If the reader will refer to the section of the Pleistocene sands and gravels of Menchecourt, near Abbeville, given at page 96, he will perfectly understand the relations of the ancient Thames alluvium to the modern channel and plain of the river, and their relation, on the other hand, to the boundary formations of older date, whether Tertiary or Cretaceous.

So far as they are known, the fossil mollusca and mammalia of the two districts also agree very closely, the Cyrena fluminalis being common to both, and being the only extra-European sh.e.l.l, this and all the species of testacea being Recent. Of this agreement with the living fauna there is a fine ill.u.s.tration in Ess.e.x; for the determination of which we are indebted to the late Mr. John Brown, F.G.S., who collected at Copford, in Ess.e.x, from a deposit containing bones of the mammoth, a large bear (probably Ursus spelaeus), a beaver, stag, and aurochs, no less than sixty-nine species of land and freshwater sh.e.l.ls. Forty-eight of these were terrestrial, and two of them, Helix incarnata and H. ruderata, no longer inhabit the British Isles, but are still living on the continent, ruderata in high northern lat.i.tudes.*

(* "Quarterly Journal of the Geological Society" volume 8 1852 page 190. Mr. Brown calls them extinct species, which may mislead some readers, but he merely meant extinct in England. See also Jeffreys, "Brit. Conch." page 174.)

The Cyrena fluminalis and the Unio littoralis, to which last I shall presently allude, were not among the number.

I long ago suggested the hypothesis, that in the basin of the Thames there are indications of a meeting in the Pleistocene period of a northern and southern fauna. To the northern group may have belonged the mammoth (Elephas primigenius) and the Rhinoceros tichorhinus, both of which Pallas found in Siberia, preserved with their flesh in the ice.

With these are occasionally a.s.sociated the reindeer. In 1855 the skull of the musk ox (Bubalus moschatus) was also found in the ochreous gravel of Maidenhead, by the Reverend C. Kingsley and Mr. Lubbock; the identification of this fossil with the living species being made by Professor Owen. A second fossil skull of the same arctic animal was afterwards found by Mr. Lubbock near Bromley, in the valley of a small tributary of the Thames; and two other skulls, those of a bull and a cow were dug up near Bath Easton from the gravel of the valley of the Avon by Mr. Charles Moore. Professor Owen has truly said, that "as this quadruped has a const.i.tution fitting it at present to inhabit the high northern regions of America, we can hardly doubt that its former companions, the warmly-clad mammoth and the two-horned woolly rhinoceros (R. tichorhinus), were in like manner capable of supporting life in a cold climate."*

(* "Quarterly Journal of the Geological Society" volume 12 1856 page 124.)

I have already alluded to the recent discovery of this same ox near Chauny, in the valley of the Oise, in France; and in 1856 I found a skull of it preserved in the museum at Berlin, which Professor Quenstedt, the curator, had correctly named so long ago as 1836, when the fossil was dug out of drift, in the hill called the Kreuzberg, in the southern suburbs of that city. By an account published at the time, we find that the mammalia which accompanied the musk ox were the mammoth and tichorhine rhinoceros, with the horse and ox;* but I can find no record of the occurrence of a hippopotamus, nor of Elephas antiquus or Rhinoceros leptorhinus, in the drift of the north of Germany, bordering the Baltic.

(* "Leonhard and Bronn's Jahrbuch" 1836 page 215.)

On the other hand, in another locality in the same drift of North Germany, Dr. Hensel, of Berlin, detected, near Quedlinburg, the Norwegian Lemming (Myodes lemmus), and another species of the same family called by Pallas Myodes torquatus (by Hensel, Misothermus torquatus)--a still more arctic quadruped, found by Parry in lat.i.tude 82 degrees, and which never strays farther south than the northern borders of the woody region. Professor Beyrich also informs me that the remains of the Rhinoceros tichorhinus were obtained at the same place.*

(* "Zeitschrift der Deutschen Geologischen Gesellschaft"

volume 7 1855 page 497 etc.)

