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ADVANTAGES AND DISADVANTAGES OF DETECTION
MAGNETIC IN ARCHAEOLOGICAL EXCAVATION
FOREWORD
I would like first of all to thank Mr. STRAINER, SMALL Mr. and Mr. GERARD For the confidence which they agreed to testify to me while enabling me to work in full collaboration with them in a speciality if décriée: electromagnetic detection.
INTRODUCTION
For eleven years that I practise electromagnetic detection, I have especially learned how to discover new advantages, new applications to the service of archaeology and not of the disadvantages.
However, these disadvantages exist.
Most significant and denounced extremely precisely by you all, it is the " clandestinage ".
The second major disadvantage is in my opinion the not structured use, nonrational of the detector.
I will first of all point out the current legislation as regards electromagnetic detection, then I will develop the various advantages through a number of examples lived as well as regards prospection as of excavation.
Lastly, with the risk to displease or shock, I will try some proposals which seem to me likely to cure on the one hand the " clandestinage ", and on the other hand to serve the archaeological cause in parallel.
THE LEGISLATION
AS REGARDS METAL DETECTORS
The law of December 18, 1989 relating to the use of the metal detectors specifies in its article 1 : " No one cannot use hardware allowing the metal target detection, with the effect of search of monuments and objects being able to interest prehistory, the history, art or archaeology, without having with the precondition, obtained an administrative authorisation delivered according to the qualification of the applicant as well as nature and methods of search."
A recent decree of August 19, 1991 supplements this law in its title first, article 1: " the authorization to use hardware allowing the metal target detection, envisaged the article le' of the law of December 18, 1989, is granted, on request of the interested party, by decree of the Prefect of the Area in which is located the ground to be prospected "
The request d?autorisation specifies l?identity, competences and the experiment of its author as well as the localization, the scientific objective and the duration of the prospections to be undertaken.
When the prospections must be carried out on a ground not belonging to the author of the request, this last must join to its file the written assent of the owner of the ground and, if it is necessary, that of very other having right
The decree granting the authorization fixes the conditions according to which the prospections will have to be led.
When the holder of an authorization does not comply with the regulations of them, the Prefect of Area pronounces the withdrawal of the authorization.
In connection with this new provision, I make a point of expressing my concern about the heaviness of this procedure which delays the interventions on the ground.
Within the framework of excavations or rescues, can't one consider that the authorizations of the owners of the grounds are obligatorily delivered before the opening of search and that in these precise cases, only the agreement of the Director of Historical Antiquities is enough for the use of the detector on these building sites, agreement endorsed later on if necessary by the Prefect according to legal provisions'?
On the other hand, within the framework of the prospections, I find this provision, though constraining, completely justified; it indeed obliges to plan a long time in advance the prospections considered because it is not rare in rural medium that multiple contiguous pieces are distributed between many owners and operators.
Force is to note that the law in this field did not dissuade and will not dissuade the " frying pans clandestine " to beat the countryside, and even to briskly furrow the declared sites, when they are not installed on a building site in the course of excavation.
Then, as it is not possible to d?obtenir authorizations easily, I will recommend that each association, entitled following the example GERAME, has a section " PROSPECTION-DÉTECTION -, realising of course the adhesion of prospectors " of good morality " which it will rest to the presidents of association to or not approve.
To avoid any overflow, only the person in charge of this section and its substitute would be provided with enabling together with authorizations with the S.R.A., and now of the Prefect, clean with each prospection considered.
That supposes, of course, that the person in charge and his substitute have themselves a sufficient knowledge as regards archaeological excavation in order to form and to sensitize the members of their section to the various aspects of the prospection.
These sections being thus made up, it matters that they do not disperse in isolated actions but that on the contrary, they act according to a well structured program comprising at the same time operations of prospection, rescue or excavation.
POSSIBILITIES AND ADVANTAGES OF THE METAL DETECTOR
With - prospection
In order to eliminate the clandestine prospectors, a systematic prospection of all the currently known sites should be made in a methodical way, intended to establish on plan a detailed inventory of the lucky finds carried out.
These inventories will be placed later on at the disposal of any programmed excavation have suddenly opened on the spot.
In addition to the prevention on the already known sites, the electromagnetic prospection lays down other objectives
1 - It makes it possible to specify the nature and the dating of the known sites, thanks to a more complete and more detailed inventory of the objects being attached to it.
