§ 3. Such is the order in which the strata around Lewes have been deposited; but to illustrate more fully the manner in which the different beds emerge from beneath each other, a plan of the superposition of the strata is given in Plate xxvii. It is scarcely necessary to remark, that the view of the town, introduced in the back-ground, is merely intended to give a picturesque effect to the sketch. The following description will serve to render it intelligible. 1. Alluvial and Diluvial beds, the debris of the more ancient formations. 2. Plastic Clay Formation. 3. Upper, or Flinty Chalk. 4. Lower Chalk. 5. Grey Chalk Marl. 6. Blue Chalk Marl. 7. Green or Chlorite Sand. 8. Weald Clay. 9. Iron Sand. 10. Tilgate Beds. § 4. The general inclination or bearing of the strata is towards the south-east, a line drawn from the coast towards the interior of the country, or, in other words, from Newhaven to Wytch Cross, would therefore pass over the bassetting' edges of the strata, in the order of succession above mentioned. Hence a corresponding difference is observable in the physical appearance of the country, and in the nature of the soil and its vegetable productions; the surface being diversified by hill and dale, and valleys and rivulets intervening, wherever the different formations form a line of junction. But proceeding in an opposite direction, or from the north-east to the west, no such change is observable; the traveller passes along the same series of strata, the surface of the country, consequently partakes of one undeviating character, and the vegetable productions present but little variety. He either travels over a chain of chalk hills covered with turf, where patches of heath and furze, with scarcely a tree or coppice, meet his eye; he perceives numerous flocks of sheep and their attendant shepherds, with here and there a hut or cottage in a sheltered glen; or he skirts along the foot of the Downs, and traverses a rich and fertile tract of marl and clay, checkered with numerous farms, in the highest state of cultivation;—or proceeding in a line parallel with, but more northward of the Downs, he observes a district abounding in forests of oak, and intersected by roads scarcely passable except in the height of summer; here he finds the peasantry occupied in felling the woods, or in digging up limestone for architectural purposes;-or, lastly, if he crosses the interior of the county, still keeping in a direction parallel with the northern escarpment of the chalk hills, he finds a sandy, and in many places a sterile tract of country every where surrounding him, bounded on the north by a ridge of sand hills, crested with forests, and abounding in picturesque 1 When a stratum emerges from beneath another, it is said to basset, or crop out. The author may here be permitted to observe, that he has endeavoured as much as possible, to avoid the employment of technical terms; at the same time it should | be remembered, that however delightful or inviting any science may be, a knowledge of it cannot be obtained, without previously learning its terms, for every science, and indeed every trade, “has a language of its own. scenery: so much are the geographical features of a country, and even the occupations of its inhabitants, influenced by the character and distribution of the strata. § 5. Although the alluvial deposits are the most recent, and stand the first in the series, yet for reasons too obvious to require notice, their consideration will be deferred to the concluding section, and we shall proceed at once to the Tertiary formations. TERTIARY FORMATIONS. § 6. PLASTIC CLAY.-The tertiary formations consist of various beds of sand, clay, marl, &c., which appear to have been deposited in hollows or basins of the chalk. Two of these concave areas have been discovered in England; one of which, from its including the Metropolis, has been named the London Basin; and the other, that of the Isle of Wight, from its characters being more fully developed in that island, than elsewhere; it is to the latter that the strata before us belong, as will appear from the annexed diagram. § 7. Castle Hill, the summit of which is composed of beds of the Plastic Clay, is situated on the western side of the mouth of the Ouse, about one mile from the town of Newhaven, and eight miles from Lewes. On its eastern brow, the remains of an ancient castrum or earth-work is still visible, which has evidently, at a former period, been of considerable extent, although now comprising scarcely more than five or six acres. The surface of the hill towards the sea, presents a broken and rugged aspect, and near the edge of the cliff, the strata are in so ruinous a state, and the fissures so extensive, as to render their approach dangerous, and difficult of access. From the decomposition and destruction of the strata, which is constantly taking place, it is only after recent falls of large masses, that an instructive section is exposed; that delineated in Tab. xxvii. was sketched a few years since, and serves to convey a tolerably correct idea, of the general characters, of this interesting series of deposits. The total thickness of the beds, exclusive of the chalk, does not exceed sixty or seventy feet; and they extend about one mile along the coast to the west of the signal house. SECTION OF CASTLE HILL, NEAR NEWHAVEN. § 8.-1. Gravel, composed of broken and rolled chalk flints: thickness, about ten feet. 2. Coarse argillaceous rock, chiefly composed of oyster shells, with a few spiral univalves. 3. Blue Clay, with numerous bivalve shells; cytherea, cyclades, and cyrene. 4. Blue Clay, containing immense quantities of spiral univalves; chiefly referable to two species of Cerithia. 