As an example of what may possibly have const.i.tuted a more southern fauna in the valley of the Thames, I may allude to the fossil remains found in the fluviatile alluvium of Gray's Thurrock, in Ess.e.x, situated on the left bank of the river, 21 miles below London. The strata of brick-earth, loam, and gravel exposed to view in artificial excavations in that spot, are precisely such as would be formed by the silting up of an old river channel. Among the mammalia are Elephas antiquus, Rhinoceros leptorhinus (R. megarhinus, Christol), Hippopotamus major, species of horse, bear, ox, stag, etc., and, among the accompanying sh.e.l.ls, Cyrena fluminalis, which is extremely abundant, instead of being scarce, as at Abbeville. It is a.s.sociated with Unio littoralis also in great numbers and with both valves united. This conspicuous freshwater mussel is no longer an inhabitant of the British Isles, but still lives in the Seine, and is still more abundant in the Loire. Another freshwater univalve (Paludina marginata, Michaud), not British, but common in the south of France, likewise occurs, and a peculiar variety of Cyclas amnica, which by some naturalists has been regarded as a distinct species. With these, moreover, is found a peculiar variety of Valvata piscinalis.

If we consult Dr. Von Schrenck's account of the living mammalia of Mongolia, lying between lat.i.tude 45 and 55 degrees north, we learn that, in that part of North-Eastern Asia recently annexed to the Russian empire, no less than thirty-four out of fifty-eight living quadrupeds are identical with European species, while some of those which do not extend their range to Europe are arctic, others tropical forms. The Bengal tiger ranges northwards occasionally to lat.i.tude 52 degrees north, where he chiefly subsists on the flesh of the reindeer, and the same tiger abounds in lat.i.tude 48 degrees, to which the small tailless hare or pika, a polar resident, sometimes wanders southwards.*

(* Mammalia of Amoorland, "Natural History Review" volume 1 1861 page 12.)

We may readily conceive that the countries now drained by the Thames, the Somme, and the Seine, were, in the Pleistocene period, on the borders of two distinct zoological provinces, one lying to the north, the other to the south, in which case many species belonging to each fauna endowed with migratory habits, like the living musk-ox or the Bengal tiger, may have been ready to take advantage of any, even the slightest, change in their favour to invade the neighbouring province, whether in the summer or winter months, or permanently for a series of years, or centuries. The Elephas antiquus and its a.s.sociated Rhinoceros leptorhinus may have preceded the mammoth and tichorhine rhinoceros in the valley of the Thames, or both may have alternately prevailed in the same area in the Pleistocene period.

In attempting to settle the chronology of fluviatile deposits, it is almost equally difficult to avail ourselves of the evidence of organic remains and of the superposition of the strata, for we may find two old river-beds on the same level in juxtaposition, one of them perhaps many thousands of years posterior in date to the other. I have seen an example of this at Ilford, where the Thames, or a tributary stream, has at some former period cut through sands containing Cyrena fluminalis, and again filled up the channel with argillaceous matter, evidently derived from the waste of the Tertiary London Clay. Such shiftings of the site of the main channel of the river, the frequent removal of gravel and sand previously deposited, and the throwing down of new alluvium, the flooding of tributaries, the rising and sinking of the land, fluctuations in the cold and heat of the climate--all these changes seem to have given rise to that complexity in the fluviatile deposits of the Thames, which accounts for the small progress we have hitherto made in determining their order of succession, and that of the imbedded groups of quadrupeds. It may happen, as at Brentford and Ilford, that sand-pits in two adjoining fields may each contain distinct species of elephant and rhinoceros; and the fossil remains in both cases may occur at the same depth from the surface, yet may be severally referable to different parts of the Pleistocene epoch, separated by thousands of years.

