Geological Evidences of the Antiquity of Man/Chapter 6

by Charles Lyell

 

CHAPTER VI.

POST-PLIOCENE ALLUVIUM AND CAVE DEPOSITS WITH FLINT IMPLEMENTS.

GENERAL POSITION OF DRIFT WITH EXTINCT MAMMALIA IN VALLEYS—DISCOVERIES OF M. BOUCHER DE PERTHES AT ABBEVILLE—FLINT IMPLEMENTS FOUND ALSO AT ST. ACHEUL, NEAR AMIENS—CURIOSITY AWAKENED BY THE SYSTEMATIC EXPLORATION OF THE BRIXHAM CAVE—FLINT KNIVES IN SAME, WITH BONES OF EXTINCT MAMMALIA—SUPER-POSITION OF DEPOSITS IN THE CAVE—VISITS OF ENGLISH AND FRENCH GEOLOGISTS TO ABBEVILLE AND AMIENS.

 

Post-pliocene Alluvium containing Flint Implements in the Valley of the Somme.

THROUGHOUT a large part of Europe we find at moderate elevations above the present river-channels, usually at a height of less than forty feet but sometimes much higher, beds of gravel, sand, and loam containing bones of the elephant, rhinoceros, horse, ox, and other quadrupeds, some of extinct, others of living, species, belonging for the most part to the fauna already alluded to in the last chapter as characteristic of the interior of caverns. The greater part of these deposits contain fluviatile shells, and have undoubtedly been accumulated in ancient river-beds. These old channels have long since been dry, the streams which once flowed in them having shifted their position, deepening the valleys, and often widening them on one side.

It has naturally been asked, if man coexisted with the extinct species of the caves, why were his remains and the works of his hands never embedded outside the caves in ancient river-gravel containing the same fossil fauna? Why should it be necessary for the geologist to resort for evidence of the antiquity of our race to the dark recesses of underground vaults and tunnels, which may have served as places of refuge or sepulture to a succession of human beings and wild animals, and where floods may have confounded together in one breccia the memorials of the fauna of more than one epoch? Why do we not meet with a similar assemblage of the relics of man, and of living and extinct quadrupeds, in places where the strata can be thoroughly scrutinised in the light of day?

Recent researches have at length demonstrated that such memorials, so long sought for in vain, do in fact exist, and their recognition is the chief cause of the more favourable reception now given to the conclusions which MM. Tournal, Christol, Schmerling, and others, arrived at thirty years ago respecting the fossil contents of caverns.

The first great step in this new direction was made thirteen years after the publication of Schmerling's 'Researches,' by M. Boucher de Perthes, who found in ancient alluvium at Abbeville, in Picardy, some flint implements, the relative antiquity of which was attested by their geological position. The antiquarian knowledge of their discoverer enabled him to recognise in their rude and peculiar type a character distinct from that of the polished stone weapons of a later period, usually called 'celts.' In the first volume of his 'Antiquités Celtiques,' published in 1847, M. Boucher de Perthes styled these older tools 'antediluvian,' because they came from the lowest beds of a series of ancient alluvial strata bordering the valley of the Somme, which geologists had termed 'diluvium.' He had begun to collect these implements in 1841, from which time they had been dug out of the drift or deposits of gravel and sand whenever excavations were made in repairing the fortifications of Abbeville; or annually, as often as flints were wanted for the roads, or loam for making bricks. Fine sections, therefore, were laid open, from twenty to thirty-five feet in depth, and the bones of quadrupeds of the genera elephant, rhinoceros, bear, hyæna, stag, ox, horse, and others, were found, and had been sent from time to time to Paris to be examined and named by Cuvier, who described them in his 'Ossements Fossiles.' A correct account of the associated flint tools and of their position was given in 1847 by M. Boucher de Perthes in his work above cited, and they were stated to occur at various depths, often twenty or thirty feet from the surface, in sand and gravel, especially in those strata which were nearly in contact with the subjacent white chalk. But the scientific world had no faith in the statement that works of art, however rude, had been met with in undisturbed beds of such antiquity. Few geologists visited Abbeville in winter, when the sand-pits were open, and when they might have opportunities of verifying the sections, and judging whether the instruments had really been embedded by natural causes in the same strata with the bones of the mammoth, rhinoceros, and other extinct mammalia. Some of the tools figured in the 'Antiquités Celtiques' were so rudely shaped, that many imagined them to have owed their peculiar forms to accidental fracture in a river's bed; others suspected frauds on the part of the workmen, who might have fabricated them for sale, or that the gravel had been disturbed, and that the worked flints had got mingled with the bones of the mammoth long after that animal and its associates had disappeared from the earth.

