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WEALDEN FORMATION.

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sedimentary deposits, in the formation of which organised beings have played so prominent and important a part.”*

§ 17. WEALDEN FORMATION (ante, p. 192).-In regard to the stratigraphical phenomena of the Wealden of the Isle of Wight, no new feature has appeared in the cliffs of Sandown Bay, or in the bays to the west of Atherfield, requiring notice, except the occurrence of a stratum of soft sandstone between Atherfield and Brixton Bays, enclosing a thin layer of ironstone almost wholly made up of casts of a small species of paludina, and of one or two species of cyclas and unio. This deposit closely resembles the ferruginous sandstone with similar shells, mentioned in my "Geology of the South-east of England," as occurring at Groombridge in Sussex, and at Langton Green, near Tunbridge Wells; it may possibly hereafter assist in determining the chronological position which the Isle of Wight series should occupy in the Wealden formation.

The Wealden cliffs on the east and west of the Undercliff of the southern coast, have yielded but few additions to the flora of the country of the iguanodon; but the reptilian remains procured from these localities since my former notice equal, if not surpass, in number and interest all that I have previously collected, Through the liberality of Miss Fenwick, of Brook, Capt. Blackwood, R.N., Mr. Beckles, Sir R. Murchison, and other friends, I have obtained a most instructive series of vertebræ, and other bones, not only of the iguanodon, cetiosaurus, streptospondylus, goniopholis, &c., but of equally gigantic, and hitherto unknown or undescribed saurians. Many specimens were procured with much labour from the cliffs, when first exposed by a recent slip of the strata, and were thus preserved from that destruction of their processes and articulating surfaces, which takes place from exposure on the sea-shore: I have, consequently, succeeded in developing

* Dr. Fownes, on the "Presence of Phosphoric Acid in Rocks.”

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LIGN. 42-FIR-CONES, FROM THE WEALDEN, ISLE OF WIGHT.-Nat. size. (Abietites Dunkeri, mihi.)

Fig. 1.-A waterworn specimen, exposing the receptacles of the seeds. la.-Vertical section of the same, showing the axis, scales, and seeds. 2.-Partially abraded, so as to display many seeds in their cells.

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Figs. 3 and 4.-Longitudinal sections of two seeds, showing the dark carbonaceous pericarp, the substance of the seed transmuted into pyrites, and a central cavity lined with spar; the figures are

enlarged.

5.-Portion of a cone in which the expansions of the scales, more or less mutilated, remain, and conceal the cells and seeds.

6. An example in which the scales have been so much worn away by attrition, that the cells, with some seeds in situ, are beautifully exhibited. All the specimens are somewhat compressed.

several enormous vertebræ in a more entire state than any before obtained. I subjoin a cursory notice of a few of the most interesting Wealden fossils that have been recently collected.

§ 18. FIR-CONES, FROM THE WEALDEN.

When the

former edition of this work was published, a fragment of a fir-cone from Sandown Bay, and two or three rolled specimens, apparently of the same species, from Brook, were the only remains of the fruits or seed-vessels of the Wealden coniferous trees, that had come under my notice. Within the last few months I have obtained a considerable number of cones from the pyrites, collected by the fishermen from the cliffs to sell for "copperas ;" and although I have seen no perfect example, yet in some specimens the structure of the cone, and the position of the seeds, are sufficiently displayed to afford a tolerably correct idea of the form and organisation of the original. In the annexed figures (ligns. 42, and 43,) I have delineated five specimens, all of which are more or less waterworn, but exhibit in their different states of abrasion, the scales, the disposition and spiral arrangement of the receptacles, and the seeds themselves. In lign. 43, is represented a more perfect example of the appearance of the cone with the scales, and their foliated expansions, which, though mutilated, are not worn away so as to expose the receptacles. The vertical section, fig. 1 a, shows the relative size of the axis and the investing scales.

These fossils are always found in a metallic state, the

U

constituent substance consisting of pyrites and carbonaceous matter. The seeds are often exquisitely mineralised; the membranous pericarp is generally carbon; the solid part

of the seed is converted into

pyrites, and where a cavity has been left by the decomposition of the embryo, it is lined with cal careous spar.

These cones are of an elongated cylindrical form, the proportion of the length to the circumference being as 4 to 1; the base is somewhat tapering, the summit rounded. The largest specimen I have met with is 9 inches in length. The scales are broad, slightly convex without, and concave within, thin and somewhat rounded at the points, and thicker near the axis, and, as in the cone of Abies oblonga of the greensand strata,* seem to have consisted of a woody central plate, deeply covered with a woolly tissue, which gave way to the pressure of the seeds. The scales appear to have had a slightly elevated midrib externally, but the perfect form and outline of the scale cannot be determined from any of the numerous specimens in my possession.

Nothwithstanding the abundance of vegetable remains in the Wealden deposits of Germany, it does not appear that any * "British Fossil Flora," p. 137.

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LIGN. 43.-FIR-CONE, FROM BROOK BAY.- Nat. size.

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fir-cones have been observed, although the coal of the extensive Hanoverian basin is chiefly composed of the foliage and stems of firs or pines, some of the beds being nothing more than a bituminised mass of compressed needle-like leaves of coniferæ. The most abundant

species (Abietites Linkii*) has a small acicular leaf, with a slightly elevated midrib, from one to two inches long, but the foliage and small twigs bearing the cicatrices of the petioles are the only recognisable parts of the tree. I have seen in the strata at Brook Bay traces of similar leaves and

stems.

These cones unquestionably belong to the coniferous trees composing the drifted forest or raft at Brook, (see pp. 204-208,) and we have, therefore, at length acquired sufficient knowledge of the form and structure of the wood, trunk, branches, foilage, and fruit, to enable the accomplished botanist to reconstruct and delineate the pine-forests that must have extended over vast tracts of

* Dr. Dunker's "Monograph on the Wealden of North Germany," tab. ix. fig. 11 ("Monographie der Norddeutschen Wealdenbildung. Braunschweig, 1846 "), which is thus described :-"ABIETITES (Abies) LINKII (Römer), rather thick, linear, leathery leaves, narrow at the base, and truncated at the point, traversed by a median nerve, which gradually becomes less distinct upwards; on the under side of the leaf the midrib is distinct only towards the base. The upper surface is usually from the base upwards covered with very fine transverse folds or wrinkles, as if from the shrinking and corrugation of the parenchyma. Most of the leaves are of a dark brown colour, and are glossy, transparent, and flexible, being but imperfectly carbonised. They are found associated with cypress twigs, pterophyllum Lyellianum, and remains of other plants, in the slaty and foliated coal at Duingen, as well as at Diester and Osterwalde, and are compressed together in such extraordinary quantities, that those beds of coal are almost exclusively formed of them. It is not rare to find small branches distinctly marked with the scars left by the removal of the petioles, M. Römer has observed the oval ripened scales of fir-cones.""Mon. Nord. Weald." pp. 18, 19.

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