The New Forest: its history and its scenery/Chapter 20

by John Richard de Capel Wise

 

CHAPTER XX.

THE GEOLOGY.

I have endeavoured, whenever there was an opportunity, to point out the natural history of the Forest, feeling sure that, from a lack of this knowledge, so many miss the real charms of the country. "One green field is like another green field," cried Johnson. Nothing can be so untrue. No two fields are ever the same. A brook flowing through the one, a narrow strip of chalk intersecting the other, will make them as different as Perthshire from Essex. Even Socrates could say in the Phædrus, τὰ μὲν οὖν χωρἰα καὶ τὰ δένδρα οὐδέν μ᾽ ἐθέλει διδάσκειν· and this arose from the state, or rather absence, of all Natural Science at Athens. Had that been different he would have spoken otherwise.

The world is another place to the man who knows, and to the man who is ignorant of Natural History. To the one the earth is full of a thousand significations, to the other meaningless.

First of all, then, for a few words on the geology of the Forest; for upon this everything depends—not only the scenery, but its Flora and Fauna, the growth of its trees and the course of its streams. Throughout it is composed of the Middle-Eocene, the Osborne and Headon Beds capping the central portion, with their fluvio-marine formation. The Upper Bagshot develops itself below them, and is succeeded by the Barton Clays, so well exposed on the coast, and finally by the Bracklesham Beds, which crop out in the valley of Canterton, trending in a south-easterly direction to Dibden.

Here, then, where the New Forest stands, in the Eocene period, rolled an inland sea, whose waves lashed the Wiltshire chalk hills on the north, moulding, with every stroke of their breakers, its chalk flints into pebbles, dashing them against its cliffs, as the waves do at this very hour those very same pebbles along the Hurst beach. Its south-western boundary-line between Ballard Head and the Needles was rent asunder by volcanic action, and the chalk-flints flung up vertically mark to this day the violence of the disruption.

Long after this the Isle of Wight was altogether separated by the Solent from the mainland, but still ages before the historic period. The various traditions, as to the former depth of the channel, how Sir Bevis, of Southampton, waded across it, how, too, the carts brought the Binstead stone for building Beaulieu Abbey over the dry bed at low water, have been previously given. The passage, too, in Diodorus Siculus has been already examined,^[1] and there can be no doubt, notwithstanding his also making it, like the traditions, a peninsula at low water, that his Ictis is the Isle of Wight and not St. Michael's Mount. The mere local evidence of the mass of tin, the British road—more like a deep trench than a road—still plainly traceable across the Forest, the names along it corresponding with that of its continuation in the Island, would alone, most assuredly, show that this was the place whence the first traders, and, in after-times, the Romans, exported their tin. We must, however, remember that the channel of the Solent was caused by depression rather than by excavation; and that at this moment an alteration in the levels, as noticed by Mr. Austen,^[2] is going on eastward of Hurst Castle.

The drift, which spreads over the whole of the New Forest, is not very interesting. No elephants' tusks, or elks' horns, so far as I know, have ever been discovered. A few species of Terebratula and Pecten, some flint knives, and the os inominatum, of probably Bos longifrons, mentioned farther on, are the only things at present found. Still, in one way, it is most interesting, as completely disproving the Chroniclers' accounts that, before its afforestation by the Conqueror, the district of the Forest was so fertile. The fact is a sheer impossibility. No wheat could ever be grown on this great bed of chalk-gravel, which is varied only by patches of sand.

But nowhere, perhaps, in the world can we see the stratification of the upper portion of the Middle-Eocene better than at Hordle and Barton, as the sea serves to keep the different strata exposed. The beds dip easterly with a fall of about one in a hundred, though, at the extreme west, at High Cliff, it is much less, and here and there in some few places they lie almost horizontally.^[3] At Hordle they seem to have been deposited in a river of a very uniform depth. There is but one single fault in the whole series, just under Mead End, where all the beds have alike suffered. Here and there, however, they are deposited with an undulating line; and here and there, too, a rippled surface occurs, caused by the action of small waves. The river appears to have varied very much in the amount and force of its stream, as some of the beds, where the shells are less frequent, have been deposited very rapidly, whilst others, where the organic remains are more abundant, have been laid on very slowly and in very still water.^[4]

It will be impossible to examine all the beds. One or two, however, may be mentioned. And since the beds rise at the east we will begin from Milford. First of all, at Mineway, there runs a remarkable band of fine sand, the "Middle Marine Bed," discovered some twenty-five years ago, by Mr. Edwards, and subsequently successfully worked by Mr. Higgins. It is seldom, however, exposed for more than a few yards; but that is sufficient to show, that after the elevation of the beds beneath they once more subsided, and the sea came over them again, and after that they were once again elevated.

