# Transactions of the Geological Society, 1st series, vol. 2/On the Strata lying over the Chalk

By Thomas Webster, Member of the Geological Society.
INTRODUCTION.
AMONG the geological researches which have lately been made in various parts of the globe, none have been more interesting than those of M. M. Cuvier and Brongniart in the environs of Paris.
These naturalists have described a series of mineral strata differing in many respects from all that were formerly known, and particularly distinguished by their numerous and singular organic remains. The animals whose exuviæ had hitherto been more commonly noticed in regularly stratified rocks were the inhabitants of an ocean: but many of the Parisian fossils belonged to freshwater lakes and marshes, thus developing new and unsuspected agents in the forming of mineral beds.
The strata described by the French naturalists are deposited in a cavity in the chalk stratum which extends through a considerable part of the north of France. The bottom of this hollow is extremely irregular; and before it was covered by the materials now found in it, must have presented partial cavities and projections, the latter appearing as so many islands piercing through the other strata; and ​it is an important observation that there is no correspondence between the irregular form of the bottom and that of the present surface of the country.
Although the number of distinct beds or layers in this basin is very considerable, yet the authors of the memoir have reduced them to eleven principal classes.
* Chalk.
* Plastic clay.
* Coarse limestone and sandstone.
* Silicious limestone.
* Gypsum and marl, containing bones of animals, forming the lower freshwater formation.
* Marles of marine origin.
* Sand and sandstone without shells.
* The superior marine sandstone.
* Buhr or millstone formation without shells, and argillaceous sand.
* The upper freshwater formation, comprehending marles and buhrs with freshwater shells.
* Alluvium or earth of transportation, both ancient and modern, analogous to our gravel, &c. comprehending rounded pebbles, pudding stones, argillaceous marles and peat moss.
Of these the three first above the chalk are of marine origin, and they cover the whole of the bottom of the basin.
The gypsum and accompanying marles they imagine to have been formed chiefly in fresh water, from the fossils contained in them.
The next series of marles and sandstones containing only marine shells, shows the sea to have again covered the last formed strata.
Lastly, the upper freshwater formation demonstrates this place to have been a second time converted into a lake.
​Such are the leading features of these remarkable strata.
It is the object of the present paper to describe a similar series of formations; from which it will appear that the circumstances which gave rise to the alteration of marine and freshwater strata were subject at distant places to the same general laws, and were therefore extensive in operation: conclusions in themselves not uninteresting, and tending to throw some light on the later revolutions which our planet has undergone.
Sir Henry Englefield was the first who observed a range of chalk hills running from east to west across the middle of the Isle of Wight, and inclined at an angle of from 60° to 80°. An account of these strata appeared in the Transactions of the Linnean Society, 1802; but circumstances having prevented him from prosecuting these geological researches in person, at his request in the summer of 1811 I examined the connexion of the vertical strata of the Isle of Wight with those on each side which are horizontal, and also the continuation of this range to the west on the opposite shore of Dorsetshire.
The general result of this enquiry will be best understood from the following section across the Isle of Wight from north to south; see plate 11, fig. 1.
Plate 11, Fig. 1.
The inclined strata A, B, C, D, E, compose a range of hills that divides the island into two parts, extending from the Needles at the west end of the island to the Culver cliff at the east: at which places may be seen vertical sections at right angles to the direction of the range.
​The stratum marked A, is chalk with flints, which at the north side is in nearly vertical layers, the inclination becoming gradually less and less towards the south side, where they dip about 60°.
* is chalk without flints.
* chalk marl.
* calcareous sand-stone, with subordinate beds of limestone and chert.
* bluish-black marl.
* ferruginous sand and sand-stone, with potters' clay, slate clay, argillaceous limestone, wood-coal, &c. The part of this stratum in the middle ranges of hills inclines only a few degrees, extending to the south side of the island, where it is horizontal. It is to be remarked, that towards this side of the island there is a higher range of hills H, composed of horizontal strata which correspond exactly with a part of those of the highly inclined series of the middle range, not only in their nature, but in their order of superposition; thus irresistibly forcing upon us the conclusion, that they belonged to the same formation, and that they had probably at some period been continuous.
The strata G, to the north of these already mentioned, consist of a numerous alternating series in a vertical position, and are composed chiefly of sand and clay. These may be seen to great advantage in Alum bay, where they form cliffs about 200 feet in height.
The whole of the most northern part of the island, I, consists of nearly horizontal strata, which come up abruptly against those that are vertical, but are slightly curved at their junction with the latter. These, however, proved to be entirely different in their mineralogical characters and in the fossils which they contained, from the strata ​that I have described on the north side of the island, under the chalk.
Several of them were composed of a calcareous rock, either of a loose or compact texture; and an attentive consideration of this section, together with those of the opposite coasts of Dorsetshire, Hampshire, and Sussex, convinced me that the date of their origin was posterior to that of the chalk.
No distinct limestone stratum had been hitherto observed above any part of the chalk in this country, although it was well known that such were frequent in France. That this is the real position of the limestones near Paris could not be doubted, since the chalk is always reached in sinking to great depths. But the geognostic place of the strata on the north side of the Isle of Wight, was more difficult to ascertain; and it was only from many combined considerations that I was led to the conclusion, that they might be found to agree with some of those lately described by Cuvier and Brongniart, as contained in the basin of Paris.
These considerations were the following:
The chalk of England, although it appears upon the surface only in detached hills and patches, is actually continuous through considerable tracts of country, where it exists at great depths, as is now ascertained by numerous wells and other sinkings. In the order of position, which the strata of the chalk itself, and those which lie above and below it, bear severally to one another, there has been observed in distant places a remarkable agreement. And although occasional varieties may be noticed, in consequence of the defect or redundancy of any one stratum, yet the law of the Wernerian school seems to hold good; viz. that the order of the beds is never inverted.
