Quarterly Journal of the Geological Society of London/Volume 26/On the Superficial Deposits of the South of Hampshire and the Isle of Wight

by Thomas Codrington

1. On the Superficial Deposits of the South of Hampshire and the Isle of Wight. By Thomas Codrington.

[Plates XXXVI. & XXXVII.]

Contents.

I. Introduction.

II. The mainland of Hampshire.
a. The New-Forest district.
b. East of Southampton Water.
c. Materials and nature of the gravel.
d. Mammalian remains and Flint-implements.

III. The Isle of Wight.
a. Gravel on the high ground of the north of the island.
b. Gravel on the south coast.
c. Gravel at Freshwater Gate.
d. Wasting of the coast, and origin of chines.
e. Gravel section at Foreland.

IV. General considerations. a. Connexion of the Isle of Wight with the mainland.
b. Age of the gravel at different levels.
c. Conditions under which the gravel was deposited.
d. Upheaval since the human period.
e. Subsidence.
f. Denudation.

V. Summary.

I. Introduction.

The district of which it is proposed to treat in the following paper, is comprised between Poole and Portsmouth, and extends inland to Wimborne, Downton, Bramshaw, Romsey, and Bishopstoke; it also includes the Isle of Wight.

Tertiary formations occupy the whole of the area, with the exceptionof the southern part of the Isle of Wight; and the surface is very generally covered with superficial deposits, which are the immediate subject of this paper.

The rivers Frome, and Trent or Piddle, enter Poole harbour on the west, and the Stour, Avon, Test, Itchen, Hamble, and Titchfield rivers flow through the district. All these rivers, as well as the Medina, Tar, and Brading rivers, in the Isle of Wight, rise in the chalk, or in beds not much below it, and after draining a considerable extent of chalk-country, pass through the Tertiary area to the sea. The Avon water, Boldre, and Exe or Beaulieu river, rise among the Tertiary beds of the New Forest, of which they drain the larger portion.

Among those by whom the superficial deposits of the district have been noticed, are Sir C. Lyell, Messrs. Webster, Prestwich, Trimmer, E. Forbes, Godwin-Austen, Bristow, Evans, &c. Of late years, the discovery of numerous flint implements along the coast between Southampton Water and Gosport, near Bournemouth, and more recently near Southampton, and near Lymington, has given a fresh interest to the gravel from which they are derived; and the publication of the new Ordnance Maps with levels over a large part of the district, has facilitated the construction of many accurate sections of the surface. For the western part of the district, where the new Ordnance Survey is unfinished, levels have been supplied me by permission of Sir H. James, from which, and from other sources, as well as from personal observation, the sections have been extended in that direction.

The sections (figs. 1 to 10, Pl. XXXVII.) are selected from many others constructed; they are drawn to a scale of two miles to an inch horizontal, and 800 feet to an inch vertical. The heights in feet above the mean level of the sea are figured at numerous points, and the position of the lines of section are shown upon the map (Pl. XXXVI.).

 

II. The mainland of Hampshire.

(a) The physical features of the country, and its superficial deposits, are so closely connected that they must be considered together. The New Forest, and the neighbouring country between Poole and Southampton Water, is characterized by high level plains, very generally covered with gravel or brick-earth. On closer examination, these plains are found to be portions of a tableland with a very gradual southern slope, through which the larger rivers flow in well-defined valleys, and which has been a good deal cut up and over large areas entirely removed by the action of the tributary streams flowing in what arc locally called the " bottoms."

Section No. 1, from Fordingbridge and Breamore to Bramshaw, and No. 2, from Poole to Southampton Water, which are nearly on the line of strike of the general surface of the country, will illustrate its tabular character and the way in which the rivers intersect it. Theextension inland of the tableland is best seen on the east of the Avon, where it can be followed from the coast northwards for upwards of twenty miles to a gravel-capped escarpment, 420 feet above the sea, and 200 feet above the ground immediately to the northward, extending from Downton Common to Bramshaw. It is easy to see that the high plains, such as Picked Plain, Bratley Plain, and Ocknell Plain, although separated by deep valleys or " bottoms," form parts of one continuous tableland, and nowhere is this more evident than near the highest part between Downton, Fordingbridge, and Bramshaw. The eye there ranges over an extensive plateau curiously intersected by valleys 100 to 150 feet deep, by which the tabular appearance of the surface is, however, but little affected.

Section No. 3 commences at the coast near High Cliff, two miles east of the mouth of the Avon, where the cliff is 96 feet high, and is capped with 18 feet of gravel, and extends by two lines branching at Bratley Plain, to the northern escarpment near Bramshaw Telegraph, and at Blackbush Plain, respectively 419 feet and 397 feet above the sea. From the coast to the escarpment the ground has a uniform inclination of about 20 feet per mile, or one-fifth of a degree with the horizon. The surface is generally covered with gravel, which appears to thicken as the ground drops towards the valleys; the sides of the valleys are free from gravel, and the bottoms contain a gravel much mixed with locally derived clay and marl, and distinct from that covering the plains.

The regularity of the surface of the plains, where they are not cut up by streams, is very remarkable, more so on the ground than would perhaps appear from some of the sections, in which the vertical heights being necessarily greatly exaggerated, every irregularity is magnified to about thirteen times its natural scale.

To the westward of the Avon, the triangular tableland between Christchurch, Wimborne, and Poole is cut off on the north by the Stour valley. It varies in height from 100 feet near the coast to 190 feet towards Wimborne, and sections of the gravel covering it are seen along the coast, in the railway-cutting between Christchurch and Bournemouth, in the cutting south of Wimborne, and in numerous gravel-pits. On the north of the Stour at Wimborne, Canon Hill and Cole Hill are capped with gravels at a level corresponding to those of the plains to the south ; and still more inland, Chalbury Hill and Pistil Hill are covered with flint-gravel at greater elevations. The latter, a detached flat-topped hill, 320 feet above the sea, corresponds exactly in level with the plain on the opposite side of the Avon, and appears to be the remnant of a sloping tableland, of which the mass has undergone destruction by the action of the Stour, Blackwater, and Avon. Generally the country near the confluence of these rivers is at a much lower level than the high plains, ranging from 30 to 80 feet above the sea, or about 30 feet above the rivers. Somerley Heath, and Alderholt Heath, although 130 feet above the sea, are still 170 feet lower than the plains on the other side of the Avon, and immediately opposite them.

The bottom of the valley of the Avon is shown by a dotted line on section No. 3. Its fall is at the rate of from 8 feet per mile near Hale to 3 feet per mile near the sea; so that while the tableland near Christchurch is but 83 feet above the valley, at Hale the high plain of Hatchet Green is 300 feet above it.

Bordering on the valley between Fordingbridge and Ringwood, at levels approaching the tableland in height, there are terrace-like plains, which are well seen from the high ground on the opposite or western side of the valley.

On the east of section No. 3 the gravel-covered tableland stretches northward from Barton and Hordwell Cliffs till it is interrupted by the Avon-water valley. The tabular character is carried on by plains at corresponding levels near Wilverley; and beyond an area comparatively low, and drained by numerous tributaries of the Boldre river, is the high ground near Stoney Cross and Castle Malwood, which is continuous with Ocknell Plain, 270 feet above the sea, and gravel-covered. Section No. 4 illustrates the rise of the tableland from the coast to the Avon-water valley and to Wilverley, and shows how a prolongation of the same slope northwards would coincide with the high ground near Stoney Cross.

