imbricatus; T. 272. fig. 3.

Irregular Univalves.

Serpula. This is a rare fossil in the lias: but I possess a specimen, changed

into pyrites, adhering to a belemnite.

Gryphæa incurva;-Sowerb. Tab. 112. Plagiostoma gigantea; T. 77.

Bivalves.

This family is very rare in the lias formation: the specimen represented in Pl. IV. fig. 5, is from the lias marl. I have seen also another species, but the specimens are not sufficiently distinct to be accurately classed.

* I have ventured to class this specimen as an Orthocera, as it possesses more of the character of that genus than of the Belemnite, the external shell not exhibiting the radiating fracture of the latter; and I have given it a specific name from its great length in proportion to the diameter. Mrs. White, to whom I am indebted for the specimen, informs me that it was originally considerably longer than at present.

↑ Besides the shells mentioned in the preceding list, numerous casts occur, which evidently belong to genera distinct from those above enumerated.

Pentacrinites Briareus.

subangularis.

CRINOIDEA.

Pentacrinites basaltiformis.

CORALS.

I have observed casts of this class in the lias of Lyme.

VEGETABLE REMAINS.

Knotted uncarbonized fossil wood, sometimes traversed by veins of calcareous spar, or sulphate of barytes;-represented in Pl. IV. fig. 6.

Lignite, generally flat-(described in Geol. Trans. second series, vol. i. p. 45.). Plants resembling Ferns; (Geol. Trans. second series, vol. i. Pl. VII. figs. 2. and 3.).

Part of another plant; represented in Pl. IV. fig. 7. of this volume.

Septaria are not uncommon in the lias marls: they frequently contain ammonites in their centre, but are sometimes entirely without organic remains.

Crystallized minerals are rare in this formation; iron pyrites, selenite, calcareous spar, and two or three varieties of sulphate of barytes, nearly completing the list. The pyrites frequently occurs in forms resembling those of mushrooms.

V. The following list of the beds between the white lias at Culverhole Point, and Axmouth Point, although not relating to the immediate object of the present paper, may be interesting, as it illustrates the upper part of the extensive new red-sandstone formation of Devonshire.

Section of the upper part of the NEW RED-SANDSTONE, near Axmouth Point.

* This light-coloured bed, and three or four other beds close to it, effervesce in different degrees

with acids, and might be termed very earthy limestone.

The total thickness of the red marl beds exposed between Culverhole and Axmouth Points may be about one hundred and twenty feet; the section exhibiting a few small faults, and a considerable curvature of the strata. After numerous alternations of blueish-green and red marl, the latter colour gradually becomes predominant, with a few occasional patches of green. The blueish-green patches, in the lower part of the section above given, afford traces of gypsum.

* At Branscombe, where a deeper part of the red marl section is exposed, gypsum is much more abundant; and mountain leather, or mountain paper, sometimes containing small crystals of celestine, occurs along with it at that place.

III.-Observations on the Strata at Hastings, in Sussex.

BY THOMAS WEBSTER, Esq., SECRETARY TO THE GEOLOGICAL SOCIETY.

[Read June 4th 1824.]

THE sea-cliffs on each side of the town of Hastings exhibit a section of the beds which lie below the clay of the wealds of Kent, Surrey, and Sussex, and furnish a key to understanding the structure of the high country which is surrounded by this clay and has hitherto been but imperfectly explored. In the present communication, I propose to give some account of the line of coast extending from the White Rock on the west of Hastings to Cliff End near to Winchelsea on the east.

Along this extent (Pl. V.) several valleys of denudation occur, which have separated the cliff into different portions. One of these valleys divides the White Rock from the West Cliff on which are the ruins of the ancient castle; in another, which divides the East from the West Cliff, the town of Hastings is built. In the middle of East Cliff is the romantic valley where the stream called Eaglesbourne forms the well-known fish-ponds; and to the east of East Cliff, and between it and Fairlee Cliff, is the place called the Govers. At Cliff End the cliff terminates, and gives place to the valley that goes up to Win

chelsea.

When we view this coast from the sea, we may perceive that the beds of rock form a vast, but irregular, arch, dipping at each end under the Weald clay, and rising in the middle to the greatest height in the neighbourhood of Hastings, where they may be advantageously studied.

In endeavouring to subdivide this mass of strata, a remarkable want of continuity and regularity may be noticed, which renders their examination difficult. The distinguishing features in the detail appear to be, that in the upper part a hard grey-coloured calciferous sandstone abounds; the middle part consists mostly of a yellow soft friable sandstone; and the lower part is composed of beds of clay, shale, and ferruginous sandstone, with several layers of ironstone, and numerous fragments of carbonized vegetables.

The grey calciferous rock is that which, several years since, first drew my

attention to the mineralogical nature of these cliffs. Many large blocks of it, sometimes 10 or 12 feet long, lie on the shore in a very picturesque manner, (See Pl. VI, fig. 2, a, a,) and have evidently fallen from the top of the cliff: they are broken up for paving and mending the roads, for which purposes they prove an excellent material; by their colour they are easily distinguished from the common yellowish sandstone in which they are imbedded, and which often remains firmly attached to them even after they have fallen.

These blocks of grey calciferous stone frequently have their upper and under surfaces distinctly mamillated, or formed of portions of spherical or spheroidal figures. It has been supposed by some who have noticed these fallen masses, that they have been worn into these forms by the action of the sea but this is evidently not the case; since they are of the same shape while still lying in the sandstone cliff in places where the sea could not have reached them, the mamillary masses existing before the blocks were detached from the yellow sandstone. Fig. 1. (Plate VI.) represents a portion of this rock viewed looking towards the sea; and at b, b, b, b, are seen the above-mentioned blocks in their places.

The sea does indeed frequently wear the surfaces of the blocks (and many of them are seen so worn), but in a very different manner. By the friction of the pebbles put in motion by the breakers, a number of hollows or concavities are worked out, intersecting each other, and separated by sharp ridges. These, (see c, fig. 2, Plate VI,) somewhat resemble casts taken from the mamillated surfaces; but in the rocks worn by the pebbles there are angular projecting ridges; in the others, there are angular depressions. This mamillary appearance is too regular and constant to be owing to accident, and can be attributed only to one of the varieties of crystalline action. The rock, when fresh broken, has a peculiar glistening lustre, which reminded me of the fracture of the crystallized sandstone of Fontainbleau, (the chaux carbonatée quartzifère of Haüy). Like that substance, the mamillated rock of Hastings is a sandstone having a small quantity of carbonate of lime, which however, involving the sand, has been sufficient to occasion the concretionary structure. It is however remarkable, that the stone is composed of thin layers of sand parallel to the bases of the mamillary projections; from which it would seem, that those masses had at first been sand, and that the calcareous matter which obeyed the crystalline influence had been introduced, or at least diffused through it, subsequently.

From the size of the masses in the cliff, they often, at first sight, resemble beds alternating with the sandstone; and it is only by a close examination that their want of continuity and the very irregular nature of their distribution ap