This agreement renders it extremely probable that the corresponding strata, found in different parts of the same country, arose from ​the same cause, and at the same time; and favours the idea, that many of these, although now broken and unconnected, were originally continuous.
A part of the series which I deduced from observations made in the south-eastern part of England, is as follows, beginning with the uppermost.
* Alluvium, consisting of gravel, loam, sand, &c. and forming the surface or soil.
* Sand seen chiefly in the neighbourhood of Bagshot.
* Blue clay, with septaria and marine fossils, commonly called the London clay.
* Sand, plastic clay, &c.
* Chalk with flints.
* Chalk without flints.
* Chalkmarl, including what is called the grey chalk.
* Sandstone with green earth and mica, cemented together by calcareous matter, and containing subordinate beds of limestone and chert. This includes the firestone of Ryegate, and Kentish rag.
* Blueish black marl.
* Sand and sandstone, highly ferruginous, containing subordinate beds of clay, fullers earth, shale, bituminous wood, and limestone. This stratum forms the wealds of Kent and Sussex.
* A series of strata of shelly limestone, known by the name of the Purbeck stone, alternating with shale and marle. Some of the fossils of these strata strongly resemble freshwater shells: they appear to be the Cyclostoma, Planorbis, &c.
* Clay with gypsum.
* Portland oolite.
The strata of Alum bay, now seen in a vertical position, must have been originally quite horizontal, or nearly so. For it is not only extremely improbable that beds of such materials should have been formed in any other manner, but a circumstance which I noticed in Alum bay renders certain the original position of the sand and clay strata. In one of the vertical beds, consisting of loose sand, are several layers of flints, extending from the bottom to the top of the cliff; these flints have been rounded by attrition; are from one inch to eight inches in diameter, and appear to have belonged to the chalk. Now it is inconceivable that these flint pebbles should have been originally deposited in their present position; and they distinctly point out the original horizontality of this series. There are no signs of partial disturbance in the several beds, and it appears therefore that the whole have been moved together, either by elevation or subsidence into the vertical situation.
The strata of chalk have evidently suffered a change of position at the same time with the clay and sand; and since the vertical beds of Alum bay, G, are next to the stratum of flinty chalk, which, according to the regular order of superposition, is known to have been the uppermost of the chalk series, it follows, that they are of posterior formation. Moreover, the most northern of these vertical beds is a blue clay, agreeing with the London clay, a bed which always lies over the chalk.
​The chalk of the middle hills of the Isle of Wight dipping to the north, and that of the South Downs dipping to the south, it was an obvious inference that it might pass under the channel called the Solent, thus forming a basin. This idea was rendered still more probable on finding that the bottom of this channel consisted mostly of the London clay, which stratum is found under Portsmouth, whence it may be traced eastward, forming the lowermost bed next the sea all along the shore of Sussex to Pagham and Bognor, and westward to Stubbington cliffs, and along the coast of Hampshire to Hordwell and High cliffs. In all its characters and fossils, this bed was found to agree with the blue clay which lies over the chalk, in the counties of Kent, Surrey, Middlesex, Essex, &c. and with the most northerly of the vertical beds of Alum bay. Besides, the chalk itself lies at no great depth from the surface in all that part of Sussex south of the South Downs, and is even found on the shore at low water-mark at Middleton, two miles east of Bognor.
It appears, therefore, that between the vertical chalk-hills of the Isle of Wight and the South Downs there is a basin or hollow, occasioned by the disturbance of the whole mass of strata from below the chalk to the London clay, inclusive: and also that this disturbance took place at a period subsequent to the deposition of the last-mentioned stratum, since it is amongst those which have suffered a change of position.
From this it will be readily admitted, that all the beds situated within this basin lie above the London clay, and are posterior to it. Of this description are the horizontal beds of the most northerly part of the Isle of Wight; and since they come almost into contact
​with the vertical beds without suffering any considerable change in their dip, it should seem that they have been deposited on the sides of this basin subsequently to the disturbance of the strata already spoken of.
The above conclusions are confirmed by other circumstances.
These horizontal beds have no agreement with any of those beneath the chalk, nor indeed with any others yet observed in Great Britain; their mineralogical characters, and their fossils, are peculiar and distinctive. The calcareous beds contain numerous petrifactions of freshwater shells, and in others are found marine fossils agreeing with those described by Lamarck in the strata of the Paris basin. But fortunately, the inspection of specimens from the basin of Paris enabled me no longer to depend upon conjecture only as to the similarity of these formations. They had been given by M. Brongniart himself, in illustration of his memoir, to the Count de Bournon, who had deposited them in the museum of the Geological Society. The agreement of the strata of the two basins, not only with respect to the external characters of the calcaire d'eau douce, but also to its fossils, was thus rendered evident: and these specimens, so well authenticated, added one more proof (if more could be wanting) of the utility of such collections, and of the advantages to be derived from a liberal communication between men of science.
It is unnecessary to inform the Society that this circumstance produced another visit to the Isle of Wight and its vicinity, for the purpose of examining more particularly its basin, and the remains of its ancient lake. From this, compared with my former survey, I was enabled to add to the British strata the following, of later formation than the London clay.
* A calcareous stratum, containing only freshwater shells.
* Greenish marl, with marine shells.
* Marl with freshwater shells.
* Dark blue clay without shells.
These must be placed between the alluvium and the London clay, of the former list.
In the subsequent pages I shall describe more minutely the form of the basin of the Isle of Wight; and also that of a similar basin on which London is placed. I shall enumerate the strata and principal organic remains contained in each, and conclude by pointing out such circumstances of agreement or difference as I have been able to observe between them and the Paris basin.