No one was more sceptical than the late eminent physician of Amiens, Dr. Rigollot, who had long before (in the year 1819) written a memoir on the fossil mammalia of the valley of the Somme. He was at length induced to visit Abbeville, and, having inspected the collection of M. Boucher de Perthes, returned home resolved to look for himself for flint tools in the gravel-pits near Amiens. There, accordingly, at a distance of about forty miles from Abbeville, he immediately found abundance of similar flint implements, precisely the same in the rudeness of their make, and the same in their geological position; some of them in gravel nearly on a level with the Somme, others in similar deposits resting on chalk at a height of about ninety feet above the river.

Dr. Rigollot having in the course of four years obtained several hundred specimens of these tools, most of them from St. Acheul in the south-east suburbs of Amiens, lost no time in communicating an account of them to the scientific world, in a memoir illustrated by good figures of the worked flints and careful sections of the beds. These sections were executed by M. Buteux, an engineer well qualified for the task, who had written a good description of the geology of Picardy. Dr. Rigollot, in this memoir, pointed out most clearly that it was not in the vegetable soil, nor in the brick-earth with land and fresh-water shells next below, but in the lower beds of coarse flint-gravel, usually twelve, twenty, or twenty-five feet below the surface, that the implements were met with, just as they had been previously stated by M. Boucher de Perthes to occur at Abbeville. The conclusion, therefore, which was legitimately deduced from all the facts, was that the flint tools and their fabricators were coeval with the extinct mammalia embedded in the same strata.

 

Brixham Cave, near Torquay, Devonshire.

Four years after the appearance of Dr. Rigollot's paper, a sudden change of opinion was brought about in England respecting the probable coexistence, at a former period, of man and many extinct mammalia, in consequence of the results obtained from a careful exploration of a cave at Brixham, near Torquay, in Devonshire. As the new views very generally adopted by English geologists had no small influence on the subsequent progress of opinion in France, I shall interrupt my account of the researches made in the Valley of the Somme, by a brief notice of those which were carried on in 1858 in Devonshire with more than usual care and scientific method. Dr. Buckland, in his celebrated work, entitled 'Reliquiæ Diluvianæ,' published in 1823, in which he treated of the organic remains contained in caves, fissures, and 'diluvial gravel' in England, had given a clear statement of the results of his own original observations, and had declared that none of the human bones or stone implements met with by him in any of the caverns could be considered to be as old as the mammoth and other extinct quadrupeds. Opinions in harmony with this conclusion continued until very lately to be generally in vogue in England; although about the time that Schmerling was exploring the Liége caves, the Rev. Mr. M'Enery, a Roman Catholic priest, residing near Torquay, had found in a cave one mile east of that town, called 'Kent's Hole,' in red loam covered with stalagmite, not only bones of the mammoth, tichorhine rhinoceros, cave-bear, and other mammalia, but several remarkable flint tools, some of which he supposed to be of great antiquity, while there were also remains of man in the same cave of a later date.^[1]

About ten years afterwards, in a 'Memoir on the Geology of South Devon,' published in 1842 by the Geological Society of London,^[2] an able geologist, Mr. Godwin-Austen, declared that he had obtained in the same cave (Kent's Hole) works of man from undisturbed loam or clay, under stalagmite, mingled with the remains of extinct animals, and that all these must have been introduced 'before the stalagmite flooring had been formed.' He maintained that such facts could not be explained away by the hypothesis of sepulture, as in Dr. Buckland's well-known case of the human skeleton of Paviland, because in the Devon cave the flint implements were widely distributed through the loam, and lay beneath the stalagmite.