A section of the gravel covering the tableland is seen in the cliffs between Poole Harbour and the entrance of the Solent. Westward of Poole Harbour there is no gravel on the coast, though a patch occurs at a high level in the valley of the Frome near Rempston House; but between Poole and Bournemouth the cliffs are capped with gravel at from 100 to 120 feet above the sea. It is from this gravel that the flint implements found on each side of Bournemouth are derived. The section in the cliffs is nearly the same as that shown in section No. 2, the general level of the tableland near the coast at Bournemouth being about 120 feet above the sea. Except where it is intersected by the Bournemouth valley or by chines, the gravel-bed is continuous, and from 8 to 15 feet thick, to within about a mile from the mouth of the Avon; there the tableland ends, and a cliff not more than 10 or 20 feet high, is composed of what appear to be the gravel-beds of an old channel of the Avon or Stour, which reach as low as high-water mark. Between them and the present mouth of the river, Hengistbury Head rises to 120 feet, and is capped with the older gravel. About a mile eastward from the mouth of the Avon, the junction of the valley-gravels with the gravel of the plains is seen near Highcliff, and was noticed long ago by Sir Charles Lyell^[1] and by Mr. Godwin-Austen^[2]. From this point to Milford the gravel is again continuous, except where Chuton Bunny and Becton Bunny cut through it. In Barton and Hordwell cliffs the thickness is now as much as from 18 to 20 feet, while formerly, it was much more. In 1757^[3] and 1789–1794^[4] the gravel in Hordwell Cliff is described as being from 18 to 20 yards thick; and later, in 1821, Mr. Webster^[5] gives the thickness in Barton and Hordwell cliffs as at least 50 feet. As the coast is wasting at the rate of a yard a year, the cliffs which exhibited this thickness of gravel were from 60 to 80 yards in advance of the present coast, and inland the thickness diminishes still more, being only 9 feet in pits about half a mile from the cliffs.

Chuton and Becton Bunnies are cut out in the bottom of higher and broader valleys, on the flanks of which the gravel thins out. The chines in the sandy cliffs to the westward of Bournemouth furnish many sections in which the relations of the older valley and the chine with the gravel covering the plain can be observed. In Allum Chine a bed of gravel and the overlying brick-earth have been cut away by the older valley, on the side of which lies a bed of white gravel, overlapping the edges of the brick-earth and the lower gravel. The chine itself has cut through the white gravel.

Towards the entrance of the Solent the coast-line trends seaward,and the tableland is prolonged to a lower level. Inside Hurst Castle, where the coast is sheltered from the open sea, the gravel plain falls with a gradual slope almost to high-water level (Section No. 5). This is the case all along the shore of the Solent to Eaglehurst, at which point the coast is exposed to the open sea from the direction of Spithead, and has been cut back, and the cliff is consequently higher. At the lower level the country here does not present the same tabular character; from the 100-feet level downwards, the fall appears to be more by steps, and the surface has, moreover, been a good deal modified by the streams.

The plains of Boldre and Beaulieu Heath present the tabular character before described, and rise gradually to an escarpment, which is 140 feet above the sea towards Brockenhurst, and 120 feet near Southampton Water. Northward of the escarpment the general surface of the country is 80 or 100 feet lower, much intersected by the tributary streams of the Beaulieu river, and generally covered by a wash of gravelly loam; but detached gravel-topped hills rise in the lower ground to levels corresponding to the plains, and are evidences of the former extension of the tableland beyond its present northern edge.

The Boldre river, and the Exe or Beaulieu river, flow in well-defined valleys through the tableland, as is shown in section No. 2, which crosses the river-valleys at right angles. In section No. 5, which is nearly parallel to the Boldre river, the bottom of the valley is shown by a dotted line. The fall of the valley is only 4 feet per mile, while that of the tableland adjoining is about 20 feet per mile.

(b.) The tableland of Beaulieu Heath abuts boldly upon the western shore of Southampton Water, as section No. 2 shows; but on the opposite or Netley side of the water there is a low gravel-capped cliff, 10 or 20 feet above the sea-level, from which the ground rises at first rather sharply to 60 feet, and then gradually to an escarpment from 200 to 300 feet high, overlooking ground to the north-eastward 140 or 160 feet lower in level (sections Nos. 2 and 6). This escarpment extends from Chilworth, by Bitterne, Bursledon Mill, and Sarisbury Green, to the Titchfield river. It varies in height from 304 feet at Chilworth, to 150 feet near Titchfield, and is roughly parallel to Southampton Water and the coast-line. The surface is very generally covered with gravel or brick-earth, except where it has been removed by fluviatile action; and the rivers Itchen and Hamble and the Titchfield river cut through the tableland exactly as the Boldre and Beaulieu rivers do on their way to the Solent, so that Southampton Water bears the same relation to the former rivers as the Solent does to the latter. The bottom of the Itchen valley is shown in section No. 6 through Southampton to Chilworth and Chandler's Ford. About Shirley, Chilworth, and Toot Hill the carving out of deep valleys in sloping tableland is as remarkable as near Bramshaw telegraph.

The river Test, which is by far the most considerable of the rivers flowing into Southampton Water, is bordered on the west, near Romsey, by high ground covered with gravel, which, near Shootash, attains a height of 275 feet above the sea, or 240 feet above the Test valley. From Shootash a gravel-covered crest runs northwards for two miles, having low ground on the west and a gradual slope towards the river; and high land covered with gravel extends for three miles to the south of Shootash, at an elevation of upwards of 140 feet above the valley.

At Cadbury Farm, one mile north-east of Mottisfont and five miles above Romsey, is a patch of gravel 15 feet thick, about 270 feet above the sea, and nearly 200 feet above the river, which appears to be an outlier of the gravel just described.

On the east of the Test, opposite the high gravels of Shootash, extensive gravel-covered surfaces occur at from 80 to 100 feet above the river, between which and a lower level of gravel a well-defined step is observable. About Redbridge there are gravel flats at a low level, which, towards Southampton, appear to join the sheet of gravel which covers the sloping tableland, and extends up to the escarpment.

Bordering on the Itchen, between Bishopstoke and Swathling, is a great bed of gravel at about 20 feet above the river. Lower down the river, where it traverses the high ground, there are gravels at the same level, cut off from the gravel covering the plain by a bare slope. Near the confluence of the river with Southampton Water the gravel covering the tableland and the valley-gravel of the Itchen appear to join.

To the east of the Hamble river the tableland of Titchfield commonis separated from the lower ground of Chilling and Brunage by a tolerably well-defined step, which extends beyond the Titchfield river, and is shown in section No. 7 from Brunage and section No. 8 from Stubbington, northwards. Titchfield common and the tableland about it is gravel-covered; but this appears not to be the case with the corresponding level between Titchfield and Fareham. The lower level of Brunage, Hill Head, Stubbington, and Alverstoke is almost uniformly covered with gravel or brick-earth. The section which is seen in the cliff between Hook and Browndown has been well described by Mr. Evans^[6]; the cliff is everywhere less than 40 feet above the mean sea-level, and the gravel in several places reaches as low as high-water mark.

From Browndown a low inland cliff, which rises above the shingle of the rifle-ranges, runs inside the fortification-ditch as far as the railway at Anglesea, and marks the boundary of the gravel which covers the level of Lee, Grange, and Alverstoke. Between this cliff and the shore lies a level tract more than three miles long and a quarter of a mile wide, and but little above high water. The structure of the shingle composing it was exposed in extensive excavations made to obtain materials for the concrete blocks for the Spithead forts. It is evidently a recent beach-deposit due to existing conditions. It has not the coherence or the ferruginous colour of the gravel in the cliffs of Brunage and Lee, from which it also differs in containing numerous oyster and other shells; but the materials are the same, flints but little rolled, with frequent seams of sand, and in general structure there is a good deal of similarity.