II. Extent of the Isle of Wight Basin.
In tracing the margin of the cavity in which these horizontal depositions of the Isle of Wight are found, I shall begin with the south side.
The middle range of chalk hills in this island, together with the other highly inclined strata of Alum bay, form part of the ancient border. If we sail west from the Needles in the Isle of Wight, to Handfast point in Dorsetshire, we shall find that this vertical chalk range again makes its appearance in that coast, and may be traced thence through Corfe Castle to some distance beyond Lulworth; and from the correspondence in the line of direction of the Isle of Wight hills with those of Dorsetshire, and the general agreement in the position and nature of the strata, (the section of the Isle of Purbeck corresponding nearly to that of the Isle of Wight,) it appears extremely probable that at some former period these places were united.
The clay however over the chalk, and part of the chalk itself, ​in Dorsetshire, is horizontal, differing in this respect from their position in Alum bay. There must, therefore, have been some twist in the chalk stratum, a remarkable instance of which I discovered at the other end of the chalk range beyond Lulworth.
Since I shall have a future opportunity of making some remarks on the very singular stratification of these places, I shall only at present observe, that the highly inclined chalk from the Culver cliffs at the east end of the Isle of Wight to White Nose, in Dorsetshire, 5 miles west of Lulworth, formed the southern side of this depression in the chalk stratum. The north side of it may be traced in that range of hills called the South Downs, extending from Beechy Head, in Sussex, to Dorchester, in Dorsetshire. The strata of which these hills are composed, dip generally from 15° to 5° to the south; the inclination varying in different places. The south side of the basin therefore must have been extremely steep, while the slope of the north side was very gentle. The closing of this basin at the west is obscure, and cannot be distinctly traced; but the east is now entirely open, the sea passing through it.
III. Extent of the London Basin.
This extensive basin, like that of the Isle of Wight, is probably owing to a depression in the chalk stratum.
Its south side is formed by a long line of chalk hills, including those of Kent, Surrey, and Hampshire, called the North Downs, extending through Basingstoke to some distance beyond Highclere ​Hill, in Berkshire. Its western extremity is much contracted, and seems to lie somewhere in the vicinity of Hungerford. Its north-western side is formed by the chalk hills of Wiltshire, Berkshire, Oxfordshire, Buckinghamshire and Hertfordshire. The most northern part of this boundary has not yet been well determined. On the east it is open to the sea, the coasts of Essex, Suffolk and Norfolk, being sections of the strata deposited in it.
The dip of the chalk of the North Downs from Dover to Guildford is from 15° to 10°, but in the narrow ridge of chalk called the Hog's-back, extending from Guildford to Farnham, the dip is very considerable being above 45°. On the dip of the other sides I have had no opportunity of making any observations.
The depth of the chalk below the surface at London must be very considerable, since though wells have been sunk several hundred feet it has never been reached; but at a few miles south of the metropolis the chalk is frequently come to.
IV. Description of the Strata composing and contained in the Isle of Wight and London Basins; with a comparison between them and those in the Basin of Paris.
The authors of the French memoir, in order to obtain their general section, have collected the sections of various places; and by comparing them together have developed those alternations of marine and freshwater deposits, which are analogous to those we are now considering. I shall follow nearly the same method; but for greater simplicity I shall divide the formations composing our basins into
* Chalk formation.
* The lowest marine formation over the shell, including the plastic clay and sand, together with London clay.
* The lowest freshwater formation.
* The upper marine formation.
* The upper-freshwater formation.
* Alluvium.
Fortunately the complete series of these alternations may be seen at one place in the Isle of Wight, which leaves us no room to doubt their superposition; and when their characters have been studied in this spot, it is more easy to become acquainted with them in other places.
§ 1. Chalk Formation.
The south-east coast of England and that of the Isle of Wight afford us many excellent opportunities of examining the chalk. In numerous natural sections formed by cliffs, as well as in chalk pits, I have observed it as distinguished into at least three strata, each of which has peculiar and distinctive characters.
The lower stratum is more or less argillaceous, and constitutes what is called the chalk marl. Together with the other strata it frequently forms cliffs of considerable height, and though differing little from them in colour is easily distinguished by its constantly shivering with the frost, which always pulverizes a mass of it when exposed to the air for a few months; whereas the others resist the weather in a much greater degree, and are often even employed as a material for building.
​This chalk marl is never quite so white as chalk, having generally a tinge of yellow, and sometimes of grey and brown. It also contains nodules and beds of a more indurated marl, which is usually called the grey chalk from its dark colour, which varies from a light to a dark grey and brownish grey. Like all argillaceous limestones it possesses in a considerable degree the property of setting under water when calcined and made into mortar; and it has been used with great success for this purpose in building the London Docks. The part easily reducible to the pulverulent state by the moisture and frost is a most valuable manure when employed judiciously in certain soils. This stratum contains no flints.
The middle and upper strata consist of chalk of extreme whiteness and purity, and are chiefly distinguished from each other by the upper one containing layers of flint nodules which do not occur in the lower. The chalk without flints is most frequently somewhat harder than that with flints, and hence they are sometimes distinguished as the hard and soft chalk; but from some observations which I have made in Dorsetshire, it will appear that the hardness, or degree of induration, does not always mark a particular bed, the flint chalk being in some places much harder than that without flints in others.
On the subject of the nodules and laminæ of flint in the upper chalk, the observations of Sir Henry Englefield have thrown great light, and will be mentioned in his intended work on the Isle of Wight.
The several beds of these chalk strata, which vary in thickness from a few inches to several feet, are frequently separated from each other not only by layers of flint nodules but frequently also by a marl containing a considerable proportion of clay, and this substance also sometimes fills up the diagonal fissures which cross the strata. ​The workmen take advantage of this circumstance in quarrying the chalk.