2 - It also makes it possible to make the follow-up of the sites:
Indeed, each ploughing brings on the surface new elements. A passage of the subsoil plough, large destroying of sites, is even more spectacular and allowed me to detect for example on the commune of Corers IV century a monetary deposit.
3 - In end, it allows the localization of new sites:
That supposes the methodical study of cards IGN to the 1/25000 ', as well in the field of topography as on that of toponymy. Thus the toponym " the Hovel " indicating very often the presence of ancient sites enabled us to locate in Mondeville various very wide habitats.
In this precise case, the pottery was very fragmented and not very abundant but electromagnetic detection allowed us, thanks to a number of quite localised currencies, to distinguish on plan in waiting from a possible excavation 4 different sectors
- a Gallic zone;
- II 2nd century a Gallo-Roman zone;
- IV 2nd century a Gallo-Roman zone;
- a zone carolingienne and medieval.
This activity of prospection thus proves very positive as regards prevention as within the framework of the establishment and the refinement of the data of the archaeological card.
B - the rescue
If it is a sector where the metal detector proves to be the essential ally of the archaeologist, it is well that of the excavation of rescue, since it will intervene effectively while acting quickly to precede the clandestine ones, and by providing a number of very invaluable elements to determine the nature and the dating of the site: sparse currencies or monetary deposits, different standard from fibules, deposits of weapons, tools or objects various...
A very recent example illustrates l?intérêt well detector in excavation of rescue - it is about the site of Chardonnière, with SaintPierre-of-Perray Or I intervened after scouring by the mechanical machines. The site really seemed to be limited to a zone very flush in its right part and the rescue to arrive at its end when the distribution of the currencies to the periphery of the site encouraged me to continue in a more insistent way my investigations in the left part then covered by enormous hillocks of fill. A very significant and major echo with the edge of these hillocks enabled us first of all to put at the day a strainer with wine out of bronze archaeologically complete, similar to that found in Mureaux and preserved at the museum of Guiry-in-Vexin, lucky find followed soon of a whole of iron attachment of several tens of kilos, like numbers various potteries, for the majority whole and broken on the spot.
We then decided to make remove the hillocks by the machines, which enabled us to put at the day initially a significant furniture, including 140 currencies, as well as the walls of the habitat and various very dense pits in hardware...
C - the excavation
Many examples of the utility of the detector can be evoked. They vary of course according to the type of excavation, according to its extent, its duration and the type of excavated ground.
I propose three well structured interventions and quite as necessary.
Before the excavation
- systematic Prospection of surface of all the zone to be excavated after scouring, with collection of the localised elements and pointing for localization on plan.
Numbers among you will be against this practice until the day when, having received the visit of clandestine, they will know frustration and the vain revolt which the vision of an open hole dug with the haste generates and which one is unaware of the contents.
During the excavation
systematic passage every five centimetres in order to perceive the echoes of very small elements such as jewels, refuse, nails of shoe, etc.
The attention of the digger is then mobilized; it knows that there is a metal element whose nature is given in advance (ferrous ore or not!)
The object localised remains in place; the digger will take it after estimate of the context of the lucky find.
In the fragile case of objects (currencies, fibules, sculptor, tools, etc), it is an additional guarantee of safeguarding.
A particular application of the detector is illustrated in the excavation of the necropoles.
The example was provided to me by the excavation of the necropolis of Chantambre with Buno-Bonnevaux, carried out by Mr. Louis GIRARD, and to which I was likely to take part during a few years.
Without revealing all the secrecies of the search carried out by Mr. GIRARD, I would say that apart from the burials innovations carried out in earthenware jars or half-earthenware jars, crémations (only one funeral urn out of glass at the time of my participation), of the thrown bodies, the whole of the burials is made up either of bodies deposited on stretchers, in great majority, or of bodies deposited in coffins.
In these the last two cases, the nails fixing either the elements of the coffin, or the elements of the stretcher are determining, all the woodworks having obviously disappeared.
At the time, there were already 600 or 700 tombs going of 0,50m with 2,50m of depth; however, one cannot reasonably descend 2,50 m to the trowel, even if it is in sand by 600 or 700 times, therefore preliminary descent to the shovel and the spade.
