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CHAP. VI. INVESTIGATIONS MADE AT ABBEVILLE AND AMIENS. 103

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.*

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.†

Shortly afterwards, in the year 1859, I visited the same pits, and obtained seventy flint tools, one of which was taken

* Prestwich, Proceedings of the Royal Society, 1859, and Philosophical Transactions, 1860.

+ Geological Quarterly Journal, vol. xvi. p. 190.

104

INVESTIGATIONS MADE AT ABBEVILLE AND AMIENS. CHAP. VI.

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."
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.†

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.' 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.§

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

* See Proceedings of British Association for 1859.

† Actes du Musée d'Histoire Naturelle de Rouen, 1860, p. 33.

Comptes rendus, September 26th,

and October 3rd, 1859.

8 Bulletin, vol. xvii. p. 18.

CHAP. VI. INVESTIGATIONS MADE AT ABBEVILLE AND AMIENS. 105

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 everybody 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.

106 GEOLOGICAL DESCRIPTION OF THE SOMME VALLEY. CHAP. VII.

CHAPTER VII.

PEAT AND POST-PLIOCENE ALLUVIUM OF THE VALLEY OF THE

SOMME.

GEOLOGICAL STRUCTURE OF THE VALLEY OF THE SOMME AND OF
THE SURROUNDING COUNTRY POSITION OF ALLUVIUM OF DIFFERENT
AGES PEAT NEAR ABBEVILLE-ITS ANIMAL AND VEGETABLE CON-
TENTS WORKS OF ART IN PEAT PROBABLE ANTIQUITY OF THE
PEAT, AND CHANGES OF LEVEL SINCE ITS GROWTH BEGAN - FLINT
IMPLEMENTS OF ANTIQUE TYPE IN OLDER ALLUVIUM — THEIR VARIOUS
FORMS AND GREAT NUMBERS.

TH

Geological Structure of the Somme Valley.

HE Valley of the Somme in Picardy, alluded to in the last chapter, is situated geologically in a region of white chalk with flints, the strata of which are nearly horizontal. The chalk hills which bound the valley are almost everywhere between 200 and 300 feet in height. On ascending to that elevation, we find ourselves on an extensive table-land, in which there are slight elevations and depressions. The white chalk itself is scarcely ever exposed at the surface on this plateau, although seen on the slopes of the hills, as at b and c (fig. 7). The general surface of the upland region is covered continuously for miles in every direction by loam or brick-earth (No.4), about five feet thick, devoid of fossils. To the wide extent of this loam the soil of Picardy chiefly owes its great fertility. Here and there we also observe, on the chalk, outlying patches of tertiary sand and clay (No. 5, fig. 7), with eocene fossils, the remnants of a formation once more extensive, and which probably once spread in one continuous mass over the chalk, before the present system of valleys had begun to be shaped out. It is necessary to allude to these relics of

CHAP. VII. GEOLOGICAL DESCRIPTION OF THE SOMME VALLEY. 107

tertiary strata, of which the larger part is missing, because their denudation has contributed largely to furnish the materials of gravels in which the flint implements and bones of extinct mammalia are entombed. From this source have been derived not only the regular-formed eggshaped pebbles, so common in the old fluviatile alluvium at all levels, but those huge masses of hard sandstone, several feet in diameter, to which I shall allude in the sequel. The upland loam also (No. 4) has often, in no slight degree, been formed at the expense of the same tertiary sands and clays, as is attested by its becoming more or less sandy or argillaceous, according to the nature of the nearest eocene outlier in the neighbourhood.

Chalk

Fig. 7.

Somme R.

Chalk

Section across the Valley of the Somme in Picardy.

1 Peat, twenty to thirty feet thick, resting on gravel, a.

2 Lower level gravel with elephants' bones and flint tools, covered with fluviatile loam, twenty to forty feet thick.

3 Upper level gravel with similar fossils, and with overlying loam, in all thirty feet thick.

4 Upland loam without shells (Limon des plateaux), five or six feet thick.

5 Eocene tertiary strata, resting on the chalk in patches.

The average width of the Valley of the Somme between Amiens and Abbeville is one mile. The height, therefore, of the hills, in relation to the river-plain, could not be correctly represented in the annexed diagram (fig. 7), as they would have to be reduced in altitude; or if not, it would be necessary to make the space between c and b four times as great. The dimensions also of the masses of drift or alluvium, 2 and 3, have been exaggerated, in order to render them sufficiently conspicuous; for, all important as we shall find them to be as geological monuments of the post-pliocene period, they form a truly insignificant feature in the general structure of

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