The description given by M. M. Cuvier and Brongniart of the chalk of France appears to agree generally with that detailed above. They mention nodules of a harder chalk as occurring in layers in a softer. They observe that Werner has enumerated grey and brown among the colours belonging to chalk: and that in a great part of Champagne the chalk contains no flint, but it does not appear whether these varieties of chalk are on the continent confined to particular strata.
M. M. Cuvier and Brongniart remark that the chalk which forms the bottom of the Parisian basin, appears to have been consolidated before the deposition of the clay which covers it: a circumstance which they inferred from there being no transition of these into each other. A breccia is described as occupying the lower part of the basin at Meudon, composed of water-worn fragments of solid chalk cemented by a paste of clay, and situated between the chalk and the plastic clay. This circumstance, together with the irregular form of the bottom of their basin, seems to indicate a considerable action of water upon its surface, so as to render it now difficult to ascertain what might have been the last ​depositions of the chalk formation, or those which immediately succeeded it.
Some appearances shew that a similar action had taken place on the original surface of our chalk. Many very interesting sections may be seen in the County of Kent, where the chalk being at no great depth, its junction with the strata over it may be very conveniently studied. At Woolwich, on the top of the chalk, and between it and the superimposed sand, there are a number of flint nodules heaped on each other, which have evidently been displaced from their original matrix. In the numerous chalk pits, and where the roads are cut through the chalk along the south side of the Thames, as at Rochester, Gravesend, North Fleet, Greenhithe, &c. the junction of the chalk with the sand and gravel is remarkable for the deep indentations in the surface of the former, which upon examination I ascertained to be the sections of long furrows and of wells; these were apparently occasioned by the powerful action of water prior to the deposition of the sand and gravel which now fills up these hollows: the same may be seen still better at Purfleet.
The present surface of the chalk stratum is also frequently covered by water-worn pieces of chalk and flint imbedded in clay or alluvial deposits.
The cliffs between Brighton and Rottendean are of a singular character, and merit a particular description. The shore consists of the solid chalk, which is seen running out to a considerable distance into the sea, and dipping a few degrees to the south. This stratum forms six or seven feet of the lower part of the vertical cliff; and on that are placed several layers of loose flints, evidently rounded by attrition and piled on one another. Over this is an irregular bed consisting of pieces of chalk and smaller pieces of flints, both of which have undergone the same process; and the interstices are ​filled up with clay and loose chalk or marl: over this is another layer of pebbles, and again clay and chalk and fragments of flints; and these follow in succession, but very irregularly, to the top of the cliffs which is at least seventy or eighty feet in height. These materials are in general quite loose, being simply heaped or laid on each other; but sometimes masses of it are cemented together by stalactitical matter, and when the cliff falls, form blocks of great size and hardness.
It is impossible to see this cliff without immediately perceiving that it does not owe its existence to original stratification; but that it is simply the section of an immense heap of fragments of chalk and flints mixed with clay and sand, the whole of which has at some distant period been subjected to the action of water; and that it has been thus deposited upon the solid chalk stratum which is now seen below it.
In tracing this vast collection of water-worn materials, we find that it forms a considerable hill behind the town, and that it joins to the side of the range of hills called the South Downs.
In Alum bay in the Isle of Wight, however, the stratum immediately next to the flinty chalk, and consequently deposited upon it, consists of a white chalk marl without flints. Its nature is sufficiently shewn by its pulverizing with the frost; and the rains wash it down, so that its situation is marked by a deep hollow. There is some appearance here therefore of a transition of the last portions of the chalk into the clay which succeeded it; and, the usual rounded flint pebbles over the chalk and the other signs of disturbance being there wanting, it is possible that we have in that place the original succession of depositions. In many parts of Sussex also, south of the South Downs, as at Emsworth, Lavant, Siddlesham, South and North Bersted, Middleton, &c. I found ​pits of a marle without flints, and which is evidently over the chalk. The same marl is also to be found in Dorsetshire west of Corfe Castle. I have not however heard of its existence in the London basin.
The agreement of the fossils of our chalk with that of France has been already pointed out by Mr. Parkinson in his Memoir “on some of the Strata in the neighbourhood of London,” in the first volume of the Transactions of this Society. In the following lists I have been favoured by his assistance in the endeavour to appropriate the fossils to their peculiar beds.