About Portsmouth a low gravel-covered flat, which is apparently a continuation of that on the Gosport side of the harbour, extends to the base of the chalk range of Portsdown Hill, to the east of which the lower level is again divided from a higher gravel-covered surface 140 feet above the sea by a slope. Section No. 9 through Hayling Island, and passing half a mile to the west of Bourne Common, to which point the westward extension of the Brighton beach has been traced by Mr. Prestwich^[7], shows a very similar outline to the sections near Titchfield (Nos. 7 & 8). Still further eastward are the remains of the old sea-bed at Avisford and Waterbeach^[8] with marine shells at from 80 to 100 feet above the sea-level, to the south of which lies the low ground of Selsea, covered with marine gravel containing large blocks of syenite, porphyry, granite, &c. and overlying the mud-deposit of Pagham^[9], which contains littoral shells of southern species, with remains of Elephas antiquus^[10].

(c) The gravel varies but little in character or composition over the area which has now been described; it consists almost exclusively of chalk flints, little rolled and often perfectly fresh. There is always, however, a proportion of tertiary pebbles; and where, as between Bournemouth and Christchurch, extensive pebble-beds occur in the underlying tertiary strata, the proportion of pebbles in the gravel is considerable. Fragments of sarsen, or grey-wether sandstone, are met with everywhere, and blocks of considerable size are found in the gravel of the cliffs between Southampton Water and Gosport, and near Southampton, at 170 feet above the sea. A block of puddingstone, part of a larger mass, which is stated to have come from the gravel of Hordwell Cliff, is now in the Jermyn-Street Museum. Mr. Godwin-Austen^[11] has recorded the presence of waterworn specimens of white quartz, granite, and porphyry in the gravel on the high plain a little to the east of Poole, at about 160 feet above the sea; and white quartz-pebbles certainly occur as far east as Lymington. In the gravel covering Portsea Island, at a level not much above high water, numerous blocks of granite, syenite, and greenstone, as well as of sarsen-stone, are found. They are to be seen lying in the gravel-pits near Southsea, where the gravel is at least 27 feet thick, and covered with brick-earth, and in the excavation for the sewers they were frequently met with. They are rounded and smoothed boulders, from 1 to 2 cubic feet in size, and have undergone a partial decomposition, which renders them brittle. They do not appear to extend to the gravel on the west of Gosport, which is but little higher in level. They are probably derived from the same source as the similar boulders of Pagham and Bracklesham, namely, from rocks on the French side of the channel.

Brick-earth of a sandy nature is generally interstratified in the gravel in lenticular seams, and sometimes overlies it. The bedding is generally even and free from disturbance or contortion; and it is to be remarked that the contortions and foldings of the brick-earth and gravel usually attributed to glacial action are met with only at comparatively low levels. In the low gravel-cliffs to the south of Christchurch, near Brunage, and in a gravel-pit near Anglesea (Pl. XXXVII. fig. 14) the characteristic convolutions are seen; but the height at these places is not more than 30 feet above the sea.

At heights ranging to 200 and 300 feet above the sea, the gravel is sometimes folded, apparently from the unequal wasting and subsidence of the clay or marl on which it lies. There is an instance of this near Chilworth "Tower of the Winds," at 300 feet above the sea, where the Bracklesham clay has so wasted and subsided (fig. 15). This action is more commonly observable at the edges of the plains, and in some cases from this cause the bedding of the gravel has been entirely effaced.

The general colour of the gravel is a deep red-brown; there is, however, a white gravel (so known locally and distinguished from the red or binding gravel) which is often met with and deserves some notice. It generally overlies the red gravel and penetrates it in potholes and pipes. It is loose and sandy, and the flints in it are white, with a curious porcelain-like lustre. The sandy matrix is sometimes dark with vegetable matter, and there is often a black carbonaceous band between the white gravel and the red (vide fig. 15). I believe that generally the white gravel has been formed in situ, and that its origin is due to the bleaching-action of water holding organic matters in solution upon the red peroxide of iron, by reducing it to a soluble protoxide in the way pointed out by Bischoff^[12]. The pipes of white gravel penetrating the red, and the black carbonaceous band separating the two gravels, are usually full of root-fibres. Where, as in some sections, the white gravel seems to be interstratified in the red, it is probable that an unseen pipe communicates with a more sandy and porous seam, which has been bleached, while the less porous gravel over it has been unaffected. In some instances, however, it appears as if the white gravel were a subsequent deposit. In a section in a brick-yard to the east of Lymington the red gravel seems to have been cut away before the white was deposited on its flank. In the chines or bunnies to the west of Bournemouth there are sections at right angles to the coast showing the reel gravel with brick-earth over it, ending against a slope of Bagshot sand on the land side and thinning out towards the sea, so that the white gravel which overlies both overlaps the brick-earth, and rests directly on the red gravel, reduced to less than half its thickness in the sea face of the cliff. In the east side of Allum Chine the white gravel is seen overlappingboth brick-earth and red gravel, and resting directly on the Bagshot sand. These appearances are not, however, inconsistent with the supposition that the white gravel is contemporaneous with the red, and has been bleached in the way above noticed in consequence of its porosity.

The occurrence of white gravel over red in the south-west of Sussex is noticed by Mr. Martin^[13], and by Mr. Godwin-Austen^[14], both gentlemen considering the white gravel to be the newer, and a distinct deposit from the red gravel.

The gravel varies much in thickness. On the plains at high levels sections are rare, but the depth does not generally appear to exceed 5 or 6 feet. On the edges of the plains bordering on the valleys, and on the terraces which occur, a little below the level of the plains in the larger valleys, the thickness is greater. In the railway-cutting one mile south of Wimborne, through a plain 176 feet above the sea, the gravel is as thick as from 25 to 30 feet. Where the junction of the gravel with the underlying formation is exposed in long sections, it is seen to be much more irregular than the surface. There are instances of this in the railway-cutting hear Wimborne, and in that through the level plain between Christchurch and Bournemouth, where the gravel varies from 2 to 12 feet in thickness in 20 yards. In the cliff-sections similar variations are observable; but the average thickness in them and in the gravel-pits in the neighbourhood is about 10 feet. In the Barton and Hordwell Cliffs the gravel is 15 or 18 feet thick, but it thins out, as before noticed, to 8 or 9 feet in pits near the coast, and to 5 or 6 feet more inland. On the plains about Beaulieu, and on the eastern side of Southampton Water, 6 or 7 feet appears to be the average thickness, while at low levels, as in the cliff-section between Southampton Water and Gosport, it is generally 10 feet, and sometimes 15 or 16 feet, and in a pit near Southsea at least 27 feet thick, extending to below the sea-level.

(d) No organic remains have hitherto been found in the gravel covering the plains. Mr. Trimmer, who carefully examined the New Forest and the neighbouring country, observes that he found neither shells nor mammalian bones, nor could he hear of any having been found in the gravel^[15]. Mr. Wise, in a recent work on the New Forest^[16], notices the same absence of mammalian remains. He records the finding of the os innominatum of probably Bos longifrons; but the locality was Shepherd's Gutter, near Bramshaw, on low ground, and in gravel perfectly distinct from that covering the plains. In the valley-gravels mammalian bones &c. have been found. The rich collections made from the gravels of the Avon and Wily, near Salisbury, are well known. At Fordingbridge, ten miles below Salisbury, on the Avon, the teeth of Elephas primigenius have been found in gravel about 40 feet above the river, in which also were imbedded several flint implements now in the Blackmore Museum at Salisbury.

In gravels of the Stour valley near Blandford, 50 feet above the river, elephant- and horse-bones and teeth were found in some abundance^[17].