Then appears the dark spot indicating the embankment of the tomb. The detector passed in this ground regularly flat every 15 cm makes it possible to immediately check the alignments of nails which one then releases carefully with the trowel. It is thus easy to distinguish the coffins with a first level from nails, head in top, point in bottom.
For the stretchers, the perception of the nails on the second level has an additional role of safeguarding of furniture.
Even localised, nothing is easy any more to make " valser " than a nail and yet the statistical interest between a number of coffins and a number of stretchers is not to neglect.
Still in Chantambre, it was about sand; what becomes this first level of nails in an excavation on the compact ground, brittle or sticking?
After the excavation:
Once made the preliminary prevention and the localization in the course of excavation, remains the ultimate checking: systematic prospection of spoil. I hear already the outcries of the diggers, forts of their experiment and sure of their?il of lynx: " a good digger should nothing let pass! "
If this remark is theoretically true and is essential on the spirit of the professional, it does not remain less true about it than reality on the ground is very different. That known as without wanting to wound nor to criticize anyone, force is to note that l??il and the human hand, was they professionals are far from being infallible! The many lucky finds carried out by my colleagues and myself on various building sites can only support my remarks.
This is why I invite the persons in charge of building sites archaeological wishing to associate with their search electromagnetic detection to avoid as far as possible the constitution of anarchistic cut heap, where one finds pêle-mixes, silver plated papers, cans and other objects...
Moreover, each cut heap will have to correspond to a " pointing " given (it is an element of welding, A 1, A 2, etc; it is a bottom of hut, it is a pit, etc).
It is advisable to consider that certain grounds are more difficult than others to excavate. In addition to the fact that a digger remains a Man and that in spite of its experiment, tiredness helping, its attention can be sometimes slackened, we could note that the grounds with ground very fatty or argillaceous, either too wet, or too dry, and even fillings brittle and wet are particularly favourable with the rejection in spoil of very interesting elements (small ferrous tools, currencies, fibules, etc).
In these grounds, sifting is impossible, except under the effect of a water jet, but still takes it much water and time.
In the very dry grounds fatty, it would be necessary to break the mounds one by one, which is practically impossible for the same reasons as above.
In the very wet fatty grounds, you have nine risks out of ten to let pass a number of objects.
A characteristic still arises with is very brittle and wet.
Indeed, the metal objects subjected to the acidity of this type of ground are coated in a true very hard gangue which outside presents a perfect analogy with self in which they were, which encourages to confuse them with a mound of hardened ash or a slag. In fact, the objects, removed from this gangue, prove preserved often well.
For example, in Saint-Germain-les-Corbeil, spoil resulting from the filling of the Gallo-Roman cellar delivered tens of currencies of the IV 2nd century beginning, just as those coming from the filling of a large pit of, century, where two were found fibules.
A last detail to be announced
- when you release well the flush walls of your Gallo-Roman habitat, that last statements and stereotypes will have been carried out, and right before the bulldozers do not come forever to stripe card the object of your excavation, thus dare to let slip the pallet of the detector of service on these last vestiges and perhaps you will have the joy, as in Saint-Germain-les-Corbeil, to discover under the stones, in the angle formed by two walls, a small monetary deposit D foundation, of which the importance For the dating will be appropriate to you about it, Cannot be denied.
PROPOSALS TO CURE
WITH the " clandestinage " AND TO REINFORCE the ROWS OF the VOLUNTARY ones
We saw the principle of the sections previously " prospection-detection " inside the archaeological groups.
I would sincerely hope to widen these sections with those which one calls overall the clandestine ones, which sin for the majority more by ignorance and exclusion that by real lure of gain.
There are currently approximately 100000 owners of metal detectors; for me, they are 100000 potential diggers if one wants to practise well the opening, the tolerance and especially information.
Currently I have the impression that one gives oneself good conscience while cutting off oneself behind a law.
However, since these laws exist, the " clandestinage ", continues and will continue and this, for two imperative reasons: - the principal one, it is passion, the taste of search and the joy of the discovery, as many aptitudes which are appropriate with wonder with archaeology.
- the second, more terre.à.terre, is that a detector the top-of-the-range one is very expensive (approximately 10 000 F today), and that the prospector dreams, without believing in it too much besides, that it will be able to attenuate or deaden by his lucky finds, the cost of its acquisition.
. I have noted for ten years that by refusal to dialogue, to seek a compromise solution which would satisfy all the parts, numbers discoveries have escaped and will still escape knowledge from all.