In the Chalk with Flints. :
| Asteriæ | resembling | resembling |
| | Pentagonaster semilunatus | Pentagonaster semilunatus |
| | ────── | regularis |
| | Pentaceros lentiginosus | Pentaceros lentiginosus |
| | Stella lumbricalis, lacertosa, corpore spherico. | Stella lumbricalis, lacertosa, corpore spherico. |
| Echini | of the following families. | of the following families. |
| | Cidaris | $\left.{\begin{matrix}\ \\\ \\\ \\\ \\\ \end{matrix}}\right\$ several species. |
| | Cassis, | $\left.{\begin{matrix}\ \\\ \\\ \\\ \\\ \end{matrix}}\right\$ several species. |
| | Spatangus, | $\left.{\begin{matrix}\ \\\ \\\ \\\ \\\ \end{matrix}}\right\$ several species. |
| | Fibula, | $\left.{\begin{matrix}\ \\\ \\\ \\\ \\\ \end{matrix}}\right\$ several species. |
| | Conulus, | $\left.{\begin{matrix}\ \\\ \\\ \\\ \\\ \end{matrix}}\right\$ several species. |
| Spines of the foregoing: particularly those resembling the belemnites as described by Mr. Parkinson. |||
| Serpulæ, particularly the serpula of Mr. Parkinson's organic remains, vol. 3. pl. 7. fig. 11. |||
| Cardium. |||
| Spondylus. |||
| Ostrea, several species. |||
Pecten, several species. :
Chama? :
Terebratula, many species. :
A longitudinal transversely rugose ostrea-form bivalve of a fibrous structure. :
Fragments of mother fibrous shell of a large size, of an unknown genus. See Hark. Organic Rem. pL 5. fig. 3. :
Alcyonia, sponges, and numerous unknown zoophytes. :
A ramose madrepore. :
Several species of minute encrini, figured by Mr. Parkinson. :
In the Chalk without Flints. :
Echini: several of the same families as those in the chalk with flints. Many of them, however, particularly the Cassides, differing much in their forms from the above. :
Spines of echini: and particularly those described by M. Braard as resembling the belemnite. :
Patella. :
Trochus. :
Serpulæ, several species. :
Belemnites. :
Lima? :
Fish, too much mutilated to ascertain the genus. :
Palates, scales, vertebræ and teeth of fish. :
Cancri. :
In the Chalk Marl. :
Scaphites: a new genus by Mr. Parkinson. See his Organic Remains, vol. 3. :
* Turrellites, three species. ||
* Trochus. ||
* Madreporæ. ||
| Belemnites | Perhaps two species: they appear to be different from those in the compact limestone. |
| Lenticulites rotulata. ||
| Lituolites nautiloidea. ||
| ————— difformis. ||
| Pinna | It is not certain that the large fragments of 12 millimetres in thickness and of a fibrous texture, which are found in the chalk belong to this genus. M. Defrance has portions of a hinge which indicate a different genus. Cuv. p. 11. ​ |
| Mytilus | very different from those of the calcaire grossier. |
| Cardium? | |
| Ostrea vesicularis. ||
| ———— deltoidea. ||
| Pecten | M. Defrance has observed 2 species. |
| Crania | It was adherent and differing in that from known species. |
| Perna? | |
| Terebratula, many species. | |
| Spirorbis. | |
| Serpula. | |
| Ananchites ovatus | The shell is changed into calcareous spar, and the internal part is converted into flint. |
| Spatangus Cor anguinum Kl. ||
| Porpites. | |
| Caryophyllia | |
| Millepora | These are often in the state of brown oxide of iron. |
| Alcyonia. | |
| Shark's teeth. | |
| e, | Greenish yellow sand. |
| f, | Yellow sand with ferruginous masses. |
| g, | Greenish sand, like e. |
| h, | Yellow, white, and greenish sand. |
| i, | Whitish sand, with thin stripes of clay. |
| k, | White and yellow sand. |
| l, | Light green sand. |
| m, | Ferruginous sand stone. |
| n, | Yellow sand with a few red stripes. |
| | Next to this, and in the middle of the bay, is a very numerous succession of beds, which contain a large proportion of pipe-clay of various colours, white, yellow, grey, and blackish. These alternate with beautifully coloured sands. The clay is sometimes in beds several feet in thickness, without any admixture, and sometimes in laminæ not a quarter of an inch thick with sand between them. They are generally as follows: |
| o, | Blackish clay with stripes of white sand. |
| p, | Sand intensely yellow. |
| q, | Very white sand. In the middle of this there is a layer of small siliceous nodules, quite white, easily frangible, and of an earthy texture; they are water-worn, and seem to have been derived from decomposed flints. |
| r, | Sand of a crimson colour. |
| s, | Pipe clay with sand stripes. Here it runs into the sea, and may be traced across the beach. |
| t, | Yellow sand with some crimson. |
| u, | Pipe clay, white and black, with stripes of sand. In the middle there are three beds of a sort of wood coal, the vegetable origin of which is distinctly pointed out by the |
| | fruits and branches still to be observed in it. It sometimes splits into irregular layers in the direction of the bed, and the cross fracture is dull and earthy. It burns with difficulty, and with very little Same, giving out a sulphurous smell. |
| v, | Yellow and white sand, with crimson and grey stripes. |
| w, | Five beds of coal similar to that above-mentioned, each a foot thick. |
| x, | Whitish sand and brownish pipe clay. |
| y, | Whitish sand with stripes of deep yellow. |
| z, | Several layers of large water-worn black flint pebbles, imbedded in deep yellow sand. |
| B, | A stratum of blackish clay, with much green earth and septaria. In this green earth are a prodigious number of fossil shells, but in a very fragile state. They correspond exactly with those of Stubbington and Hordwell. |
| Sand on the top | 10 |
| Blackish brown clay | 14 |
| Wood coal | 3 |
| Refuse clay | 5 |
| Fine white potter's clay | 6 |
| Dark brown clay | 2 |
| Fine white potter's clay | 6$\scriptstyle {\frac {1}{2}}$ |
| | 46$\scriptstyle {\frac {1}{2}}$ |
Feet :
| 6 | 9 | Vegetable mould. |
| 9 | 0 | Brown clay. |
| 26 | 8 | Gravel with water. |