As the osseous and other contents of Kent's Hole had, by repeated diggings, been thrown into much confusion, it was thought desirable in 1858, when the entrance of a new and intact bone-cave was discovered at Brixham, three or four miles west of Torquay, to have a thorough and systematic examination made of it. The Royal Society made two grants towards defraying the expenses,^[3] and a committee of geologists was charged with the investigations, among whom Mr. Prestwich and Dr. Falconer took an active part, visiting Torquay while the excavations were in progress under the superintendence of Mr. Pengelly. The last-mentioned geologist had the kindness to conduct me through the subterranean galleries after they had been cleared out in 1859; and I saw, in company with Dr. Falconer, the numerous fossils which had been taken from the subterranean fissures and tunnels, all labelled and numbered, with references to a journal kept during the progress of the work, and in which the geological position of every specimen was recorded with scrupulous care.

The discovery of the existence of this suite of caverns near the sea at Brixham was made accidentally by the roof of one of them falling in. None of the five external openings now exposed to view in steep cliffs or the sloping side of a valley were visible before the breccia and earthy matter which blocked them up were removed during the late exploration. According to a ground-plan drawn up by Professor Ramsay, it appears that some of the passages which run nearly north and south are fissures connected with the vertical dislocation of the rocks, while another set, running nearly east and west, are tunnels, which have the appearance of having been to a great extent hollowed out by the action of running water. The central or main entrance, leading to what is called the 'reindeer gallery,' because a perfect antler of that animal was found sticking in the stalagmitic floor, is ninety-five feet above the level of the sea, being also about sixty above the bottom of the adjoining valley. The united length of the five galleries which were cleared out amounted to several hundred feet. Their width never exceeded eight feet. They were sometimes filled up to the roof with gravel, bones, and mud, but occasionally there was a considerable space between the roof and floor. The latter, in the case of the fissure-caves, was covered with stalagmite, but in the tunnels it was usually free from any such incrustation. The following was the general succession of the deposits forming the contents of the underground passages and channels:—

1st. At the top, a layer of stalagmite varying in thickness from one to fifteen inches, which sometimes contained bones, such as the reindeer's horn, already mentioned, and an entire humerus of the cave-bear.

2ndly. Next below, loam or bone-earth, of an ochreous red colour, from one foot to fifteen feet in thickness.

3rdly. At the bottom of all, gravel with many rounded pebbles in it, probed in some places to the depth of twenty feet without its being pierced through, and as it was barren of fossils, left for the most part unremoved.

The mammalia obtained from the bone-earth consisted of Elephas primigenius, or mammoth ; Rhinoceros tichorhinus; Ursus spelæus; Hyæna spelæa; Felis spelæa, or the cave-lion; Cervus Tarandus, or the reindeer; a species of horse, ox, and several rodents, and others not yet determined.

No human bones were obtained anywhere during these excavations, but many flint knives, chiefly from the lowest part of the bone-earth; and one of the most perfect lay at the depth of thirteen feet from the surface, and was covered with bone-earth of that thickness. From a similar position was taken one of those siliceous nuclei, or cores, from which flint flakes had been struck off on every side. Neglecting the less perfect specimens, some of which were met with even in the lowest gravel, about fifteen knives, recognised as artificially formed by the most experienced antiquaries, were taken from the bone-earth, and usually from near the bottom. Such knives, considered apart from the associated mammalia, afford in themselves no safe criterion of antiquity, as they might belong to any part of the age of stone, similar tools being sometimes met with in tumuli posterior in date to the era of the introduction of bronze. But the anteriority of those at Brixham to the extinct animals is demonstrated not only by the occurrence at one point in overlying stalagmite of the bone of a cave-bear, but also by the discovery at the same level in the bone-earth, and in close proximity to a very perfect flint tool, of the entire left hind-leg of a cave-bear. This specimen, which was shown me by Dr. Falconer and Mr. Pengelly, was exhumed from the earthy deposit in the reindeer gallery, near its junction with the flint-knife gallery, at the distance of about sixty-five feet from the main entrance. The mass of earth containing it was removed entire, and the matrix cleared away carefully by Dr. Falconer in the presence of Mr. Pengelly. Every bone was in its natural place, the femur, tibia, fibula, ankle-bone, or astragalus, all in juxta-position. Even the patella or detached bone of the knee-pan was searched for, and not in vain. Here, therefore, we have evidence of an entire limb not having been washed in a fossil state out of an older alluvium, and then swept afterwards into a cave, so as to be mingled with flint implements, but having been introduced when clothed with its flesh, or at least when it had the separate bones bound together by their natural ligaments, and in that state buried in mud.