5. Reddish Brown Marl, with impressions of leaves, some of which resemble the foliage of the platanus orientalis, and others that of the Nerium oleander. A specimen is represented Tab. xxix., fig. 16. 6. A seam of surturbrand, or impure coal. 7. Blue Clay, abounding in selenite, and including a layer of marl, of a sulphur yellow colour. 8. Sand of various shades of yellow, ash colour, and green. 9. Breccia or Puddingstone, composed of green sand and rolled flints, the latter covered with an ochraceous yellow crust. 10. Ochraceous Clay, with tabular and tuberose masses of hydrate, and subsulphate of alumine. 11. Chalk, of which the lower part of the cliff is composed. § 9. From the number and variety of the mineral and fossil productions of the strata above described, Castle Hill is peculiarly interesting to the collector; the bivalves, univalves, crystals of gypsum, &c. may be obtained in abundance on the summit of the cliffs; but the alumine from its being situated in the lowermost of the tertiary beds, and above the chalk, which rises to an elevation of nearly sixty feet, can only be procured on the sea shore, after recent falls. § 10. At Chimting Castle, about half a mile to the east of Seaford, an insulated portion of the breccia (No. 9.) and sand, remains incumbent upon the chalk; and the summits of the Downs between Seaford and Newhaven, are capped with patches of fawn-coloured and greenish sand, containing rolled blocks of chalk, and pebbles. In a chalk-pit near Piddinghoe, as well as in many other places, traces of similar deposits are visible. § 11. On the opposite coast of France, near Dieppe, strata of a similar character, appear in the same relative position. § 12. DRUID SANDSTONE.-Immense boulders of siliceous sandstone, composed of granular quartz, and occasionally enclosing chalk flints, and other extraneous substances, lie scattered over the surface of the Downs, and in the valleys in this neighbourhood. § 13. Some remarkable groups of these boulders occur near Falmer, Brighton, Alciston, &c., but by far the largest that we have noticed, are situated in Gold-stone bottom, in the parish of Hove, near Brighton. This sandstone is perfectly analogous to that of which Stonehenge, and other Druidical monuments are composed, a circumstance that has given rise to its present appellation. There can be no doubt that it originally formed a regular bed in the tertiary formations, but the precise situation it held in the British strata, has not been determined. It is evidently identical with the calcaire silicieux of the French geologists, which is said to be above the plastic clay. § 14. Our limits will not admit of a more extended notice of these beds, and we must refer the reader for further particulars to the Geology of Sussex, p. 256. We may, however, remark that the nature of the organic remains so abundantly distributed in these beds, as well as the physical characters of the strata, are so essentially distinct from those of the chalk on which they repose, that no doubt can arise of their having been deposited at a subsequent period, and under very different circumstances. CHALK FORMATION. § 15. UPPER AND LOWER CHALK.-The strata comprehended in this section, form by far the most striking features in the Gcology of the environs of Lewes, and constitute those smooth mountain masses, so well known by the name of South Downs. The geographical description of the country inserted in a former part of this volume, will sufficiently point out the range and extent of these deposits. Varying in altitude from three hundred to upwards of eight hundred feet, this chain of chalk hills extends from Beachy Head to Brighton, and from thence through the centre of western Sussex into Hampshire. On the north it presents a precipitous escarpment, but on the south it descends with a gentle slope, and towards the south-west is lost beneath the strata of the Isle of Wight Basin; while on the north-east, it forms a line of cliffs of considerable extent. The South Downs are intersected by four transverse valleys, through which the Arun, the Adur, the Ouse, and the Cuckmere, flow from the interior of the county, into the British Channel. The general inclination of the chalk strata, is towards the south-east; in a few instances, however, the influence of local causes has occasioned some exceptions. A remarkable instance of this kind occurs at Southerham, near Lewes; where the beds of the lower chalk are highly inclined, and dip beneath those of the upper, which preserve a nearly horizontal direction. § 16. The summits of the hills are covered with layers of loose flints, which lie immediately beneath the turf, and afford excellent materials for repairing the roads'. The chalk, which is a carbonate of lime, is used in large quantities as a manure, after being deprived of its carbonic acid by the action of fire. It was formerly employed in architecture, and the Town walls, and those of the Priory, which have stood nearly eight centuries, prove how well calculated it is for such purposes, when the surface is protected from the action of the atmosphere. The upper beds of the chalk abound in horizontal layers of siliceous nodules or flints, but the inferior strata are destitute of them; from this circumstance the chalk has been divided by geologists into the upper or flinty chalk, and the lower chalk. The subdivisions are also characterised by the nature of their fossil remains. 1 A considerable number of the peasantry are employed in | digging up and breaking the flints for that purpose, but the slovenly manner in which they replace the turf cannot be too strongly reprobated, and onght to attract the attention of those | who superintend their labours. Wherever the pickaxe and spade have been employed, a rugged and uneven surface remains for years, destroying the beautifully smooth appearance, for which the Sussex Downs were formerly so celebrated. |