Just below Hordle House rises the "Crocodile Bed," running out of the cliff about three hundred yards from Beckton Bunny. The lowest part of it teems with fish-scales, teeth, crocodile plates, ophidian vertebrae, seed vessels, and other vegetable matter, very often mixed in a coprolitic bed, just beneath a band of tough clay, the specimens being more frequent to the east than the west. The accompanying section (I.) will, perhaps, not only serve to show the situation of the bed, but also those above and below. My measurements will be found to differ slightly from Sir Charles Lyell's^[5] and Dr. Wright's;^[6] but this is owing to their having been taken in different places.

Immediately under the "Leaf Bed," which, as seen in the opposite section, rises from the shore to the west of Hordle House, comes the lowest bed of the Lower Freshwater Series, formed of blue sandy clay sixteen feet in thickness, from whence Mr. Falconer obtained so many of his mammalian remains.^[7]

It is a bed, however, which is seldom open, and can be worked only at particular tides. It may easily be recognized as lying between the Leaf Bed and the well-marked Lignite Bed, which shows the first traces of salt-water, and where, in the lower portion, Neritina concava may be abundantly found. This last bed may be well seen at Beckton Bunny (section II.). The lignite, however, though it will give a good deal of heat, will not blaze. Locally it is sometimes used for making black paint.

Passing on to Beckton Bunny we reach the first true bed of the Lower Marine Formation, which rises a little eastward of that ravine. I have distinguished it as the Olive Bed, from the abundance of specimens of Oliva Branderi, forming the equivalent to number eighteen in Dr. Wright's arrangement, and which, when worked, emits a strong smell of sulphur.

Immediately under the Olive Bed, as seen in the opposite section (II.), taken immediately on the west side of the Bunny, rises grey sand, seventeen feet and half in thickness, possessing only a few casts of shells. The next bed, however, composed also of grey sand, rising about three hundred yards farther on, is, perhaps, the richest in the whole of this Marine series, and its shells the best preserved. It may at once be recognised by the profusion of Chama squamosa, from which it has been called the Chama Bed. Specimens of Arca Branderi and Solen gracilis may be found here as perfect as on the day they were deposited.

A little farther on, nearly under the Gangway, rises the Barton clay, encrusted with Crassatella sulcata.^[8] And here, on looking at the cliff, we may notice how all the beds, as they rise westward, gradually lose their clayey character, and run into sand, which will account for this part of the cliff foundering so fast. The water percolates through the sand down to the Barton Beds, and the loose mass above is thus launched into the sea.

Below the Barton Coastguard Station rises another bed of green clay, containing sharks' teeth and the bones of fish. About a mile farther on, the High Cliff Beds emerge rich with Cassis ambigua and Cassidaria nodosa. And below them, seen in the channel of the stream flowing through Chewton Bunny, rises a bed of bright metallic-looking, green clay, the Nummulina Prestwichiana Bed of Mr. Fisher, containing sharks' teeth and some few shells. Beyond, a little to the west of High Cliff Castle, occurs the well-marked Pebble Bed, the commencement of the Bracklesham Series, containing rolled chalk flints, and casts of shells. Next follow grey sands full of fossil wood and vegetable matter, marked by' a course of oxydized ironstone-septaria. Then succeeds another Pebble Bed, and lastly appear the grey Bracklesham Sands.^[9]

We have thus gone through the principal beds, both of the Freshwater and Marine Series, as far as they are exposed in this section along the sea-coast. The fluvio-marine beds stretch away eastward as far as Beaulieu and Hythe, but their clays here contain very few shells. On the other hand, the Bracklesham Beds, trend away northward towards Stony-Cross, appearing in the valley, and cropping out again on the other side of the Southampton Water.

Some few words must be said about them. The highest beds, known as the Hunting Bridge Beds, occur in Copse St. Leonards, not far from the Fritham Road.^[10] In a descending order, separated by thirty or forty feet of unfossiliferous clays, come the Shepherd's Gutter Beds, to be found about half-a-mile lower down the King's Gairn Brook; and below them, again, separated by forty or fifty feet of unfossiliferous clays, and situated somewhat more than a mile lower down the same stream, rise the Brook Beds. Still farther down, too, from some shells very lately discovered at Cadenham, it is supposed that the Cerithium Bed of Stubbington and Bracklesham Bay will be found, but this is not yet ascertained.