| 3 | 0 | Blue clay. |
| 5 | 1 | Loom. |
| 3 | 9 | Blue slay with bivalve shells. |
| 7 | 6 | Gravel stones imbedded in a calcareous rock. |
| 4 | 6 | Light blue soil with pyrites. |
| 1 | 9 | Green sand. |
| 8 | 4 | Leafy clay. |
| Names given by Lamarck. | Linnean names. | Place where they have been found. |
| Astriotæ | Astroitæ | Sheppey |
| Calyptrea trochiformis | Trochus apertus, Brander | Hordwell, Bognor, Woolwich, Plumstead |
| Conus | Conus | Hordwell, Stubbington |
| Cyprea pediculus | Cyprea pediculus | Stubbington, Highgate |
| Terebellum convolutum | Bulla sopita, Brand. | Hordwell |
| Oliva | Voluta | Alum-bay |
| Voluta spinosa | Strombus spinosus | Alum-bay |
| ──── musicalis | ──── luctator | Hordwell |
| ──── bicorona | ──── ambiguus | Hordwell |
| ──── crenulata | Murex suspensus | Hordwell, Alum-bay |
| | Voluta ampullaria | Brentford, Alum-bay |
| Buccinum undatum | | Alum-bay |
| Harpa | | Brentford |
| Cassis carinata | Buccinum nodosum, Bran. | Stubbington, Highgate |
| Rostellaria macroptera | Strombus amplus | Hordwell, Highgate |
| Murex tripterus | Murex tripetrus | Hordwell |
| ──── tricarinatus | ──── asper | Hordwell |
| ──── tubifer | ──── pungens | Hordwell |
| | ──── contrarius | |
| | ──── whirls the right way |
| Fusus longævus | ──── longævus | Hordwell |
| ──── clavellatus | ──── deformis | Hordwell |
| ──── rugosus | ──── porrectus | Hordwell |
| Pyrula nexilis | ──── nexilis | Hordwell |
| Pleurotoma? | | Alum-bay |
| Cerithium gigantum | Murex | Stubbington |
| Cerithium, another variety, but too mutilated to ascertain the species | $\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,$Murex | Sheppey |
| Trochus agglutinans | Trochus umbilicaris, Bran. | Stubbington, Hordwell |
| ──── monilifer | ──── nodolusus | Hardwell |
| Solarium caniculatum or | Turbo, tab. 1. fig. 7 & 8. Brander | Hordwell |
| Delphinula? | Turbo, tab. 1. fig. 7. Brand. | Hordwell |
| Turritella terebellata | Turbo terebra | Hordwell, Stubbington, Alum-bay, Selsea |
| ──── imbricatoria | ──── editus | Hordwell, Stubbington, Alum-bay, Selsea |
| ──── multisulcata | ──── vagus | Hordwell, Stubbington, Alum-bay, Selsea |
| Ampullaria patula | Helix mutabilis | Hordwell, Stubbington, Bognor ​ |
| Dentalium elephantinum | Dentalium elephantinum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$Hordwell, Sussex |
| ───── entalis | ───── entalis | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$Hordwell, Sussex |
| ───── dentalis | ───── dentalis | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$Hordwell, Sussex |
| ───── striatulum | ───── striatulum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$Hordwell, Sussex |
| Serpula | Serpula | Hordwell; Bognor, Sheppey |
| Nautilus imperialis | | Sheppey, Highgate, Brentford |
| ───── pompilius | | Sheppey, South-end, Highgate, Brentford |
| ───── centralis | | Richmond |
| Lenticulina rotulata | | Stubbington |
| Nummulites lævigata | | Brackelsham in Selsea |
| Pinna, 2 species | Pinna | Bognor |
| Mytilus modiola | Mytilus | Bognor, Highgate |
| Pectunculus pulvinatus | Arca glycemeris | Bognor, Stubbington, Essex |
| Cardium porulosum | Cardium porolusum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right\}\,$ Hordwell |
| ───── asperulum | ───── asperulum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right\}\,$ Hordwell |
| ───── obliquum | ───── obliquum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right\}\,$ Hordwell |
| Crassatellata lamellosa | Tellina sulcata | Hordwell |
| Venericardia planicosta | | Stubbington, Selsea |
| Capsa rugosa | Venus deflorata | Pagham |
| Chama lamellosa | Chama squamosa | Hordwell |
| ───── calarata | | Hordwell |
| ───── sulcata | | Hordwell, Stubbington, Alum-bay |
| Ostrea edulis | Ostrea edulis | Bognor, Selsea, Essex |
| Pyrus bulbiformis | | Hordwell, Stubbington; Alum-bay |
| Caryophillia | Turbinated Madrepores | Sheppey |
| Teredo navalis | Teredo navalis | Stubbington, Portsmouth, Sheppey, Bognor, Highgate |
| Jaw of Crocodile | | Sheppey |
| Testudo or Turtle | | Sheppey |
| Various Fish, but too mutilated to ascertain the species | | Sheppey |
| Fish teeth, supposed by some to belong to the shark | | Sheppey, Stubbington, Highgate |
| Molar teeth of fish, called Bufonites | | Sheppey |
| Palatum Scopuli and other palates of fish | | Selsea, Sheppey ​ |
| Tongue of fish of the genus Raia | | Sheppey |
| Tail of the String Ray | | Highgate |
| Scales of fish | | Sheppey |
| Vertebræ of various species of fish | | Sussex, Sheppey, Highgate |
| Cancer, above 20 species of Crabs | | Sheppey |
| ———— Gammarus or Lobster | | Sheppey |
| ———— Crangon or Prawn | | Sheppey |
| Wood, often pierced by the Teredo navalis &c filled with pyrites or calacareous spar | | Portsmouth, Sheppey, Highgate |
| Fruits, branches, excrescences, ligneous seed vessels and berries impregnated with pyrites | | Sheppey, Emsworth in Sussex |
| Nummulites lævigata | Cerithium giganteum |
| ————— scabra | Lucina lamellosa |
| ————— numismalis | Cardium porulosum |
| ————— &c. | Voluta cithara |
| Madrepora | Crassatella lamellosa |
| Astraæ | Turitella multisulcata |
| Caryophyllia | Ostrea Flabellula |
| Fungites | ——— Cymbula ​ |
| Middle beds ||
| Cardita avicularia | Citheria nitidula |
| Orbitolites plana | ———— elegans |
| Turritella imbricata | Miliolites |
| Terebellum convolutum | Cerithium? |
| Culyptræa trochiformis | Articulate bodies |
| Pectunculus pulvinatus | resembling vegetables |
| Upper beds ||
| Miliolites | Cerithium lapidum |
| Cardium lima or obliquum | ———— petricolum |
| Lucina saxomrum | Corbula anatina? |
| Ampullaria spirata | ———— striata |
| Cerithium tuberculatum | Impressions of leaves |
| ———— mutabile | |