At Dewlish, situated on a tributary of the Trent or Piddle, which flows into Poole Harbour, the bones, molars, and tusks of Elephas meridionalis were found in 1813 in a pit on the side of a chalk hill 100 feet above the base. A molar is preserved in the Blackmore Museum, in the guide to which^[18] Mr. E. T. Stevens quotes the notice of the discovery given in the 'Monthly Magazine' for May 1814.

At Swathling, near Southampton, in the valley of the Itchen, a molar of Elephas primigenius was discovered a few years since in gravel about 10 feet above the river, and is preserved at the Fleming Arms Inn.

Flint implements have been found in the tabular bed of gravel capping the cliffs near Bournemouth at 120 feet above the sea-level; of these, one or two were found in situ by Dr. Blackmore. In the Christy collection is a cast of a large oval implement from near Lymington; and recently two specimens have been obtained from gravel-pits on Southampton Common at 86 and 150 feet above the sea-level. From the gravel cliff between Southampton Water and Gosport numerous specimens have been obtained. With one exception these were picked up on the beach, on which they evidently had been rolled; but the sharp angles appear to have been smoothly rounded off before the rougher rolling on the modern beach took place. With few exceptions they have the whitish coating and porcelain-like lustre of the flints in the white gravel already described; and as the white coating has been removed at the angles by the beach-rolling, it would seem that the implements are derived from the white gravel. At Bournemouth also they are generally white, so that it would appear that on the Hampshire coast the implements lie near the top of the gravel, and not, as is generally the case, near the base.

 

III. The Isle of Wight.

The general features of the Isle of Wight are well known. A chalk range running east and west, and attaining an elevation of nearly 700 feet, divides the island into two nearly equal parts, and is traversed by three river-valleys, at Freshwater, at Newport, and at Brading. More than three quarters of the island is drained by the rivers thus flowing northward to the Solent and Spithead.

(a) In the northern part of the island the flat-topped hills are capped with flint-gravel at from 100 to 300 feet above the sea; and though the evidences of a once continuous gravel-covered tableland are not so plain as on the mainland, section No. 10, from St. George's Down to Norris, shows how the gravel covering the hills coincides with a plain having a uniform slope towards the north. Detached patches of similar gravel on Hempstead Cliff, 200 feet, and on Headon Hill, 390 feet above the sea, may also be looked upon as remnants of a tableland comparable to that on the mainland, but sloping northwards.

The gravel differs but little from that on the mainland. It contains, however, besides chalk-flints and tertiary pebbles, Upper-Greensand chert and materials from the Lower-Greensand beds. In the gravel on the cliff near Egypt, to the west of Cowes, at about 130 feet above the sea, I found a large liver-coloured pebble evidently derived from the New Bed Conglomerate beds. This, with the white quartz and granitic pebbles already noticed as occurring in the gravel at Lymington and on Poole Heath, establishes a connexion with country far to the westward, which is worthy of notice.

As on the mainland, neither shells nor bones of any sort have been found in this gravel, though the valley-gravels have afforded mammalian remains in some abundance; Mr. E. P. Wilkins, of Newport, records^[19] the discovery in the gravels of the Medina valley of teeth and bones of the mammoth, rhinoceros, horse, ox, deer, and hog.

(b) To the south of the chalk range there are gravels which, though lying at considerable elevations, do not appear to be fragments of a tabular surface, but rather to be high-level gravels connected with the rivers which drain the southern part of the island, and flow northward through the chalk range. Such is the gravel on Blakedown, 270 feet above the sea and 170 feet above the adjacent stream, and that at Whitcomb, 260 feet above the sea and 160 feet above the stream.

With them may be also classed the deposit of gravel and loam which caps the cliffs between Blackgang Chine and Compton Bay. Near the former place it attains a height of 300 feet above the sea, and undulating with the cliff- section, it falls as low as 50 feet opposite Compton Grange, rising again to 100 feet to the west of this, where the gravel thins out; but the overlying brick-earth is continued for some distance further. The gravel consists of flints, with chert and ironstone; it contains sand-seams, and is overlain by evenly bedded brick-earth. To the east of Brook Chine the gravel is as much as 15 feet thick, and the brick-earth 12 feet.

At two points in this deposit, at about 100 yards east of Grange Chine, between 60 and 70 feet above the sea, and at half a mile east of Brook Chine, and about 96 feet above the sea, Mr. Wilkins informs me that remains of Elephas primigenius have been found. In both cases they were from the gravel continuously capping the cliff, and not in valleys connected with the Chines.

At a small Chine called Sheppard's Chine, a mile west of Brook, are the peaty beds with hazel-nuts and twigs, which have been often described as lying beneath the gravel^[20]. In August, 1868, it was plain that these beds were in a hollow in the gravel, which was 2 feet 6 inches thick beneath them. Over the seams of sand containing vegetable matter lies 5 feet of sandy brick-earth.

(c) Within two miles of the western end of the deposit which caps the cliff continuously from Blackgang Chine, are the mammaliferous gravels of Freshwater, which were described by Mr. Godwin-Austen in Forbes' s Memoir; and his description in 1853 corresponds well with the section now exposed. The lower beds contain subangular chalk-flints, with much lower cretaceous ironstone and chert, and bands of coarse sand, the whole stained of a red-brown colour. These beds rest on the chalk, and against a rearranged formation of chalk-flints in a chalky paste, which is perhaps a talus formed by subaërial weathering of the chalk before the deposition of the gravel. A curved line sloping steeply towards the valley separates the lowest beds from a similar gravel of a lighter colour, which is not always to be clearly distinguished from the former. A third gravel is again sharply divided from the second by a curved line sloping towards the valley. It is finer, more sandy, with much cross bedding, and contains many small white chalk-pebbles; and it was in this that the molar of Elephas primigenius, now preserved at the Albion Hotel, was found at a few feet above high-water level. Over all the gravel- deposits lies a stratum of brick-earth from 4 to 13 feet thick, containing seams of angular fragments of flint, which reaches a height of about 60 feet above the sea towards the Fort. On the east side of the valley another molar of Elephas primigenius was found in the gravel, and there are many shells of Succinea and Pupa in the overlying brick-earth.

(d) There is here exhibited in a sea-cliff a complete section across a river-valley with its gravels ; and the direction in which the river flowed was clearly from the southward, and seaward. The presumption would be strong that the river flowed in the same direction as the present stream, were there no evidence in the materials of the gravel to show that the river ran through the Lower Greensand and Wealden beds. In considering what extent of land existed to the southward of the present coast-line when these gravels were formed, a comparison with the very similar valley at the eastern end of the island gives indications worth notice. At Freshwater a stream rises close to the beach, at a level below that of high water, and flows northward to the Solent, by Yarmouth. At the other end of the island the Brading river has two branches, one rising at the back of a beach protected by groynes, in Sandown Bay, and flowing for its entire course below the level of high water; and the other draining a considerable area towards Arreton and Niton.

Mr. Godwin-Austen has observed^[21] with regard to the Sandham level, which constitutes that part of the valley of the Brading river which is below high-water level, that excavations for deep drains show no signs of estuary deposits, or evidence of the sea having formerly occupied it; and the same observation applies to the Freshwater valley. Not only is there no evidence that the sea has ever occupied these valleys, now not much above half-tide level and artificially protected from the sea, but the succession of gravels down to the sea-level seems to prove that both valleys have been gradually deepened by fluviatile action only.

