118

THEIR FORMS AND GREAT NUMBERS.

CHAP. VII.

from a pit which I caused to be dug at Abbeville, in sand in contact with the chalk, and below certain fluvio-marine beds, which will be alluded to in the next chapter.

Flint knife or flake from below the sand containing Cyrena fluminalis.
Menchecourt, Abbeville.

d Transverse section along the line of fracture, b, c.
Size, two-thirds of the original.

Between the spear-head and oval shapes, there are various intermediate gradations, and there are also a vast variety of very rude implements, many of which may have been rejected as failures, and others struck off as chips in the course of manufacturing the more perfect ones. Some of these chips can only be recognised by an experienced eye as bearing marks of human workmanship.

It has often been asked, how, without the use of metallic hammers, so many of these oval and spear-headed tools could have been wrought into so uniform a shape. Mr. Evans, in order experimentally to illustrate the process, constructed a stone hammer, by mounting a pebble in a wooden handle, and with this tool struck off flakes from the edge on both sides of a chalk flint, till it acquired precisely the same shape as the oval tool, fig. 9, p. 115.

If I were invited to estimate the probable number of the more perfect tools found in the valley of the Somme since 1842, rejecting all the knives, and all that might be suspected of being spurious or forged, I should conjecture that they far exceeded a thousand. Yet it would be a great mistake to imagine that an antiquary or geologist, who should devote a few weeks to the exploration of such a valley as that of the

CHAP. VII. GLOBULAR SPONGES ARTIFICIALLY PERFORATED.

119

Somme, would himself be able to detect a single specimen. But few tools were lying on the surface. The rest have been exposed to view by the removal of such a volume of sand, clay, and gravel, that the price of the discovery of one of them could only be estimated by knowing how many hundred labourers have toiled at the fortifications of Abbeville, or in the sand and gravel pits near that city, and around Amiens, for road materials and other economical purposes, during the last twenty years.

In the gravel pits of St. Acheul, and in some others near Amiens, small round bodies, having a tubular cavity in the centre, occur. They are well known as fossils of the white chalk. Dr. Rigollot suggested that they might have been

a,b Coscinopora globularis D'Orb. Orbitolina concava Parker and Jones. c Part of the same magnified.

strung together as beads, and he supposed the hole in the middle to have been artificial. Some of these round bodies are found entire in the chalk and in the gravel, others have naturally a hole passing through them, and sometimes one or two holes penetrating some way in from the surface, but not extending to the other side. Others, like b, fig. 15, have a large cavity, which has a very artificial aspect. It is impossible to decide whether they have or have not served as personal ornaments, recommended by their globular form, lightness, and by being less destructible than ordinary chalk. Granting that there were natural cavities in the axis of some of them, it does not follow that these may not have been taken advantage of for stringing them as beads, while others may have been artificially bored through. Dr. Rigollot's

120 GLOBULAR SPONGES ARTIFICIALLY PERFORATED. CHAP. VII.

argument in favour of their having been used as necklaces or bracelets, appears to me a sound one. He says he often found small heaps or groups of them in one place, all perforated, just as if, when swept into the river's bed by a flood, the bond which had united them together remained unbroken.*

* Rigollot, Mémoire sur des Instruments en Silex, &c. p. 16. Amiens, 1854.

CHAP. VIII. LOWER-LEVEL GRAVELS OF THE SOMME VALLEY.

121

CHAPTER VIII.

POST-PLIOCENE ALLUVIUM WITH FLINT IMPLEMENTS OF THE VALLEY OF THE SOMME,

IN

Concluded.

FLUVIO-MARINE STRATA, WITH FLINT IMPLEMENTS, NEAR ABBEVILLE
-MARINE SHELLS IN SAME CYRENA FLUMINALIS -MAMMALIA
ENTIRE SKELETON OF RHINOCEROS —— FLINT IMPLEMENTS, WHY FOUND
LOW DOWN IN FLUVIATILE DEPOSITS RIVERS SHIFTING THEIR
CHANNELS RELATIVE AGES OF HIGHER AND LOWER-LEVEL GRAVELS —
SECTION OF ALLUVIUM OF ST. ACHEUL-TWO SPECIES OF ELEPHANT
AND HIPPOPOTAMUS COEXISTING WITH MAN IN FRANCE VOLUME OF
DRIFT, PROVING ANTIQUITY OF FLINT IMPLEMENTS ABSENCE OF
HUMAN BONES IN TOOL-BEARING ALLUVIUM, HOW EXPLAINED — VALUE
OF CERTAIN KINDS OF NEGATIVE EVIDENCE TESTED THEREBY
HUMAN BONES NOT FOUND IN DRAINED LAKE OF HAARLEM.

N the section of the valley of the Somme, given at p. 106 (fig. 7), the successive formations newer than the chalk are numbered in chronological order, beginning with the most modern, or the peat, which is marked No. 1, and which has been treated of in the last chapter. Next in the order of antiquity are the lower-level gravels No. 2, which we have now to describe; after which the alluvium, No. 3, found at higher levels, or about eighty and one hundred feet above the river-plain, will remain to be considered.

I have selected, as illustrating the old alluvium of the Somme occurring at levels slightly elevated above the present river, the sand and gravel-pits of Menchecourt, in the northwest suburbs of Abbeville, to which, as before stated, p. 94, attention was first drawn by M. Boucher de Perthes, in his work on Celtic antiquities. Here, although in every adjoin

122

SECTION OF STRATA AT MENCHECOURT.

CHAP. VIII.

ing pit some minor variations in the nature and thickness of the superimposed deposits may be seen, there is yet a general approach to uniformity in the series. The only stratum of which the relative age is somewhat doubtful, is the gravel marked a, underlying the peat, and resting on the chalk. It is only known by borings, and some of it may be of the same age as No. 3; but I believe it to be for the most part of more modern origin, consisting of the wreck of all the older gravel, including No. 3, and formed during the last hollowing out

Section of fluvio-marine strata, containing flint implements and bones of extinct mammalia, at Menchecourt, Abbeville.*

1 Brown clay with angular flints, and occasionally chalk rubble, unstratified, following the slope of the hill, probably of subaerial origin, of very varying thickness, from two to five feet and upwards.

2 Calcareous loam, buff-coloured, resembling loess, for the most part unstratified, in some places with slight traces of stratification, containing freshwater and land shells, with bones of elephants, &c.; thickness about fifteen feet.

3 Alternations of beds of gravel, marl, and sand, with freshwater and land shells, and in some of the lower sands, a mixture of marine shells; also bones of elephant, rhinoceros, &c., and flint implements; thickness about twelve feet.

a Gravel underlying peat, age undetermined.

b Layer of impervious clay, separating the gravel from the peat.

and deepening of the valley immediately before the commencement of the growth of peat.

The greater number of flint implements have been dug out of No. 3, often near the bottom, and twenty-five, thirty, or even more than thirty feet below the surface of No. 1.

* For detailed sections and maps of this district, see Prestwich, Philosophical Transactions, 1860, p. 277.