If they were not all of contemporary date, it is clear from this case, and from the humerus of the Ursus spelæus, before cited, as found in a floor of stalagmite, that the bear lived after the flint tools were manufactured, or in other words, that man in this district preceded the cave-bear.

A glance at the position of the Brixham limestone containing the ossiferous caverns and fissures, and a brief survey of the valleys which bound it on two sides, are enough to satisfy a geologist that the drainage and geographical features of this region have undergone great changes since the gravel and bone-earth were carried by streams into the subterranean cavities above described. Some worn pebbles of hematite, in particular, can only have come from their nearest parent rock, at a period when the valleys immediately adjoining the caves were much shallower than they now are. The reddish loam in which the bones are embedded is such as may be seen on the surface of limestone in the neighbourhood, but the currents which were formerly charged with such mud must have run at a level sixty feet above that of the stream now flowing in the same valley. It was remarked by Mr. Pengelly, that the pebbles in the gravel and the bones in the loam had their longer axes parallel to the direction of the tunnels and fissures, showing that they were deposited by the action of a stream.

It appears that so long as the flowing water had force enough to propel stony fragments, no layer of fine mud could accumulate, and so long as there was a regular current capable of carrying in fine mud and bones, no superficial crust of stalagmite. In some passages, as before stated, stalagmite was wanting, while in one place five alternations of stalagmite and sand were observed, seeming to indicate a prevalence of more rainy seasons, succeeded by others, when the water was for a time too low to flood the area where the calcareous incrustation accumulated.

If the regular sequence of the three deposits of pebbles, mud, and stalagmite was the result of the causes above explained, the order of superposition would be constant, yet we could not be sure that the gravel in one passage might not sometimes be coeval with the bone-earth or stalagmite in another.

If therefore the flint knives had not been very widely dispersed, and if one of them had not been at the bottom of the bone-earth, close to the leg of the bear above described, their antiquity relatively to the extinct mammalia might have been questioned. No coprolites were found in the Brixham excavations, and very few gnawed bones. These few may have been brought from some distance, before they reached their place of rest. Upon the whole, the same conclusion which Dr. Schmerling came to, respecting the filling up of the caverns near Liége, seems applicable to the caves of Brixham.

Dr. Falconer, after aiding in the investigations above alluded to near Torquay, stopped at Abbeville on his way to Sicily, in the autumn of 1858, and saw there the collection of M. Boucher de Perthes. Being at once satisfied that the flints called hatchets had really been fashioned by the hand of man, he urged Mr. Prestwich, by letter, thoroughly to explore the geology of the Valley of the Somme. This he accordingly accomplished, in company with Mr. John Evans, of the Society of Antiquaries, and, before his return that same year, succeeded in dissipating all doubts from the minds of his geological friends by extracting, with his own hands, from a bed of undisturbed gravel, at St. Acheul, a well-shaped flint hatchet. This implement was buried in the gravel at a depth of seventeen feet from the surface, and was lying on its flat side. There were no signs of vertical rents in the enveloping matrix, nor in the overlying beds of sand and loam, in which were many land and fresh-water shells; so that it was impossible, to imagine that the tool had gradually worked its way downwards, as some had suggested, through the incumbent soil, into an older formation.^[4]