Both valleys traverse the chalk under similar circumstances; the thickness is the same, and the strata are nearly vertical. Fig. 13 (Pl. XXXVII) shows the transverse sections of the two valleys through the chalk drawn to the same scale, and if the sectional areas may be considered as roughly proportional to the extent of the river-basins, the ancient Yar was at least as important a stream as the Brading river. The latter at present drains 24 square miles, to the south of the chalk range, or 1/6 of the area of the island; and gravels on the cliffs about Sandown show that the branch of the river which now rises near the beach is the representative of a much larger stream, which, when flowing 100 feet higher, drained land then occupying the position of Sandown Bay. It is therefore not an improbable supposition that the gravel with Elephant remains on the cliffs at Brook and Grange was included in the same river-basin as the Freshwater gravel, and that the streams now entering the sea between Blackgang Chine and Compton Bay were tributaries of a river flowing northwards through the chalk range to the Solent. The difference of level in the gravel is no more than is due to the natural fall of the watercourses, and the waste of the cliffs now going on shows that a considerable area of land has but recently been destroyed.

The chines by which the streams at the back of the Isle of Wight enter the sea are probably due to the alteration in the drainage consequent on the destruction of this land. The streams ending in chines present no unusual features until they come within a short distance of the coast, when they begin to fall more and more rapidly through a ravine, which has been cut out in the bottom of a valley corresponding in level and cross section, and continuous with that in which the stream flows before it enters the ravine. The increased rate of fall towards the sea is opposed to the general tendency of streams to fall less as they near their outfall, and it seems to point to a somewhat sudden change in the conditions under which the streams flowed. Such a change would result if the streams which were tributaries of a river flowing to the Solent by Freshwater had been provided with new outfalls by the cutting back of the coastline, until the river and its branches were intersected while still flowing at a considerable height above the sea. If this be the true explanation of the occurrence of the chines at the back of the Isle of Wight, it would seem to be a fair inference that where chines, or bunnies, are found, a similar change in the outfall of the streams has taken place.

(e) The section of gravel exhibited in the cliff round Foreland Point, at the eastern extremity of the Isle of Wight, seems to deserve a more detailed description than it has hitherto received, although it has been often mentioned^[22] in notices of the superficial deposits of the neighbouring country.

Fig. 12 (Pl. XXXVII.) represents the section exposed in the coastline from Whitecliff Bay, round the headland. The main mass of gravel consists of rounded chalk-flints, imbedded in sand and distinctly stratified in layers of pebbles of assorted sizes, dipping slightly northward. The flints, though well rounded, have not the finish of the pebbles in tertiary pebble-beds, and the structure shows it to be a beach-deposit. Seams of pure sand overlie bands of pebbles as large as oranges, and layers of pebbles stained a dark red are succeeded sharply by bands of white pebbles. Pieces of sandstone, and fragments of chert and sandstone from beds below the chalk, are occasionally met with. The thickness is between 30 and 40 feet, extending from a few feet above high-water mark to 60 feet above the mean sea-level. The general colour is a red-brown, and it is only near the overlying brick-earth that there is any admixture of clay or loam.

No organic remains of any sort have been found in this gravel. In structure it is exactly like a beach-deposit, and in many respects unlike the gravel covering the high ground of the north of the island and the mainland.

Gravel of a similar character is said, by Mr. Godwin-Austen^[23], to occur at St. Helens, and is supposed by that gentleman to be a continuation of the Foreland bed. A deposit of gravel on the shore to the east of Ryde is described by Mr. Bristow^[24] as consisting of "white rounded flint-pebbles in brown clay, precisely similar to those found on a modern sea-beach." A somewhat similar gravel of rounded flints of considerable size is also noticed by Mr. Bristow as occurring in the valley of King's quay, between Ryde and Cowes.

The mass of shingle-gravel at the Foreland thins suddenly towards the south, and is overlain by 36 feet of brick-earth containing a few seams of small angular flints, which thins rather abruptly to 6 or 8 feet, and caps the edges of the Eocene beds nearly to the chalk range, reaching a height of 100 feet above the sea. A similar brick-earth, with more or less of angular flints, appears at heights up to 100 feet at many points over the Bembridge peninsula. At a point marked on the section (fig. 12), in the brick-earth a little to the south of the thick mass, I found a flint implement of the oval type. It lay within a few feet of the top of the cliff, or rather of the broken slope of marl, which at that point reaches 85 feet above the mean sea-level. It was with a few other flints which had recently become detached from the brick-earth, of which the implement still bore traces. Unlike the great majority of those from the gravel of the Hampshire coast, it is perfectly sharp in the angles of the chippings.

The brick-earth, where it thins out over the thick mass of shingle-gravel, is eroded and overlain by a drab-coloured loam, which caps the shingle-gravel throughout, and extends partly over the other deposits to be noticed further on. A little to the north of the Coast-Guard Station, where the cliff loses height, the deep red-brown shingle- gravel is overlain by a white shingle, the junction being slightly irregular, and dipping about 3° northwards. In a short distance a peat-bed appears beneath a more clayey gravel, which takes the place of the white shingle; just beyond, a bed of brick-earth is interstratified in the gravel, and about a quarter of a mile from the first peat-bed another and larger one occurs. The two deposits are so much alike in character and situation, as to render it probable that the same bed is seen at two points. At a few feet above highwater mark the Bembridge marl is covered by a few inches of dark grey clay with black pebbles, on which the peat-bed lies, and is covered by 6 inches of grey clay, succeeded by a red clayey sand passing up into a clayey pebbly gravel. The peat-bed does not much exceed a foot in thickness; it is described by Mr. Godwin-Austen, who examined it with Professor E. Forbes, as having the usual characteristics of accumulations of vegetable matter in damp situations, and containing the remains of large trees, hazel-nuts, and beetles^[25]. The top of the cliff where the peat-beds are is less than 25 feet above the mean sea-level, and the gravel is much more clayey than the pebble-gravel proper, and confused in the bedding. Beyond the second peat-bed, towards Bembridge, the cliff again rises, and the gravel is again evenly stratified clean shingle.

In this section the shingle-gravel is clearly the oldest, and at the time of its accumulation the highest part must have been near the sea-level. It may with probability be looked upon as the equivalent of the Brighton. Beach, the extension of which has been traced westwards by Mr. Prestwich^[26] to Avisford, Goodwood, and Bourne Common, fourteen and a half miles to the N.N.E. of the Foreland gravel^[27]. The brick-earth corresponds in position with the rubble-bed with elephant remains over the old beach at Brighton, and with the similar bed with land shells over the Sangatte beach. The main mass appears to fill up an old channel cut through the shingle, and its highest part could hardly have been deposited much above the level of the sea, which, as the shingle shows, must have been near. A rise of land to the extent of 70 or 80 feet appears, therefore, to have taken place since the deposition of the brick-earth in which the flint implement was imbedded. The peat-beds, and the gravel and brick-earth over them, must have been formed at or above their present level and subsequent to the upheaval.

 

IV. General Considerations.

In entering upon the consideration of the conditions under which the gravels of the district now under notice were deposited, it will be convenient to take as a starting-point the great gravel-covered flat of southern Sussex. The marine character of this gravel has been shown by Mr. Dixon^[28], Mr. Godwin-Austen^[29], and others. At Pagham, Bracklesham, and Selsea it overlies the mud-deposit with shells of southern species (Pecten polymorphus &c.) and the remains of Elephas antiquus, and contains ice-transported boulders of granite, porphyry, syenite, and palæozoic rocks. The gravel covering Portsea Island is the same in level, and also contains similar boulders. Passing across Portsmouth Harbour, the gravel between Gosport and Southampton Water lies at the same level, and is apparently a continuation of the others. It presents, however, a more fluviatile appearance, and large blocks of sarsen-stone brought down from inland, and lying in contorted gravel, take the place of the granitic boulders of Selsea and Portsea, and are equally indicative of the glacial conditions under which the beds were deposited.

