- P0/1 The corpus comprises 88 second Iron Age sites, all related to iron production activities, and divided into 7 categories
- P0/4 The slags, making up the greater part of iron-production waste, are classed into 7 categories depending on how they were formed
- P0/5 For the second Iron Age archaeological structures enable the iron production activities carried on in the workshops to be identified
- P0/12 Following the anthropological and experimental examples the chaîne opératoire in direct iron production may be divided into three major phases: reduction, refining, and object manufacture
- P0/1 The corpus comprises 88 second Iron Age sites, all related to iron production activities, and divided into 7 categories
- P0/4 The slags, making up the greater part of iron-production waste, are classed into 7 categories depending on how they were formed
- P0/7 The metallic elements can be separated into 6 categories
- P0/5 For the second Iron Age archaeological structures enable the iron production activities carried on in the workshops to be identified
- P0/12 Following the anthropological and experimental examples the chaîne opératoire in direct iron production may be divided into three major phases: reduction, refining, and object manufacture
- P0/1 The corpus comprises 88 second Iron Age sites, all related to iron production activities, and divided into 7 categories
- P0/4 The slags, making up the greater part of iron-production waste, are classed into 7 categories depending on how they were formed
- P0/7 The metallic elements can be separated into 6 categories
- P0/5 For the second Iron Age archaeological structures enable the iron production activities carried on in the workshops to be identified
- P0/12 Following the anthropological and experimental examples the chaîne opératoire in direct iron production may be divided into three major phases: reduction, refining, and object manufacture
- P0/6 The forge tools can be divided into two large families
- P0/17 Micrographic analysis of slag enables the chaînes opératoires be characterised
- P0/18 Metallographic analysis of the metallic elements enables the chaînes opératoires to be characterised
- P1/3 The whole chaîne opératoire was present on 9% of the sites
- P1/4 Post-reduction activities were present on 84% of the sites
- P2/3 The main post-reduction chaînes opératoires can be characterised
- P0/1 The corpus comprises 88 second Iron Age sites, all related to iron production activities, and divided into 7 categories
- P0/2 The sites present various degrees of erosion
- P0/3 The data from the listed sites are of varying qualities, and are classed in 3 categories
- P0/14 Evaluating the losses of metal enables the forge's production to be quantified
- P0/20 The waste taphonomy allows characterisation of how the deposits were made
- P1/4 Post-reduction activities were present on 84% of the sites
- P2/4 During the second Iron Age forging tended to be separated from reduction spatially
- P3/2 The post-reduction chaînes opératoires (forge activities) vary from site to site but are of relatively equal intensity on a regional scale
- P3/3 The inclusionary quality of the metal worked differs from site to site
- P0/9 In the second Iron Age the consumption of articles made of iron evolved form a restricted so-called "prestige" consumption to a generalised "utilitarian" consumption
- P0/15 Distinct technical procedures correspond to distinct skills
- P0/16 Until the industrial revolution the uses of post-reduction sites were domestic, artisanal, or proto-industrial
- P3/4 The workshops may be isolated or correspond to a concentration of activities in a single place, or again to an artisanal quarter grouping interdependent activities together
- P3/2 The post-reduction chaînes opératoires (forge activities) vary from site to site but are of relatively equal intensity on a regional scale
- P3/3 The inclusionary quality of the metal worked differs from site to site
- P0/10 The north of the Paris Basin has a multitude of communication routes (river and land)
- P0/19 EDS analysis of the slag inclusions in the metal allows its origins to be studied
- P3/1 During the second Iron Age, in the richest ore-bearing regions, raw iron production intensified just as global consumption of iron artefacts increased
- P3/2 The post-reduction chaînes opératoires (forge activities) vary from site to site but are of relatively equal intensity on a regional scale
- P4/1 During the second Iron Age an ever increasing division of the chaîne opératoire is apparent
- P4/3 During the second Iron Age commercial networks met the raw material needs of the regions that did not produce raw iron