How many wonders sleep in the drawers and the wall cupboards of private collections because there is no alternative?
How many Gallic sites were thus localised for example in forest of Sénart; however only the currencies and the fibules, even the weapons, made it possible to indicate precisely the existence of these sites because the thick layer of humus makes them invisible to the visual prospection.
For some currencies to be declared, in fact thus the the corresponding sites escape knowledge, their localization not being able more to be carried out from now on but in a fortuitous way, during work.
Then to the risk to shock a number among you, I think that while agreeing " to give " a little, our inheritance, in the field of the archaeological discoveries, would gain there much.
It would gain there also certainly in the field of the reinforcements brought to the rows of voluntary and not only within the skimped framework of the only electromagnetic detection.
I am myself come with archaeology by electromagnetic detection and I remain persuaded whom a number of those which one calls the clandestine ones tomorrow will be impassioned diggers if one practises information, the formation and the opening.
Here thus the proposals which I dare to put forth before this assembly:
- it is first of all advisable to regulate and control the use of these apparatuses. Thus, the prospector using a metal detector, will have obligatorily to thus adhere to a competent archaeological association, comprising a section of search practising electromagnetic detection;
- the person in charge of this section will hold a file of the participating members; this last will be communicated like its update with the S.R.A. area Island-of-France;
- only, the person in charge of the local section as his substitute will be sworn in and will be able to have a legal authorization to present. if necessary, with the local authorities;
- a preliminary knowledge of the techniques of excavation will have to be comparable before the practice on the ground; that will suppose before any adhesion, the participation attested in various building sites of excavation;
- before the one year beginning of prospection, a list of the various research projects under consideration for the season, comprising the precise co-ordinates of cards IGN concerned, will have to be subjected for the examination by the S.R.A. by each person in charge of section.
In return, the lists will be supplemented by an agreement or a refusal according to cases', and will mention in particular, if it is about a site already declared or not.
However, these lists are not exhaustive and could be matched special permits at the time of specific cases of fortuitous discovery or search of rescue, for example, requiring an urgent intervention.
The participants commit themselves declaring systematically, under cover of the person in charge or of its substitute, all the discoveries carried out, namely:
- descriptive sheet of the site (with photocopy card IGN)
- detailed report/ratio
- all elements collected: various potteries, metal elements (tools, crockery, currencies, etc), fragments of glass, bones, tools lithic...
Any failure with these principles will involve the final exclusion of the faulty member of the local section, notwithstanding the lawful continuations.
With regard to the devolution of the discovered objects, three cases are to be considered:
1 - The S.R.A. requires the intervention on a presumption of site or on a declared site but comprising an insufficient number of elements:
The totality of the lucky finds carried out returns from right to the S.R.A.
2 - The section, local discovers a new site not indexed:
It is famous inventor of this discovery. The declaration of site is carried out under the usual conditions. The totality of the lucky finds is given to the S.R.A. for examination and inventory; this placing on tip will not be able to exceed two years. The local section can assert for the famous objects of value and particularly for the currencies, the statute of inventor. According to the legislation currently in force for the discoveries of treasure, the inventor, provided that it obtained the agreement of the owner of the places, is famous to be entitled to half of the value of his lucky find, other half being allocated to the owner. With the exit of the two years above mentioned deadline, the discoveries are placed at the disposal of the inventor and the owner.
In the event of sale, the State will be able to exert, as with accustomed, its right of pre-emption.
The methods of distribution between the members of each section of the product of the sale, if necessary, could take as a starting point the the following essential criteria: - 50% for the owner of the places, - 10% for the archaeological group on which the section depends,
- 10 % would be intended to the effective author of the lucky find on the ground, - the 30% remainder would be distributed equally between all the members of the section, including the author of the lucky find referred to above, but accompanied with a coefficient of assiduity at the exits carried out making it possible to ensure a maximum of participation.
3 - Case of a fortuitous lucky find not having any relationship with the site itself (deposit isolated from any context or lost object):
- that search takes place near a site declared or not, the section carrying out the lucky find can assert the invention of it;
- example: following a request for control on a Gallo-Roman site, a prospector discovers near the site, a deposit of the time napoléonienne!
This proposal of statute presents, for the whole of the parts, various advantages.
For the S.R.A. - availability of a quota of some 100000 voluntary Potential diggers;