To the northward of this low tract lie the beach-deposits described by Mr. Prestwich^[30], containing marine shells at from 80 to 100 feet above the sea-level at Waterbeach, near Goodwood, and extending westward to Bourne Common; the high ground, with gravel, shown in section No. 9; and, passing by Portsdown Hill, which rises immediately from the low ground, the corresponding level shown in sections Nos. 8 and 7, separated from the lower tract by a steeper slope or step.

The old sea-bed of the Sussex level, then, appears to pass between the old coast-line thus marked out on the north, and the beach-deposits of the Foreland, St. Helens, &c. along the coast of the Isle of Wight, becoming more like a river-gravel in character, and containing numerousflint implements in its westward extension. The supposition that there was here an estuary through which the rivers from the westward reached the sea when the Isle of Wight was still joined to the mainland, derives support from other considerations.

(a) The connexion of the island with the mainland, which is obviously suggested by the continuation of the chalk range of Purbeck through the island, appears to have existed down to recent times. The ten-fathom line, which is within half a mile of the coast all along the back of the Isle of Wight, strikes across Christchurch and Poole Bays to Handfast Point, following the course of the vertical chalk strata, and again hugs the shore round the Purbeck coast. Inside this line the sea is generally less than five fathoms deep, and is steadily encroaching on the land at the rate of about a yard in a year. At this rate the coast would have receded from the line of the chalk to its present position in about 9000 years. This is of course but a rough estimate of time, but it shows the probability of a connexion by which the Mammoth and tichorhine Rhinoceros had free access to the Isle of Wight down to the time of the lower valley-gravels, in which their remains are far from rare.

The Chines, or bunnies, along the coast between Hordwell and Poole appear to show that a change has taken place in the course by which the streams reached the sea, as has been already pointed out. The extensive mud-flats more than a mile wide along the north shore of the Solent must, as Mr. Godwin-Austen has observed^[31], have originated in a very different condition of the Solent from the present, and they also point to the comparatively recent time at which the condition was that of an estuary, in which the formation of such mud-flats would have been natural.

When a continuous range of chalk downs stretched along where the ten-fathom line now lies between the Needles and Handfast Point, the river system was most probably analogous to that which now exists. All the streams which traverse the chalk of the Isle of Wight and Purbeck, flow northwards from the older beds into the Tertiary basin; and it appears unlikely that the rivers which now enter the sea at Poole and Christchurch took an opposite course through the chalk. It is natural to suppose therefore that the Frome and Piddle continued their easterly course inside the chalk range in a joint stream, of which the Avon and Stour were affluents, and which received tributaries draining country up to, and perhaps beyond, the chalk on the south, as the Corfe River, the Medina, and the Brading river still do. The rivers flowing into Southampton Water joined those coming from the westward by way of the Solent, and formed a broad estuary communicating with the sea by Spithead.

(b) Mr. Prestwich has correlated^[32] the Brighton beach and the Sussex gravel-beds with the estuarine beds of Menchecourt, and has also remarked^[33] on the close resemblance which the Menchecourt beds bear, marine characters apart, to those at Fisherton, near Salisbury. The flint implements from the coast between Gosport and Southampton Water bear a corresponding resemblance to those from Fisherton and from Menchecourt. The ovoid type greatly predominates; and where, as at the Blackmore Museum, a large number of implements from the Hill Head gravels can be compared with a series from Fisherton, and from Milford Hill, near Salisbury, the general resemblance of the Hill Head and Fisherton specimens to each other and to the Menchecourt type, and the different character of the Milford Hill implements, and their resemblance to the spear-head form common at St. Acheul, are equally manifest. Adopting the supposition that the Avon flowed to the sea by Spithead, it is not difficult to trace a connexion between the Sussex and the Hill-Head gravels and the Fisherton beds. The gravel bordering on the north shore of the Solent carries on the Hill-Head gravel to Lymington, where an oval flint implement has been obtained from it, and on to Milford. Beyond this the coast is exposed to the open sea, and has been cut back, so that none of the lower level remains until the Avon valley is reached, six miles to the westward. There contorted gravel and brick-earth are seen in the cliff-section of the old river channel beyond Hengistbury Head, at from 20 to 40 feet above the sea-level, and thence the connexion of the valley-gravels up to Salisbury is plain. The plateau of Beaulieu Heath, which is about 70 feet above the lower gravel on the north of the Solent, and which corresponds in level and position to Titchfield common, stretches continuously to Poole, broken only by the river-valleys, as is shown in section No. 2. In the gravel covering of this tableland the flint implements of Bournemouth are imbedded, and it seems probable that the gravel of the plains at this level near the coast may correspond in age with the high-level valley-gravels, as it does in position with regard to the lower valley-gravels.

Having thus a sort of datum-line with which to compare the levels of the gravel covering the plains, it appears that while near the coast the tableland is but 50 or 60 feet above the lower valley-gravels of the Avon, at Fordingbridge it is 250 feet higher than beds with flint implements and Elephas primigenius, which lie about 40 feet above the river; and when the tableland attains its greatest elevation near Bramshaw Telegraph, it is 240 feet above the Fisherton beds in actual level, or if the plain were prolonged at the same inclination it would pass 400 feet above the Fisherton beds, and 320 feet above the top of Milford Hill at Salisbury.

It is remarkable that the inclination of this tableland, if prolonged still further, is found to touch the highest points of the country up to the source of the Avon; namely, Dean Hill, and Beacon Hill, Milk Hill, and Martinsell on the north of the vale of Pewsey.

An argument for the great antiquity of the gravel of Milford Hill, at Salisbury, with its imbedded implements, has been justly based on the circumstance that since it was deposited the valley of the Avon has been deepened some 80 feet, and that after by far the greater part of this deepening had been accomplished, the Mammoth, Rhinoceros, Lion, Hyæna, Marmot, Lemming, &c. left their remains in the Fisherton beds. The same line of reasoning shows the far greater antiquity of the gravel on the higher plains of the New Forest, of that on both sides of the Itchen, near Southampton, and near Newport, in the Isle of Wight, more than 250 feet above neighbouring valley-gravels containing Elephas primigenius, &c.

(c) But if the great height attained by the gravel-covered plains is evidence of an antiquity far greater than that of the Milford Hill, and other high-level valley-gravels, the uniform surface of the tableland points to a continuance of similar conditions from the time of deposit of the highest gravels down to that of the gravel containing flint implements at Bournemouth, Lymington, Hill Head, &c. What these conditions were is open to question; there are no organic remains by which to decide whether the gravel covering these wide plains is an extension of the gravels of the neighbouring rivers, or a marine deposit, like that covering the southern part of Sussex.

It has already been pointed out that, probably down to the time of the low-level valley-gravels, the Isle of Wight was connected with the mainland, and a river, comprising in its drainage-area the basins of the rivers now reaching the sea at Poole, at Christchurch, and by Southampton Water, flowed by Spithead to the sea. Fig. 11 is a map of the catchment basins of the rivers in question^[34]. The area drained by all the rivers entering the sea from Poole to Portsmouth, together with the Isle of Wight, and Christchurch and Poole Bays, out to the 10-fathom line, is 2750 square miles, equal to 3/4 the area of the basin of the Thames above Hampton. Of this area, 666 square miles, or nearly 1/4, is comprised in the basin of the Avon, 544 square miles in that of the Test, and 479 in that of the Stour; while only 331 square miles, or less than 1/8, is drained by the rivers entering Poole Harbour. The hydrographical area of the old river appears therefore to have been comparatively small, and but little augmented by the western river-basins. Within it, however, lie the large gravel-covered surfaces which have been described. Of these the New- Forest tableland alone slopes in the direction of the principal lines of drainage; it occupies the watershed between the Avon and the Test, and falls in the direction of their flow at the rate of from 18 to 34 feet per mile. The tableland on the east of Southampton Water slopes at the rate of from 30 to 120 feet per mile towards the water, and the Isle of Wight tableland at from 30 to 40 feet per mile northward. The flattest of these inclinations, that of the New-Forest tableland, is, for the course of a river, very great, and such as only mountain-streams have^[35]. It is difficult to conceive that a river flowing with the velocity due to such a fall could have spread out the gravel over these wide even surfaces more than 20 miles across; and the various directions in which the tablelands slope forbid the supposition that any part of the present inclination is owing to a subsequent tilting up of the land.