- P5/1 During the second Iron Age iron-producing activities are found to have broadened in their scope: being purely artisanal in Block I, with domestic activities and artisanal quarters emerging in Block II, and proto-industrial productions in Block III
- P5/2 During the second Iron Age artisanal and proto-industrial forge activities were located in high hierarchic rank sites
- P4/1 During the second Iron Age an ever increasing division of the chaîne opératoire is apparent
- P4/3 During the second Iron Age commercial networks met the raw material needs of the regions that did not produce raw iron
- P5/1 During the second Iron Age iron-producing activities are found to have broadened in their scope: being purely artisanal in Block I, with domestic activities and artisanal quarters emerging in Block II, and proto-industrial productions in Block III
- P5/2 During the second Iron Age artisanal and proto-industrial forge activities were located in high hierarchic rank sites
- P4/1 During the second Iron Age an ever increasing division of the chaîne opératoire is apparent
- P4/3 During the second Iron Age commercial networks met the raw material needs of the regions that did not produce raw iron
- P5/1 During the second Iron Age iron-producing activities are found to have broadened in their scope: being purely artisanal in Block I, with domestic activities and artisanal quarters emerging in Block II, and proto-industrial productions in Block III
- P5/2 During the second Iron Age artisanal and proto-industrial forge activities were located in high hierarchic rank sites
- P6/1 In Block I production is weak and homogenous and destined for elites who assure direct or indirect control
- P6/2 Block II was a phase of transition; the manufactured products spread more widely through society and the elites transformed the way they dominated the production
- P6/3 During Block III a phenomenon of regional specialisation emerged and the iron economy (production/commerce) was dominated by the agglomerations and aristocratic farms
FROM PRESTIGE TO PROTO-INDUSTRY: IRON PRODUCTION EVOLUTION DURING THE SECOND IRON AGE IN THE NORTH OF THE PARIS BASIN
Keywords
Paris Basiniron metallurgyiron ore reductionpost-reductionforge activitiesIron AgeLa Tènearchaeometric researchcraft organisationINTRODUCTION
The advent of iron in northern Europe, and more particularly in the north of France, is a fundamental fact for understanding the economic and social changes that occurred during the Ages of metals. Iron is particularly effective when used to make artisanal or agricultural tools and weapons. As is often the case for new “arrivals”, at first it was only used as prestige goods for the elite. Accordingly, this new introduction was no great revolution in itself—its widespread use was what would start upheavals. This generalisation did not involve the articles’ manufacture on the spot and still less primary iron production (ore reduction). So, controlling this commodity’s production and/or circulation seems to have been an important issue. This is one of the main arguments proposed to characterise the emergence of certain forms of centralising power from the end of the Hallstatt to the end of La Tène; but up to now no research study has really shown the relations between power, production and social changes.
The north of the Paris Basin has its place in this general reflection on the role played by iron in the growing complexity of societies, at the margin of the important political centres of the first Iron Age. Before the 6th century this region was pushed out to the second circle of the Mediterranean “world-economy” in which the “Celtic Principalities” seem to have been intermediate entities dominating the transactions (Brun 1993). Not until the 5th century—early La Tène—did Champagne take the place, to a lesser degree, of the north-west of the Alps and a more complex form of social hierarchisation emerges in the region. During middle and final La Tène the objects in iron would be democratised to the point of becoming omnipresent not long before the Roman conquest. In this period a more complex form of social organisation also emerged, materialised by agglomerations in which artisanal activities were concentrated—the first phenomena of social mutation, harbingers of the great upheaval to come—the emergence of the State. In La Tène D these concentrations of population would give birth to the oppida (Brun 1995; Brun et al. 2000). During this major increase in complexity iron is assigned the role of moving force. It seems to have allowed agricultural surpluses and enabled “urban” communities to concentrate for other forms of production.
The geographic zone considered is confined between the Meuse and the Channel coast and between the Seine and the Somme. It can be encapsulated by the term northern Paris Basin.
