the chalk that rises to the height of 856 feet. 1. The lowermost bed, forming the floor of the quarry, is a stiff blue clay, in which bones and freshwater shells are occasionally met with. 2. The succeeding strata are composed of the fine calciferous grit or Tilgate-stone, which was extensively used as a road material, and occasionally for walls and buildings; but, owing to its extreme hardness, the difficulty of reducing it to blocks of convenient size, together with the adaptability of the softer sandstone for the purpose, was but seldom employed in architecture. In some of the beds pebbles of quartz and jasper are so thickly interspersed, that the rock acquires the character of a conglomerate. 3. Above the Tilgate-grit are strata of fawn-coloured sands and sandstones, having the same lithological features as the cliffs at Hastings, and the rocks at Tunbridge Wells, Uckfield, &c. The upper part of these sandstones are in the state of laminated friable shales. 4. A thick bed of diluvial loam caps the whole, and forms the immediate subsoil of the surrounding country.' STRATA OF TILGATE FOREST.-The quarry above described exhibits the usual character of the strata exposed in natural sections, and in the various stone-pits, and other artificial openings, in the surrounding country, and which extend, with but little variation, over the area of Tilgate and St. Leonard's Forests, to Horsham on the west, and along the Forest Ridge on the east. As a general term for these deposits was required for the convenience of description, I adopted that of "Strata of Tilgate Forest," on account of the proximity of the locality in which the saurian remains were first observed, to the district which, though now cultivated, and smiling with gardens and villas, still retains a name handed down from the earlier centuries, when it formed an integral part of the Roman Sylva Anderida, and in later times of the Saxon forest of Andreadswald.2 It was in this quarry, to which my attention was accidentally drawn by observing a fragment of bone in a block of stone by the road side, that I first obtained teeth, scales, and bones of reptiles and fishes, and fresh-water mollusks and crustaceans, and remains of terrestrial plants of a tropical character; a discovery which has invested this locality with a high degree of geological interest, since it was the first step in those researches which ultimately revealed the true nature and origin of the strata composing what is now termed the 1 Consult the "Fossils of Tilgate Forest," (published in 1827,) 1 vol., royal 4to. for details of the stratification, and figures of the principal fossils then obtained from the quarry: or, "Geology of the South-East of England," 1 vol. 8vo. 1833. 2 See Horsfield's "History of the County of Sussex." Wealden formation; a name happily suggested by my friend J. P. Martin, Esq. of Pulborough, to designate this remarkable series of fluviatile deposits. PECULIAR CHARACTER OF THE ORGANIC REMAINS. The most novel and extraordinary fossil remains which I obtained from the locality above described, and from other quarries around Horsham, Bolney, and Crawley, to which my researches extended, were the fragments of enormous mammalian-like bones, and the stems, branches, and foliage of terrestrial vegetables, and fluviatile mollusks; the univalves resembling the river-snails, or paludinæ, and the bivalves the fresh-water mussels or uniones. These phenomena were quite unexpected; for although, so far back as Woodward's time, the shells composing the limestones commonly known as the Sussex and Petworth marbles were supposed to be river-shells, yet that opinion had long been given up, and the whole series of strata forming the tract of country between the North and South Downs were regarded as unequivocally marine, and an integral part of the Cretaceous formation; the sands and sandstones being grouped together under the name of the Iron Sand; and several species of ammonites, nautili, and other deep-sea shells, were figured and described by Mr. Sowerby, and other eminent naturalists of that period, (1820,) as characteristic fossils of that group of deposits. In that excellent work, Messrs. Conybeare and Phillips' "Outlines of the Geology of England and Wales," published in 1822, there is an admirable review of the geological relation of the "Iron Sands" below the chalk, according to the state of geological knowledge at that time, and which will be found in accordance with the account above given.1 DISCOVERY OF THE FLUVIATILE ORIGIN OF THE STRATA. For many years previously to my discovery of organic remains in the Wealden strata, I had diligently collected the fossils from the chalk, chalk-marl, galt, &c. around Lewes, where I then resided, and had acquired a tolerably extensive suite of the usual teeth, shells, corals, and other zoophytes of the 1 "Outlines of the Geology of England and Wales, by the Rev. W. D. Conybeare, and William Phillips, 1822," pp. 136-140. This volume appeared about three months before my first work on the Geology of Sussex, "The Fossils of the South Downs." Cretaceous formation; these were arranged in separate drawers according to their respective localities. In the course of a few months after my first visit to the quarry at Cuckfield, I had obtained from the Weald, specimens of the rocks and organic remains in sufficient number to fill a cabinet of moderate size; and I soon became aware of the important difference between these fossils and the characteristic species from the chalk deposited in my other drawers: and by degrees the fluviatile origin of the strata spread over the Wealds of the South-East of England suggested itself to my mind. The absence of ammonites, echinites, corals, terebratulæ, and other marine organisms, which constituted so large a proportion of my cretaceous collection, was the first striking anomaly that forced itself on my attention; and many a long and weary journey have I undertaken, to examine the materials thrown up from a newly-made well, or the section exposed by recent cuttings on the road-side, in the hope of obtaining data by which the problem might be solved; but it was many years ere the validity of my arguments received general assent. By reference to the various works on the Geology of the South-East of England' the reader interested in the history of the Wealden, may form some idea of the difficulties encountered, the mass of evidence required, and the prejudices of long cherished opinions to be overcome, and the able assistance and warm encouragement I received from my distinguished friend Sir Charles Lyell, and subsequently from other eminent British geologists, ere the fluviatile origin of the strata composing the Wealden was established. As a considerable number of the organic remains that will come under our notice in Room V. of the Gallery of the British Museum, were obtained from the cretaceous and tertiary deposits of the South-East of England, it will be convenient to review the geological phenomena of the whole district in the present section of this work, which is in a great measure restricted to the consideration of the characters 1 See "Wonders of Geology," 6th edit. lecture iv. p. 366, for a condensed exposition of the geology and fossil remains of the Wealds of Sussex, Kent, and Surrey. For the history of the character and relations of the strata below the chalk, consult the able Memoirs by Dr. Fitton in the "Geological Transactions." |