The relation of the glacial period to alluvial deposits, such as that of Gray's Thurrock, where the Cyrena fluminalis, Unio littoralis, and the hippopotamus seem rather to imply a warmer climate, has been a matter of long and animated discussion. Patches of the northern drift, at elevations of about 200 feet above the Thames, occur in the neighbourhood of London, as at Muswell Hill, near Highgate. In this drift, blocks of granite, syenite, greenstone, Coal-measure sandstone with its fossils, and other Palaeozoic rocks, and the wreck of Chalk and Oolite, occur confusedly mixed together. The same glacial formation is also found capping some of the Ess.e.x hills farther to the east, and extending some way down their southern slopes towards the valley of the Thames. Although no fragments washed out of these older and upland drifts have been found in the gravel of the Thames containing elephants'

bones, it is fair to presume, as Mr. Prestwich has contended,* that the glacial formation is the older of the two.

(* Prestwich, "Quarterly Journal of the Geological Society"

volume 11 1855 page 110; ibid. volume 12 1856 page 133; ibid. volume 17 1861 page 446.)

In short, we must suppose that the basin of the Thames and all its fluviatile deposits are post-glacial, in the modified sense of that term; i.e. that they were subsequent to the drift of the central and northern counties.

Having offered these general remarks on the alluvium of the Thames, I may now say something of the implements. .h.i.therto discovered in it. In the British Museum there is a flint weapon of the spear-headed form, such as is represented in Figure 8, which we are told was found with an elephant's tooth at Black Mary's, near Gray's Inn Lane, London. In a letter dated 1715, printed in Herne's edition of "Leland's Collectanea,"

volume 1 page 73, it is stated to have been found in the presence of Mr.

Conyers, with the skeleton of an elephant.*

(* Evans, "Archaeologia" 1860.)

So many bones of the elephant, rhinoceros, and hippopotamus have been found in the gravel on which London stands, that there is no reason to doubt the statement as handed down to us. Fossil remains of all these three genera have been dug up on the site of Waterloo Place, St. James's Square, Charing Cross, the London Docks, Limehouse, Bethnal Green, and other places within the memory of persons now living. In the gravel and sand of Shacklewell, in the north-east district of London, I have myself collected specimens of the Cyrena fluminalis in great numbers (see Figure 17 c), with the bones of deer and other mammalia.

In the alluvium also of the Wey, near Guildford, in a place called Pease Marsh, a wedge-shaped flint implement, resembling one brought from St. Acheul by Mr. Prestwich, and compared by some antiquaries to a sling-stone, was obtained in 1836 by Mr. Whitburn, 4 feet deep in sand and gravel, in which the teeth and tusks of elephants had been found.

The Wey flows through the gorge of the North Downs at Guildford to join the Thames. Mr. Austen has shown that this drift is so ancient that one part of it had been disturbed and tilted before another part was thrown down.*

(* "Quarterly Journal of the Geological Society" volume 7 1851 page 278.)

Among other places where flint tools of the antique type have been met with in the course of the last three years, I may mention one of an oval form found by Mr. Whitaker in the valley of the Darent, in Kent, and another which Mr. Evans found lying on the sh.o.r.e at Swalecliff, near Whitstable, in the same county, where Mr. Prestwich had previously described a freshwater deposit, resting on the London Clay, and consisting chiefly of gravel, in which an elephant's tooth and the bones of a bear were embedded. The flint implement was deeply discoloured and of a peculiar bright light-brown colour, similar to that of the old fluviatile gravel in the cliff.

Another flint implement was found in 1860 by Mr. T. Leech, at the foot of the cliff between Herne Bay and the Reculvers, and on further search five other specimens of the spear-head pattern so common at Amiens.

Messrs. Prestwich and Evans have since found three other similar tools on the beach, at the base of the same wasting cliff, which consists of sandy Eocene strata, covered by a gravelly deposit of freshwater origin, about 50 feet above the sea-level, from which the flint weapons must have been derived. Such old alluvial deposits now capping the cliffs of Kent seem to have been the river-beds of tributaries of the Thames before the sea encroached to its present position and widened its estuary. On following up one of these freshwater deposits westward of the Reculvers, Mr. Prestwich found in it, at Chislet, near Grove Ferry, the Cyrena fluminalis among other sh.e.l.ls.