* Nummulites lenticularia
* ———— lævigata
* Turritella terebellata
* ———— imbricataria
* Crassatella sulcata
* Venericardia planicosta
* Sharks' teeth
| | | Feet. | Feet. |
| 1. | Blue clay | depth unknown | depth unknown |
| 2. | Sand | 50 | 0 |
| 3. | A Siliceous limestone called rag | 0 | 6 |
| 4. | Sand | 0 | 8 |
| 5. | Siliceous limestone | 0 | 6 |
| 6. | White shell-marl | 0 | 10 |
| 7. | Siliceous limestone | 1 | 6 |
| 8. | Limestone composed of the fragments of freshwater shells | 1 | 6 |
| 9. | Ditto, the fragments more apparent | 2 | 0 |
| 10. | Ditto, the fragments still larger | 4 | 0 |
| 11. | Ditto, fragments still coarser | 2 | 0 |
| 12. | Blue Clay, in which are many large and loose masses which appear to belong to the upper Freshwater formation. |
| Names given by Lamarck. | Linnean names. |
| Cerithium plicatum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – lapidum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – mutabile | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – semicoronatum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – cinctum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – turritellatum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – tricarinatum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| Cyclas deltoidea | Venus |
| Cytherea scutellaria | Venus |
| Ancilla buccinoides | Voluta |
| – – – – subulata | Voluta |
| Ampullaria spirata | $\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,$ Helices |
| – – – – – depressa? | $\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,$ Helices |
| Murex reticulatus |
| Bivalve apparently of the genus Erycina |
| Helicina? |
| Murex nodularius |
| Melania? They are however too much injured about the mouth to determine their genus with certainty |
| Another species of Melania corresponding to those of Plumstead |
| Natica Canrena | Nerita |
| Ostrea, approaching to deltoidea |
| – – – – specific characters not evident, but different from the last. |
| Names given by Lamarck. | Linnean names. |
| | Patella ungaria |
| | – – – – lævis |
| Patella spirorostris | – – – – fusca |
| Fissurella labiata | Patella |
| – – – – – emarginula | – – – – fissura |
| Calyptrea sinenis | – – – – sinensis |
| Eburna glabrata | Buccinum glabratum |
| – – – – | Murex corneus |
| – – – – | – – – – erinaceus |
| – – – – | – – – – contrarius |
| – – – – | Trochus sulcatus |
| – – – – | – – – – – alligatus |
| Ampullaria rugosa |
| Natica canrena |
| – – – — glaucina |
| Mactra |
| Venericardia senilis | Arca senilis |
| Lucina | Venus gallina |
| – – – | Solen siliqua |
| Pholas crispata |
| – – –– – – | Ostrea deformis |
| Pecten plebeius |
| – – – infirmatus |
| Balanus |
| Cytherea (bom-bees) | Ostrea Hippopus |
| – – – – – plana | – – – – Pseudochama |
| – – – – – elegans | – – – – longirostris |
| – – – – – semisulcata | – – – – canalis |
| Cerithium plicatum | – – – – cochlearia |
| – – – – – cinctum | – – – – cyathella |
| Ampullaria patula | – – – – spatulata |
| Cardium obliquum | – – – – linguatula |
| Nucula margaritacea | Bones and parts of Fishes |
| Patella spirorostris—Cuv. p. 187. ||
| In the upper marine sand stones. ||
| Oliva mitreola | Pectunculus pulvinatus |
| Fusus, resembling longævus | Crassatella compressa? |
| Cerithium cristatum | Donax retusa? |
| – – – – – – lamellosum | Cytherea nitidula |
| – – – – – – mutabile? | – – – – – lævigata |
| Solarium? | – – – – – elegans? |
| Melania costellata? | Corbula rugosa |
| Melania? | Ostrea flabellula |
| Names given by Lamarck. | Linnean names. |
| Cerithium turritellatum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – denticulatum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – serratum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – claviculatum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – mutabile | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – cinctum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| – – – – – semicoronatum | $\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,$ Murices |
| Cytherea scutellaria | Venus |
| Cyclas deltoidea |
| Calyptrea trochiformis | Trochus apertus |
| to which I have added |
| Ancilla Buccinoides | Voluta |
| At Plumstead. ||
| Melania | Helix |
| Arca | Arca |
| Ampullaria | Helix |
| Calyptrea trochiformis |
| Cyclas |
| and Mr. Parkinson has since found |
| Nucula margaritacea | Arca nucleus |
| Teeth of fishes |
| At Newhaven. ||
| Cerithium denticulatum | Murex |
| Cytherea scutellaria | Venus |
| Ostrea | Ostrea |
| Names given by Lamarck. | Linnean names. | Linnean names. |
| Planorbis, much resembling that which Brongniart says approaches to P. cornu | $\left.{\begin{matrix}\ \\\ \\\ \end{matrix}}\right\$ | Helix planorbis |
| Planorbis, two other species | $\left.{\begin{matrix}\ \\\ \\\ \end{matrix}}\right\$ | Helix planorbis |
| Planorbis, much resembling P. prevostinus | $\left.{\begin{matrix}\ \\\ \\\ \end{matrix}}\right\$ | Helix planorbis |
| Ampullaria | Helix | Helix |
| Cyclostoma | Helix | Helix |
| Limneus longiscatus | Helix | Helix |
| ────── acuminatus |
| Limneus | corneus |
| | perhaps a large specimen of L. longiscatus |
| Gyrogonites ||
| Cyclostoma elegans antiquum | Limneus inflatus |
| Potamides Lamarckii | Bulimus pygmeus |
| Planorbis rotundatus | – – – – – terebra |
| – – – – – cornu | Pupa Defrancii |
| – – – – – prevostinus | Helix lemani |
| Limneus corneus | – – – Desmarestina |
| – – – – – fabulum | Gyrogonites |
| – – – – – ventricosus |
* ↑ A detailed description of the Isle of Wight is now preparing for the press by Sir Henry Englefield, who has permitted me to communicate to the Society many of the observations which I made at his request with the view of completing his work.