It is perhaps a more probable hypothesis that the spreading out of the gravel and the levelling of the plains took place in an inlet shut in on the south by high land and opening out to the eastward. If this were the case, the land at the time of the deposition of the highest gravels now remaining must have stood 420 feet lower; and this may have been in some degree contemporaneous- with the great depression of the Boulder-clay epoch. A deposit thus formed of materials brought down from the chalk country on all sides would be entirely local in character; but the apparent absence of indications of glacial conditions in the gravel, except at levels so low as to correspond with valley-gravels, is not easy of explanation.

(d) The raised shingle of the Foreland, the marine gravel of the south of Sussex, and the beach-deposits with sea shells at Avisford and Waterbeach are evidences that at a time geologically recent the land stood 80 or 100 feet lower. Flint implements, however, are found imbedded in gravel 120 feet above the sea on the Bournemouth cliffs, and 150 feet above the sea on Southampton Common; and an hypothesis which assumes that man existed when gravels, now 120 and 150 feet above the sea, were forming at or below the sea-level may be on that account alone considered as untenable. But flint implements are found at Menchecourt associated with marine shells at 40 feet above the sea, and at the Foreland under circumstances which seem to show that an elevation of land to the extent of from 70 or 80 feet has taken place since man's appearance; and when it is considered what an enormous amount of change has taken place at Salisbury and elsewhere since the high-level gravels containing flint implements were deposited, and what a vast amount of time such changes imply, it does not appear to be incredible that the upheaval should have been so much as 150 feet.

A considerable alteration in the coast-line must also have taken place. Land must have existed to the south of an inlet such as that supposed, of which the Isle of Wight is but the shadow. Denudation of the surface by subaerial action, and of the coast by the sea, must have gone on pari passu with upheaval ever since the high plains were first raised above the sea-level. As the land gradually rose, the effect would have been to contract the inlet and bring it into the condition of an estuary branching into the Solent and Southampton Water. Of these, the latter remains an estuary, while the Solent has become an arm of the sea by the severance of the Isle of Wight from the mainland.

(e) The last movement appears, however, to have been one of subsidence. Submerged forests have been observed in Poole Harbour, off Bournemouth, off Southsea Castle, off Pagham, and at Portsmouth. Sir Charles Lyell ^[36] adopts the conclusion of the Bishop of Gibraltar, that the Bournemouth forest was submerged by the washing out of a sandy substratum without a general subsidence of the land, and explains the occurrence of the similar deposits on the north side of Poole Harbour in the same manner. The section at Portsmouth, which was described by Sir H. James^[37], appears, however, to afford good evidence of a downward movement. An old terrestrial surface with rooted trees which, when living, must have stood at least 30 feet higher, was exposed in the dockyard in 1847, and has been again brought to light, but at a higher level, in the works for the extension of the dockyard now in progress. The origin of Poole Harbour and Christchurch Harbour, and of Portsmouth, Langston, and Chichester Harbours, is probably in a great measure due to this subsidence, which, according to Mr. Godwin-Austen^[38], there is some reason to believe has gone on till within the last few centuries.

(f) The denudation which the surface of the country has undergone since the deposition of the gravel on the plains is as remarkable for its partial character as for its extent. Large areas of the plains at the highest levels appear to have remained quite unchanged, while close by deep valleys have been scooped out, and high escarpments have been formed by what cannot have been any other than subaërial causes, and while large tracts of land have been gradually removed by the action of the sea on the neighbouring coast-line.

The nature of the geological formation appears to have had no part in influencing the destruction or the preservation of the surface. Barton Clay, Bagshot Sand, and Headon Marls alike underlie the gravel of the New-Forest tableland, and have alike been removed over the area drained by the tributaries of the Boldre river, of which Lyndhurst is the centre. The gravel covering itself is probably the protective agent, and it may have been thinner or more loamy where the old surface has been destroyed.

 

V. Summary.

The chief points to which attention has been called in the foregoing paper are as follows:—

1. That the gravel plains of the New Forest and the neighbourhood are portions of a tableland rising slightly to the northward and attaining an elevation of 420 feet: and that the remains of similar tablelands exist on the east side of Southampton Water, and, in a more fragmentary state, in the Isle of Wight, having a slope greater and in other directions.

2. That while the gravel covering these tablelands at the highest levels is of a far greater age than the valley-gravels of the rivers, the gravel near Bournemouth, on Beaulieu Heath, Titchfield Common, and at similar levels appears to be equivalent in position and age to the high-level valley-gravels, and also to the beach-deposits of Avisford and Waterbeach containing marine shells; and that a lower tract of gravel bordering on the northern shore of the Solent and Spithead appears to correspond on the one hand with the low- level valley-gravels of the rivers, and on the other with the marine gravel covering the low land of Selsea.

3. That the spreading out of the gravel, and the levelling of the tablelands, probably was effected in an inlet of the sea shut in on the south side by land which connected the Isle of Wight with the mainland, and opening to the eastward.

4. That a gradual upheaval appears to have gone on from the time of the oldest and highest gravels down to the date of the low-level valley-gravels, by which the inlet was narrowed into an estuary which received the waters of all the rivers from Poole Harbour eastward, the Isle of Wight being still connected with the mainland.

5. That of this upheaval in its latter stages there is evidence remaining in the marine gravel of Sussex, in the raised shingle of the Foreland, and in the beach-deposits of Waterbeach and Avisford.

6. That the flint implements of Bournemouth and Southampton Common are from gravel covering tablelands at elevations corresponding to the high-level valley-gravels, and that the implements from the coast between Southampton and Gosport are from gravel corresponding to the low-level valley-gravels.

7. That the position of the flint implement found above the raised shingle of the Foreland appears to prove that an upheaval to the extent of 70 or 80 feet has taken place since its deposition in the brick-earth; and that if the origin of the gravel covering the plains be as above supposed, the flint implements of Bournemouth show that the upheaval has been as much as 120 feet, and the implements in the gravel on Southampton Common as much as 150 feet, since the appearance of man.

 

DESCRIPTION OF PLATES XXXVI. & XXXVII.

Plate XXXVI.

Map of the south of Hampshire and the Isle of Wight, with parts of Sussex and Dorsetshire, showing the principal gravel-covered surfaces. The lines of the Section are shown, and the letters refer to corresponding letters on the sections, figs. 1 to 10, Plate XXXVII.

Plate XXXVII.

Fig. 1. Section across the valley of the Avon and the highest part of the New-Forest tableland, through Fordingbridge, Hampton Ridge, and Blackbush Plain, with a section branching at Hampton Ridge and crossing the valley of the Avon at Breamore.

Fig. 2. Section near the coast between Poole Harbour and Christchurch, and following the line of strike of the New-Forest tableland to Southampton Water at Cadland. The continuation of this section on the east of Southampton Water is in the direction of the rise of the surface, and, with figs. 6 and 7, shows the slope of the tableland towards Southampton Water.