The Hunting Bridge Beds I have never examined, but subjoin their measurements, as also their most typical shells,^[11] and must here content myself to give a general description of the Shepherd's Gutter and Brook Beds. The former, the equivalent to the Nummulina Bed at Stubbington, Bracklesham,

and White-Cliff Bay, is so called from a small stream at the foot of Bramble Hill Wood, about a mile due north of the King's Gairn Brook. The measurements are as follow :— (1) Gravel from one to five feet; (2) light-coloured clay, with a few fossils sparingly distributed, five to six feet; (3) Turritella carinifera bed, one foot and a half; (4) fossil bed, characterized by Conus deperditus, and the abundance of Pecten corneus within a few inches of the bottom, one foot and a half.

It is worth noticing that these, like all the Bracklesham beds, roll. In a pit which Mr. Keeping and myself dug we found there had been a regular displacement of the gravel, and that the beds rose at an angle of thirty degrees, whilst the fossil bed was three feet lower on one side than the other of the pit. In another, after cutting through a foot of gravel, in which we found the os inominatum, of probably Bos longifrons,^[12] and a bed of sandy clay about two feet in thickness, we came upon a deposit of gravel about four inches thick, lying in the depressions of the stiff brown clay which succeeded, and in which still remained roots and vegetable matter. Thus we can plainly see that, after the clay had been deposited, vegetable, and perhaps animal, life flourished. Then came the gravel, carrying all before it, and in its turn, too, was nearly swept away, and only left here and there in a few scattered patches.

Perhaps, nothing is so startling as this insecurity of life. As was the Past so will be the Future, guided, though, always by that Law, which at every step still rises, moving in no circle, but out of ruin bringing order, and from Death, Life.

The Brook Beds I can best describe for the general reader by an account of a pit which Mr. Keeping and myself made. It was sunk about 20 feet from the King's Gairn Brook, and measured about 6 yards long by 4 broad. We first cut through a loamy sand, measuring 8 feet, and then came upon 19 inches of gravel, where at the base stretched the half fossilized trunk of an oak, and a thick drift of leaves mixed with black peaty matter, the remains of some primæval forest. Three feet of light-coloured clay, unfossiliferous, succeeded; and then came the Corbula Bed, with its myriads of Corbula pisum, massed together, nearly all pierced by their enemies, the Murices. Stiff light-coloured clay, measuring 18 inches, followed, revealing some of the shells, which were to be found so plentiful in the next stratum. Here, at the Pleurotoma attenuata Bed, our harvest commenced, and since Mr. Keeping has worked these beds, no spot has ever yielded such rich results. Every stroke of the pick showed the pearl and opal-shaded colours of the nautilus, and the rich chestnut glaze of the Pecten corneus, whilst at the bottom lay the great thick-shelled Carditæ planicostæ. Inside one of these were enclosed two most lovely specimens of Calyptræa trochiformis. Mr. Keeping here, too, found a young specimen of Natica cepacea (?), and I had the good fortune to turn up the largest Pleurotoma attenuata ever yet discovered, measuring 4½ inches in length, and 3¼ inches in circumference round the thickest whorl.

We were now down no less than 8 feet. And at this stage the water from the brook, which had been threatening, began to burst in upon us from the north side. We, however, with intervals of bailing, still pushed on till we reached the next bed of pale clay, measuring from 7 to 8 inches, containing Cassidariæ highly pyritised, and sharks' teeth, amongst which Mr. Keeping discovered an enormous spine, measuring at least 10 inches in length, but we were unable to take it out perfect. The water had all this time been gaining upon us, in spite of our continuous efforts to bail it with buckets. We, however, succeeded in making the Voluta horrida bed, which seemed, at this spot, literally teeming with shells. Each spitful, too, showed specimens of fruit, earbones, fish-palates, drift-wood, and those nodular concretions which had gathered round some berry or coral.^[13]

At this point, the water, which was now pouring through the side in a complete stream, and a rumbling noise, showed danger was imminent. Hastily picking up our tools and fossils we retreated. In a moment a mass of clay began to move, and two or three tons, completely burying our bed, fell where we had stood. Founder after founder kept succeeding, driving the water up to higher levels. We procured assistance, but precious time was lost. Night began to fall, and we were obliged to leave unworked one of the richest spots which, in these beds, may, perhaps, ever be met.