As far as iron-producing potential is concerned it is characterised by a very strong contrast. Certain zones, known for their precocious exploitation of iron, adjoin others characterised by an apparent absence of smelting sites (absence of ore deposits?), that does not, however, imply the absence of iron-working. Materials and knowledge circulated; the activities of the forge could easily escape the constraints of geology thanks to the circulation of semi-products—iron ingots. A previous work (Bauvais 2001), comparing the final La Tène in Bohemia, southern England and northern France, seems to show the latter region was organised in a singular way, with forge activities concentrated at sites having a high hierarchical rank. The cause suggested was the unequal distribution of ore deposits involving regions producing more raw iron and regions where only transforming activities were present. In this context the acquisition of semi-products did not seem to be uniform. In certain sectors production was local and distributed in the vicinity. In others, obtaining the raw material depended on medium or long distance supplies from the producing regions; domination of the main commercial centres and circuits was the prize for controlling this commerce. (The high price of this commerce led to the domination of the main commercial centres and circuits by the elites.)
Our research concerned a corpus of 88 sites connected to iron producing activities, through the presence either of production activities or of raw material deposits.
To deal with this corpus we have mainly used a technological research methodology, resulting from archaeological and archaeometric approaches, so as to define the main lines of the chaînes opératoires (Fluzin 2002; Bauvais, Fluzin to be published b). In this chronological and geographical context we have tried to reconstruct the way the organisation of iron production activities evolved in their multiples forms—reducing, refining, manufacture, and maintenance—as society became more complex during this period. As iron production and its regional organisation formed a complex system, we also studied it from other angles, both social (economic, social and symbolical) and environmental (potential resources) (Butzer 1982; Bauvais, Fluzin to be published b). We tried to see how the interactions between social elites and productive activity could evolve and what that implied for the organisation of networks for acquiring/redistributing iron (raw material and manufactured products) in a contrasting geographic space.
Our results show, within the limits of available data, that at first during Hallstatt D3/La Tène B2 (500-250 BC) all the sectors were organised in the same way. Where the production sites are known they were situated outside or close to the homes of the smiths who sporadically produced their own raw material (Dunikowski et al. 2007) so as to supply the social elites with prestige goods. Other sites are the momentary forges of smiths supplying their skills to order. Production seems to have stayed on a local level while making substantial use of imports.
During La Tène C1/La Tène D1a (250-125 BC), the smelting sites supplied an increasing number of forge sites spatially distinct from the primary raw material production—specialisation (Bauvais, Fluzin to be published a). The forge sites were nevertheless the residences of an elite with a new status based on artisanal products. The finality of these products now extended beyond simple elite demand and they were distributed at least locally, if not regionally. Domestic maintenance activities seem to have come on the scene at the same time as the wider use of agricultural tools made of iron; imports of raw material seem to have contributed significantly to the rising demand.
Finally, during La Tène D1b/D2b (125-30 BC) there was a separation between the south-east of the zone studied (rich in ore) and the rest of the sectors (regional specialisation). Smelting was much more intense there and specialised sites produced a quantity of metal going well beyond local needs. In parallel, certain sites (open agglomeration) transformed this raw material for medium or long distance exportation (proto-industry). For the remaining sectors, primary production (reduction) was low. In the north-east refining has only been found in the oppida which seem to have had a monopoly of this activity. As consumption was visibly more important than local production, long distance trade seems to have had still more importance than in previous phases.
Thus—in terms of relations between the elites, production, and exchange networks—until La Tène B2 production seems to have been for a ruling class. However, the craftsmen were not necessarily subject to this domination owing to their small numbers and expertise, which may well have given them a privileged status. The subsequent tendency towards broader iron consumption in La Tène C1 is evidence of the elites’ loss of power, but the formation of the open agglomerations and the appearance of “producing farms” show the elite was heavily involved in its production. At the end of finale La Tène the advent of the oppida is associated with a cornering of raw iron production (as certain open agglomerations). The oppida seem to have played an important centralising and redistributive role over and above their productive function. On the level of their direct influence they drained the basic resources and on a larger scale they encouraged trade and the importing of prestige goods.