Fig. 3. Section from the coast half a mile east of Highcliff to Winckton Post, and continued from a point on the plain 1 mile to the east, to Burley Beacon, where a short branch diverges to Picked Post. The main section again divides at Bratley Plain, the western line crosses two bottoms to Leadenhall and intersects the northern escarpment of the New-Forest tableland, half a mile west of Bramshaw Telegraph. The eastern line traverses Ocknell Plain and Blackbush Plain, and cuts the escarpment 1 mile west of Bramshaw Church. This and the two following sections are in the direction of the rise of the New-Forest tableland.

Fig. 4. Section along two lines from Barton cliff, and from Hordwell cliff to Wilverley, and thence through low ground to the tableland near Stoney Cross.

Fig. 5. Section from the Solent, 2 miles east of Lymington, across Boldre Heath to the escarpment at Ladycross Lodge, and on to Matley Heath. This section shows the prolongation of the tableland down nearly to the sea-level along the Solent, and also the occurrence of detached gravel- topped hills beyond the escarpment.

Fig. 6. Section through Southampton along the Winchester road to Chandler's Ford, with a branch over Chilworth common to the escarpment near the "Tower of the Winds," the highest point of the tableland on the east of Southampton Water.

Fig. 7. Section from the coast between Brunage and Hill Head, and

Fig. 8. Section from 11/2 mile east of Hill Head northwards, show the relation of the gravel from which flint implements have been obtained with the gravel on the higher level of Titchfield Common.

Fig. 9. Section through Hayling Island northwards to a gravel-covered surface half a mile west of Bourne Common.

Fig. 10. Section through St. George's Down and Stapler's Heath to Osborne and Norris, showing the coincidence of the gravel-capped hills in the Isle of Wight, with a slope northwards corresponding to the slope southwards on the mainland.

Fig. 11. Map showing the area of the river-basins within which the gravel-covered tablelands are situated.

Fig. 12. Section of the gravel and brick-earth deposits exhibited in the cliff atForeland in the Isle of Wight.

Fig. 13. Comparative sections of the Brading and Freshwater valleys where they traverse the chalk.

Fig. 14. Contorted gravel and brick-earth in a pit near the railway at Anglesea, about 17 feet above the mean sea-level.

Fig. 15. Gravel in a pit near the "Tower of the Winds," Chilworth, 300 feet above the mean sea-level, where disturbance of the gravel appears to have arisen from the wasting of the beds beneath. The occurrence of white gravel, separated from the red by a black carbonaceous band, is also here seen.

 

Discussion.

The President referred to the raised beach at Brighton, which he had traced thence as far as Chichester. He inquired what evidence there was of the marine origin and contemporaneity of the beds identified with this beach by Mr. Codrington.

Mr. Whitaker noticed the occurrence of gravels similar to those

Quart. Journ. Geol. Soc. Vol. XXVI. Pl. XXXVI.

Quart. Journ. Geol. Soc. Vol. XXVI. Pl. XXXVII.

F. Dangerfield lith 22 Bedford S^t Covent Garden

described by Mr. Codrington on the slope between Canterbury and Herne Bay as indicative of the presence of a large river. He agreed with the author in considering that the white gravel was produced by the decolorization of the red; and remarked that it was unusual to find angular gravels of thoroughly marine type.

Mr. C. Moore remarked that the gravels and brick-earths from Salisbury westward are all of freshwater origin, and contain the remains of frogs in great abundance, together with freshwater shells, bones of Arvicolæ, &c.

Sir Charles Lyell was inclined to ascribe the formation of the gravels described to the sudden melting of snow in great quantities. He referred to the presence of sarsen-stones as indicating that there was force enough to carry large masses.

Prof. Ramsay referred to the great denudation of Eocene strata which must have taken place before the present form of the land was produced, as implying an immense amount of river-action, the immediate results of which are now masked by the modifications produced by subsequent subaerial changes of more limited extent. He maintained that the finding of flint implements at various elevationsonly rarely furnished direct evidence of change in the relative level of sea and land.

Mr. Codrington, in reply, stated that the gravels were not valley-gravels such as those mentioned by Mr. Moore. He did not see how glacial action could have spread the gravels over flat tablelands.

 

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1. Trans. Geol. Soc. vol. ii. 2nd series, p. 279.
2. Quart. Journ. Geol. Soc. vol. xiii. p. 45.
3. Gentleman's Mag. 1757, p. 64.
4. Warner's 'Collections for a History of Hants,' vol. i. p. 256.
5. Trans. Geol. Soc. vol. i. 2nd series, p. 90.
6. Quart. Journ. Geol. Soc. vol. xx. p. 188.
7. Quart. Journ. Geol. Soc. vol. xv. p. 215.
8. Ibid.
9. Vide Mr. Godwin-Austen, Quart. Journ. Geol. Soc. vol. xiii. p. 50, and Sir C. Lyell's 'Antiquity of Man,' p. 281.
10. The Rev. O. Fisher believes (Geological Mag. vol. i. p. 140) that the remains of E. meridionalis are also found in this deposit.
11. Quart. Journ. Geol. Soc. vol. xiii. p. 45.
12. Chemical and Physical Geology, vol. i. p. 166.
13. Quart. Journ. Geol. Soc. vol. xii. p. 136.
14. Ibid, vol. xiii. p. 48.
15. Quart. Journ. Geol. Soc. vol. vii. p. 25.
16. The New Forest, &c. By J. R. Wise.
17. Forbes's Memoir on the Fluviomarine Tertiaries of the Isle of Wight.
18. Flint Chips, p. 20.
19. Geology &c. of the Isle of Wight, p. 7.
20. Vide Webster in Sir H. Englefield's 'Isle of Wight;' Geological Survey Map and Memoir; Mr. Bristow in Forbes's Memoir on the Fluviomarine Tertiaries of the Isle of Wight; Mr. Godwin-Austen, Quart. Journ. Geol. Soc. vol. xi. p. 116.
21. Quart. Journ. Geol. Soc. vol. xiii. p. 66.
22. Forbes's Memoir, p. 6; Memoir of the Geological Survey of the Isle of Wight, p. 103; Godwin-Austen, Quart. Journ. Geol. Soc. vol. xi. p. 116; Prestwich, Quart. Journ. Geol. Soc. vol. xv. p. 215.
23. Forbes's Memoir on the Fluviomarine Tertiaries of the Isle of Wight, p. 7.
24. Memoirs of the Geological Survey of the Isle of Wight, p. 102.
25. Quart. Journ. Geol. Soc. vol. xi. p. 116.
26. Quart. Journ. Geol. Soc. vol. xv. p. 315.
27. There seems to be some reason to believe that a raised beach may exist at Bonchurch. Mr. Wilkins mentions the fact that the jaw-bone of a young whale and part of the skull of an elephant were found in drift at Horseshoe Bay.
28. Dixon's Geology, &c, of Sussex.
29. Quart. Journ. Geol. Soc. vol. xiii. p. 50.
30. Quart. Journ. Geol. Soc. vol. xv. p. 215.
31. Quart. Journ. Geol. Soc. vol. xiii. p. 65.
32. Phil. Trans. 1864.
33. Phil. Trans. 1860.
34. Reduced from the Map to accompany the Report on Salmon-Fisheries, 1861.

35. 		⁠
    Fall of the	Rhine.	Source to Dissentis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	60	feet per mile.
    „		Dissentis to Constance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	16	„
    „	Rhone.	Source to Brieg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	52	„
    „		Brieg to Lake of Geneva . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	10	„
    „	Clyde.	Source to Lanark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	20	„

36. Principles of Geology, vol. ii. p. 530.
37. Quart. Journ. Geol. Soc. vol. iii. p. 249.
38. Quart. Journ. Geol. Soc. vol. vii. p. 118.