As it was, we found no less than sixty-one species, including in all 230 good cabinet specimens, which, considering the small size of the pit, and our limited time, and the great disadvantages under which we worked, well showed the richness of these beds.

Merely, however, collecting fossils for collecting's sake is useless. The aim of geology is to enable us to understand how this world was made—how form followed form, how type after type took life and then passed away, and the higher organization ever succeeded the lower. The Middle-Eocene ought to be to us particularly interesting, separating us, on the one hand, from those monsters which had filled the previous Age, and, on the other, presenting the first appearances of those higher mammals which should serve the future wants of man. The pterodactyle no longer darkened the air. The iguanodon now slept in its grave of chalk. A new earth, covered with new types and new forms, had appeared. It is a strange sight which the Hordle Cliffs unveil. Here, beneath a sun fiercer than in our tropics, the crocodile basked in its reed beds. Here the alligator crimsoned the stream, as he struck his jaws into his victim; whilst the slow tryonyx paddled through the waves, and laid its eggs on the sand, where its plates are now bedded.

The very rushes, which grew on the river banks, lie caked together, with the teeth of the rats which harboured in them. The pine-cones still, too, lie there, their surfaces scarcely more abraded than when they dropped from the tree into the tepid waters. Along the muddy river shore browsed the paloplothere, whilst his mate crushed through the jungle of club-mosses. Groves of palms stood inland, or fringed the banks, swarming with land-snakes. Birds waded in the shallows. But no human voice sounded: nothing was to be heard but the screaming of the river-fowl, and the deep bellow of the tapir-shaped palæothere, and the wolf-like bark of the hyænodon.

This description is no mere fancy, but taken from the remains actually discovered in the Hordle Cliffs. I have had no need to borrow from the fossils of the Headon and Binstead Beds, or the caves of Montmartre. On these cliffs, too, is scored the history of the past. Here lie the little Nuculæ, still crimson and pink as when they first settled down through the water into their bed of sand; and teeth of dichodons still bright with enamel. The struggle of life raged as fiercely then as now. And the pierced skull of the palæothere still tells where it received its death-wound from its foe the crocodile.

But other things do they reveal. They plainly show, as was, I believe, first suggested by Mr. Searles Wood, that in the Middle-Eocene period Europe and America were connected. The pachyderms of Hordle are allied to the tapirs of the New World. The same alligators still swim in the warm rivers of Florida: and the same type of sauroid fish, whose scales spangle the Freshwater Beds, is now only found in the West.

Footnotes

1. See chap, v., pp. 57, 58. It is just possible that by his "τὰς πλησίον νήσους," Diodorus may mean the Shingle Islands, which we have described in chapter xiv. p. 151, and whose sudden appearance and disappearance would lead to the most extravagant reports.
2. "On the Newer Deposits of the Sussex Coast:" Geological Journal, vol. xiii. pp. 64, 65.
3. In the coast-map at p. 148, the principal beds are marked, so that, I trust, there will be no difficulty in finding them.
4. For the direction of the river from east to west, see a paper "On the Discovery of an Alligator and several New Mammalia in Hordwell Cliff," by Searles Wood, F.G.S.: London Geological Journal, No. 1., pp. 6, 7.
5. "The Freshwater Strata of Hordwell Cliff, Beacon Cliff, and Barton Cliff:" Transactions of the Geological Society, second series, vol. ii., p. 287.
6. "Stratigraphical Account of the Section of Hordwell, Beckton, and Barton Cliffs:" The Annals and Magazine of Natural History, June, 1851. In making these measurements I was very greatly assisted by the Rev. W. Fox, who was most untiring to ensure accuracy.
7. See the Geological Journal, vol. iv., p. 17; as also, Professor Owen's Monograph on "The Fossil Reptilia of the London Clay," published by the Palæontographical Society, 1850, p. 48.
8. Some of the most characteristic shells in this bed may perhaps be mentioned:—

   Pleurotoma exorta. Sol.	Scalaria reticulata. Sow.
   Terebellum fusiforme. Lam.	Scalaria semicostata. Sow.
   Murex minax. Sol.	Littorina sulcata. Pilk.
   Murex asper. Sol.	Solarium plicatum. Lam.
   Murex bispinosus. Sow.	Hipponyx squamiformis. Lam.
   Typhis pungeus. Sol.	Fusus porrectus. Sol.
   Voluta ambigua. Sol.	Fusus errans. Sol.
   Voluta costata. Sol.	Fusus longævus. Sol.
   Voluta luctatrix. Sol.	Bulla constricta. Sow.
   Dentalium striatum Sow.	Bulla elliptica. Desh.