The changes which have taken place in the physical geography of this part of England during, or since, the Pleistocene period, have consisted partly of such encroachments of the sea on the coast as are now going on, and partly of a general subsidence of the land. Among the signs of the latter movement may be mentioned a freshwater formation at Faversham, below the level of the sea. The gravel there contains exclusively land and fluviatile sh.e.l.ls of the same species as those of other localities of the Pleistocene alluvium before mentioned, and must have been formed when the river was at a higher level and when it extended farther east. At that era it was probably a tributary of the Rhine, as represented by Mr. Trimmer in his ideal restoration of the geography of the olden time.*

(* "Quarterly Journal of the Geological Society" volume 9 1853 Plate 8 Number 4.)

For England was then united to the continent, and what is now the North Sea was land. It is well known that in many places, especially near the coast of Holland, elephants' tusks and other bones are often dredged up from the bed of that shallow sea, and the reader will see in the map given in Chapter 13 how vast would be the conversion of sea into land by an upheaval of 600 feet. Vertical movements of much less than half that amount would account for the annexation of England to the continent, and the extension of the Thames and its valley far to the north-east, and the flowing of rivers from the easternmost parts of Kent and Ess.e.x into the Thames, instead of emptying themselves into its estuary.

More than a dozen flint weapons of the Amiens type have already been found in the basin of the Thames; but the geological position of no one of them has as yet been ascertained with the same accuracy as that of many of the tools dug up in the valley of the Somme.

FLINT IMPLEMENTS OF THE VALLEY OF THE OUSE, NEAR BEDFORD.

The ancient fluviatile gravel of the valley of the Ouse, around Bedford, has been noted for the last thirty years for yielding to collectors a rich harvest of the bones of extinct mammalia. By observations made in 1854 and 1858, Mr. Prestwich had ascertained that the valley was bounded on both sides by Oolitic strata, capped by boulder clay, and that the gravel Number 3, Figure 23, contained bones of the elephant, rhinoceros, hippopotamus, ox, horse, and deer, which animals he therefore inferred must have been posterior in date to the boulder clay, through which, as well as the subjacent Oolite, the valley had been excavated. Mr. Evans had found in the same gravel many land and freshwater sh.e.l.ls, and these discoveries induced Mr. James Wyatt, of Bedford, to pay two visits to St. Acheul in order to compare the implement-bearing gravels of the Somme with the drift of the valley of the Ouse. After his return he resolved to watch carefully the excavation of the gravel-pits at Biddenham, 2 miles west-north-west of Bedford, in the hope of finding there similar works of art. With this view he paid almost daily visits for months in succession to those pits, and was at last rewarded by the discovery of two well-formed implements, one of the spear-head and the other of the oval shape, perfect counterparts of the two prevailing French types. Both specimens were thrown out by the workmen on the same day from the lowest bed of stratified gravel and sand, 13 feet thick, containing bones of the elephant, deer, and ox, and many freshwater sh.e.l.ls. The two implements occurred at the depth of 13 feet from the surface of the soil, and rested immediately on solid beds of Oolitic limestone, as represented in the accompanying section (Figure 23).

Having been invited by Mr. Wyatt to verify these facts, I went to Biddenham within a fortnight of the date of his discovery (April 1861), and, for the first time, saw evidence which satisfied me of the chronological relations of those three phenomena, the antique tools, the extinct mammalia, and the glacial formation. On that occasion I examined the pits in company with Messrs. Prestwich, Evans, and Wyatt, and we collected ten species of sh.e.l.ls from the stratified drift Number 3, or the beds overlying the lowest gravel from which the flint implements had been exhumed. They were all of common fluviatile and land species now living in the same part of England. Since our visit, Mr. Wyatt has added to them Paludina marginata, Michaud (Hydrobia of some authors), a species of the South of France no longer inhabiting the British Isles.