* ↑ It was this chalk, together with the vertical strata of Alum bay, and the horizontal strata on each side, that were first observed and described by Sir H. Englefield.
* ↑ Other divisions of these strata have been made, and the cause of the differences has already been alluded to. Not every member of the series is perfectly continuous or of uniform thickness; so that when any one is wanting, beds, usually separate, are brought into immediate contact. In making a classification of these beds, those should be considered as principal members, which are most rarely deficient in an extensive tract of country.
* ↑ Having by the kindness of Mr. Holloway, of Portsmouth, become familiar with the fossils of Stubbington, I readily perceived their agreement with the above-mentioned stratum in Alum bay.
* ↑ The drawings and description of this, as well as of many other parts of this remarkable coast, will be found in the above-mentioned work now preparing for publication, by Sir H. Englefield.
* ↑ For the pointing out of this fact, as well as for much important information respecting the extent of the chalk, I am indebted to G. B. Greenough, Esq. V.P.G.S.
* ↑ In using the word formation I have followed the example of M. M. Cuvier and Brongniart, who have employed it to express an assemblage of beds of the same nature, or of a different nature but formed during the same epoch.
* ↑ A singular circumstance is mentioned respecting the chalk of France to which we have nothing analogous in this country. In Champagne there are immense plains of chalk absolutely deprived of vegetation, except where patches of the calcaire grossier occur as islands or oases in the midst of these deserts. And M. Cuvier observes that many parts of this tract have not perhaps been visited for ages by any living being: no motive existing that could induce any to wander there. In England every part of our chalk is completely covered by vegetable soil, which although very thin on many parts of our downs or smooth hills, yet affords support to peculiar grasses and other vegetables, on which are pastured vast quantities of sheep. The chalk of Franco is said to contain 11 per cent. of magnesia, to which the barrenness may be owing.
* ↑ On the authority of Mr. Parkinson I notice that the supposition of having discovered a specimen of Trigonia in chalk is erroneous. This belongs only to inferior strata.
* ↑ See the paper on this subject, by Sir Henry Englefield, in the Transactions of the Linnean Society.
* ↑ Hence the country on the northern side of London is so thinly inhabited.
* ↑ One of these prodigious falls of the chalk cliffs, which make a residence near them frequently so dangerous, occurred a few days before my visiting this spot, accompanied by a remarkable circumstance. The clergyman of East Dean, who was walking near the brink of the precipice, perceived the ground to give way under him, and had the presence of mind to escape over the rent that was forming at some distance from the edge of the cliff. In a few seconds, the mass of chalk which he had stood on, to the extent of 300 feet in length, and 70 or 80 in breadth, fell with a tremendous crash. In going from Newhaven round Beachy Head, under the cliff at low water, I passed over these ruins, which were truly terrific, and observed that their fall had been occasioned by the sea acting on the chalk marl, and thus undermining the chalk; the former from the dip of the strata, just begins to appear at the bottom of the cliff at this spot. It may be proper to mention that this place is highly deserving to he visited, on account of the fossils to be seen in the chalk and green sand; among these I remarked many large madrepores, and some very large and entire shells of the fibrous kind, the fragments of which are so numerous in the chalk.
* ↑ It will be an interesting investigation for the experienced botanist to trace the living analogues of these ancient productions of this part of the earth. Such of them as have been recognised are found to belong to species now growing only in the torrid zone; thus adding to the evidence afforded by the animal remains of the great change that must have taken place in the climate.
* ↑ The only shells which I noticed thus alternating with those of freshwater, appeared to belong to the genus Cerithium, but not having specimens of them it has since occurred to me, and it will deserve future observation, whether these were not the Potamides Lamarkii. They are abundant at Gurnet Point.
* ↑ Since the reading of this paper I have been favoured by the Rev. William Buckland, Prof. of Mineralogy, Oxford, with specimens of freshwater shells which he has collected at Hordwell cliff. They consist of the lymneus, planorbis, cyclostoma, and a bivalve resembling a freshwater mytilus. From the state of the fossils, and the nature of the stratum in which they were imbedded, they would appear to belong to the lower freshwater formation.
* ↑ It is not a little singular that some of the smaller upright stones of Stonehenge consist of a sort of greenstone, and must therefore have been brought from very great distance, no such rock occurring in the neighbourhood.
* ↑ Specimens of these collected in the neighbourhood of High Wycombe, by the Hon. Henry Grey Bennett, Pres. G. S. are deposited in the Museum of the Society.
* ↑ These were found in some specimens of clay containing also freshwater shells which were dug out of a deep well at Newport. But as no distinct account was kept of the strata passed through, it is not certain to which of the freshwater formations they belong.
* ↑ It is proper to observe that the Potamides of Lamarck is a Cerithium. But having considered the cerithia as marine shells, he thought it proper, on finding a species among the freshwater shells, to regard this as of a distinct genus; founding the distinction not on any difference in its form, but on the difference of the water in which it had lived.
* ↑ The Egyptian pebbles are said to occur in a similar situation.
* ↑ A very fine example of one occurs in a specimen in the museum of the Geological Society, presented by Leonard Horner, Esq. It is a small bivalve resembling a pecten.
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Errata
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