   I scarcely need, I hope, refer the reader either to Mr. Edwards' Monograph on the Eocene Mollusca, 1849, 1852, 1854, 1856, or to Mr. Searles Wood's Monograph on the same subject, both in course of publication by the Palæontographical Society. There is an excellent table of the Barton shells, by Mr. Prestwich, in the Geological Journal, vol. xiii. pp. 118-126.

9. For the High Cliff Beds, see Mr. Fisher's paper on the Bracklesham Sands of the Isle of Wight Basin, in the Proceedings of the Geological Society, May, 1862, pp. 86-91, whose divisions are here followed.
10. All these beds are shown in the large map by the word "Fossils," there not being space enough to particularize each bed.
11. These beds were discovered by Mr. Fisher in 1861, and for the following measurements I am indebted to Mr. Keeping. We find, about one hundred yards in a south-eastward direction from the point where the footpath from Brook to Fritham crosses the stream, (1) the Coral Bed, the equivalent of that at Stubbington, full of crushed Dentalia and Serpulæ, six inches. (2) Sandy light blue clay, with very few fossils, seven feet. (3) Verdigris-green and slate-coloured clay, characterized near the top by a new species of Dentalium, Serpulorbis Morchii (?), and Spondylus rarispina. The other typical shells are Voluta Maga, several species of Arca and Corbula gallica, five feet. It is in this bed that large roots of trees and ferns are found.
    No persons, however, I should suppose, would think of examining any of these beds without first consulting Mr. Fisher's most valuable paper on the Bracklesham Beds in the Proceedings of the Geological Society, May, 1862. And I should further most strongly advise them, if they wish to become practically acquainted with the beds, to procure the assistance of Mr. Keeping, of Freshwater, in the Isle of Wight.
    I may here further mention that a well is at the present moment being sunk at Emery Down, and which, as I learn from Mr. Keeping, gives the following interesting measurements:—(1) Beds of marl, containing Voluta geminata, discovered forty years ago, at Cutwalk Hill, by Sir Charles Lyell, and now re-discovered, and a small Marginella, seven feet. (2) Bed of bluish sandy clay, which becomes, when weathered, excessively brown. This bed, very rich in fossils, which are in a good state of preservation, is equivalent to what is now called the Middle Marine Bed, at Hordle and Brockenhurst, sixteen to nineteen feet. (3) Hordle Freshwater Beds, containing two species of Potanomya, and comminuted shells, fifteen feet. (4) Upper Bagshot Sands, measuring, as far as the workmen have gone, twenty feet, and below which lies the water at the top of the clay. The important point to be noticed is the extreme thinning out of the Hordle Freshwater Beds, which, from the depth of two hundred and fifty feet at Barton have here shrunk to fifteen. Mr. Prestwich has suggested that these beds, as they advance in a north-easterly direction, become more marine, which seems here to be confirmed.
12. I say probably, for Professor Owen, who examined the specimen, states that it is of a bovine animal of the size of Bos longifrons, but does not yield characters for an exact specific identification. I may here add that the celt mentioned at p. 207, foot-note, is hardly satisfactory.
13. I had intended to have accompanied this description with a group of some of the best fossils from this pit, including the fruit, fish-spines, and palates, and the large Pleurotoma attenuata. It was, in fact, commenced by the artist. But the specimens were obliged to be so greatly reduced, that the drawing gave no complete idea of their form and beauty, and would only have confused the reader. I have, therefore, contented myself with figuring at p. 249, in its matrix of clay, the rare Natica cepacea (?), which has passed into Mr. Edwards' fine collection, and who has kindly allowed me the use of it, with the characteristic Cassidaria nodosa, and a lovely Calyptrcea trochiformis, found, as mentioned, inside a Cardita. At p. 244, the specimens given from the Shepherd's Gutter Beds are Cerithium triliuum (Edw. MS.), Voluta uniplicata, and, in the centre, a shell, showing oblique folds on the columella, which Mr. Edwards thinks may be identical with Fusus incertus of Deshayes.