The same geologist has also found, since we were at Biddenham, several other flint tools of corresponding type, both there and at other localities in the valley of the Ouse, near Bedford.

[Figure 23. Valley of the Ouse]

(FIGURE 23. SECTION ACROSS THE VALLEY OF THE OUSE, TWO MILES WEST-NORTH-WEST OF BEDFORD.*

(* Prestwich, "Quarterly Journal of the Geological Society"

volume 17 1861 page 364; and Wyatt, "Geologist" 1861 page 242.)

1. Oolitic strata.

2. Boulder clay, or marine northern drift, rising to about ninety feet above the Ouse.

3. Ancient gravel, with elephant bones, freshwater sh.e.l.ls, and flint implements.

4. Modern alluvium of the Ouse.

a. Biddenham gravel pits, at the bottom of which flint tools were found.)

The boulder clay Number 2 extends for miles in all directions, and was evidently once continuous from b to c before the valley was scooped out. It is a portion of the great marine glacial drift of the midland counties of England, and contains blocks, some of large size, not only of the Oolite of the neighbourhood, but of Chalk and other rocks transported from still greater distances, such as syenite, basalt, quartz, and New Red Sandstone. These erratic blocks of foreign origin are often polished and striated, having undergone what is called glaciation, of which more will be said by and by. Blocks of the same mineral character, embedded at Biddenham in the gravel Number 3, have lost all signs of this striation by the friction to which they were subjected in the old river bed.

The great width of the valley of the Ouse, which is sometimes 2 miles, has not been expressed in the diagram. It may have been shaped out by the joint action of the river and the tides when this part of England was emerging from the waters of the glacial sea, the boulder clay being first cut through, and then an equal thickness of underlying Oolite.

After this denudation, which may have accompanied the emergence of the land, the country was inhabited by the primitive people who fashioned the flint tools. The old river, aided perhaps by the continued upheaval of the whole country, or by oscillations in its level, went on widening and deepening the valley, often shifting its channel, until at length a broad area was covered by a succession of the earliest and latest deposits, which may have corresponded in age to the higher and lower gravels of the valley of the Somme, already described.

At Biddenham, and elsewhere in the same gravel, remains of Elephas antiquus have been discovered, and Mr. Wyatt obtained, January 1863, a flint implement a.s.sociated with bones and teeth of hippopotamus from gravel at Summerhouse hill, which lies east of Bedford, lower down the valley of the Ouse, and 4 miles from Biddenham.

One step at least we gain by the Bedford sections, which those of Amiens and Abbeville had not enabled us to make. They teach us that the fabricators of the antique tools, and the extinct mammalia coeval with them, were all post-glacial.

FLINT IMPLEMENTS IN A FRESHWATER DEPOSIT AT HOXNE IN SUFFOLK [17].

So early as the first year of the nineteenth century, a remarkable paper was communicated to the Society of Antiquaries by Mr. John Frere, in which he gave a clear description of the discovery at Hoxne, near Diss, in Suffolk, of flint tools of the type since found at Amiens, adding at the same time good geological reasons for presuming that their antiquity was very great, or, as he expressed it, beyond that of the present world, meaning the actual state of the physical geography of that region. "The flints," he said, "were evidently weapons of war, fabricated and used by a people who had not the use of metals. They lay in great numbers at the depth of about 12 feet in a stratified soil which was dug into for the purpose of raising clay for bricks. Under a foot and a half of vegetable earth was clay 7 1/2 feet thick, and beneath this one foot of sand with sh.e.l.ls, and under this 2 feet of gravel, in which the shaped flints were found generally at the rate of 5 or 6 in a square yard. In the sandy beds with sh.e.l.ls were found the jawbone and teeth of an enormous unknown animal. The manner in which the flint weapons lay would lead to the persuasion that it was a place of their manufacture, and not of their accidental deposit. Their numbers were so great that the man who carried on the brick-work told me that before he was aware of their being objects of curiosity, he had emptied baskets full of them into the ruts of the adjoining road."