There was no one in England whose authority deserved to have more weight in overcoming incredulity in regard to the antiquity of the implements in question than that of Mr. Prestwich, since, besides having published a series of important memoirs on the tertiary formations of Europe, he had devoted many years specially to the study of the drift and its organic remains. His report, therefore, to the Royal Society, accompanied by a photograph showing the position of the flint tool in situ before it was removed from its matrix, not only satisfied many inquirers, but induced others to visit Abbeville and Amiens; and one of these, Mr. Flower, who accompanied Mr. Prestwich on his second excursion to St. Acheul, in June 1859, succeeded, by digging into the bank of gravel, in disinterring, at the depth of twenty-two feet from the surface, a fine, symmetrically shaped weapon of an oval form, lying in and beneath strata which were observed by many witnesses to be perfectly undisturbed.^[5]

Shortly afterwards, in the year 1859, I visited the same pits, and obtained seventy flint tools, one of which was taken out while I was present, though I did not see it before it had fallen from the matrix. I expressed my opinion in favour of the antiquity of the flint tools to the meeting of the British Association at Aberdeen, in the same year.^[6] On my way through Rouen, I stated my convictions on this subject to Mr. George Pouchet, who immediately betook himself to St. Acheul, commissioned by the municipality of Rouen, and did not quit the pits till he had seen one of the hatchets extracted from gravel in its natural position.^[7]

M. Gaudry also gave the following account of his researches in the same year to the Royal Academy of Sciences at Paris. 'The great point was not to leave the workmen for a single instant, and to satisfy oneself by actual inspection, whether the hatchets were found in situ. I caused a deep excavation to be made, and found nine hatchets, most distinctly in situ in the diluvium, associated with teeth of Equus fossilis and a species of Bos, different from any now living, and similar to that of the diluvium and of caverns.'^[8] In 1859, M. Hébert, an original observer of the highest authority, declared to the Geological Society of France that he had, in 1854, or four years before Mr. Prestwich's visit to St. Acheul, seen the sections at Abbeville and Amiens, and had come to the opinion that the hatchets were imbedded in the 'lower diluvium,' and that their origin was as ancient as that of the mammoth and the rhinoceros. M. Desnoyers also made excavations after M. Gaudry, at St. Acheul, in 1859, with the same results.^[9]

After a lively discussion on the subject in England and France, it was remembered, not only that there were numerous recorded cases leading to similar conclusions in regard to cavern deposits, but, also, that Mr. Frere had, so long ago as 1797, found flint weapons, of the same type as those of Amiens, in a fresh-water formation in Suffolk, in conjunction with elephant remains; and nearly a hundred years earlier (1715), another tool of the same kind had been exhumed from the gravel of London, together with bones of an elephant; to all which examples I shall allude more fully in the sequel.

I may conclude this chapter by quoting a saying of Professor Agassiz, 'that whenever a new and startling fact is brought to light in science, people first say, "it is not true," then that "it is contrary to religion," and lastly, "that every body knew it before."'

If I were considering merely the cultivators of geology, I should say that the doctrine of the former co-existence of man with many extinct mammalia had already gone through these three phases in the progress of every scientific truth towards acceptance. But the grounds of this belief have not yet been fully laid before the general public, so as to enable them fairly to weigh and appreciate the evidence. I shall therefore do my best in the next three chapters to accomplish this task.

1. The MS. and plates prepared for a joint memoir on Kent's Hole, by Mr. M'Enery and Dr. Buckland, have recently been published by Mr. Vivian of Torquay, from which, as well as from some of the unprinted MS., I infer that Mr. M'Enery only refrained out of deference to Dr. Buckland from declaring his belief in the contemporaneousness of certain flint implements of an antique type and the bones of extinct animals. Two of these implements from Kent's Hole, figured in Plate 12 of the posthumous work above alluded to, approach very closely in form and size to the common Abbeville implements.
2. Transactions of Geological Society, 2nd series, vol. vi. p. 444.
3. When these grants failed, Miss Burdett Coutts, then residing at Torquay, liberally supplied the funds for completing the work.
4. Prestwich, Proceedings of the Royal Society, 1859, and Philosophical Transactions, 1860.
5. Geological Quarterly Journal, vol. xvi. p. 190.
6. See Proceedings of British Association for 1859.
7. Actes du Musée d'Histoire Naturelle de Rouen, 1860, p. 33.
8. Comptes rendus, September 26th, and October 3rd, 1859.
9. Bulletin, vol. xvii. p. 18.