This work is the logicist rewriting of a part of the doctoral Thesis of Sylvain Bauvais “Evolution de l’organisation des activités de forge dans le nord du Bassin parisien au second Age du fer. Etudes pluridisciplinaires de la chaîne opératoire en métallurgie du fer” (Evolution of the organisation of forge activities in the north of the Paris Basin in the second Iron Age. Multidisciplinary studies into the chaîne opératoire of iron metallurgy), given at the University of Technology of Belfort-Montbéliard in September 2007 under the direction of Philippe Fluzin.
ARCHAEOLOGICAL DATA
Site Corpus
P0/1 The corpus comprises 88 second Iron Age sites, all related to iron production activities, and divided into 7 categories
This study concerns 88 sites spread over a geographic zone confined from east to west between the Meuse and Normandy, and between the Seine to the south and the Somme to the north. The study deals with a period going from Hallstatt D (beginning of local production) to the Roman conquest (change in scale of production).
Location of the sites concerned by the study
Distribution of the sites according to category
[+]Open rural settlements
8 sites out of 88 in the corpus. These sites are the most problematic to interpret due to their open space and the consequent difficulty of relating a certain quantity of slag to a surface-area. The majority date from final Hallstatt /early La Tène, even from the beginning of middle La Tène; these sites are mainly agricultural.
[+]Closed rural settlements
The majority of the sites studied with 41 occurrences. They are also the most common sites from the middle La Tène. They are mainly agricultural even if they can be centres for artisanal activities just as for cultural - or ostentatious (banquets…) - activities.
[+]The workshop sites
The workshop sites represent 10 sites out of 88 in the corpus. These are production sites cut off from domestic space. They are only reduction sites; no forge workshop has been found outside a settlement.
[+]Open agglomerations
The open agglomerations number 9 out of the 88 sites in the corpus. These sites bring together many more individuals than the usual rural sites. These "townships" are systematically the centre for craft and commercial activities (local and long distance exchanges), even if their organisation seems closer to a juxtaposition of units near rural settlements. These agglomerations emerged during La Tène C1.
[+]The oppida
They number 5 out of the 88 sites studied. They are real towns encircled with fortifications and with all the attributes of a decision making centre centralising regional resources. The oppida emerged during La Tène D1b, either developing from an open agglomeration, or ex nihilo on a new location.
[+]The sanctuaries
They represent 8 sites out of the 88 taken into consideration. They are not, strictly speaking, production sites, but they yield a large quantity of "sacrificed" metallic objects, including semi-products and smith's tools.
[+]Indeterminate sites
The indeterminate sites represent 7 out of the 88 studied.
P0/2 The sites present various degrees of erosion
The degree of erosion is represented by an index going from 1 to 5. Index 1 corresponds to very weakly eroded sites with at least a part of the ground level preserved. As for level 5 it indicates very strong erosion, while 3 corresponds to "classic" erosion of a site by farming after its abandon.
Table of indices of erosion of the sites taken into consideration in the study
P0/3 The data from the listed sites are of varying qualities, and are classed in 3 categories
Depending on their origin the data's relevance cannot be placed on the same level when analysed. Thus, three types of data are accessible: bibliographical data from research by non-specialists, research by specialists, research on finds effected by ourselves.
Classification of the sites according to the quality of information available
[+]Sites known through bibliography
This concerns 34 sites out of 88 in the corpus. They are sites of which the finds came neither into our hands, nor into those of another specialist in iron metallurgy. The data only consists of summary remarks or counts by non-specialist archaeologists needing, in most cases, reinterpretation (especially in the descriptive vocabulary).
Lists of the bibliographical sites
[+]Sites known through bibliography but studied by specialists
This concerns 19 sites out of 88 in the corpus. These sites are connected to specific regions: at the confluence Seine/Yonne, in the Sénonais, in the Othe Country, or the Evreux region, corresponding to the research of Christophe Dunikowski and Sandra Cabboi. The data published can be considered to be sure and are exploited directly.
List of the bibliographical sites studied by specialists
[+]Sites of which the finds have been restudied
This concerns 35 sites out of 88 in the corpus. Finds from these sites have been analysed quantitatively and qualitatively. The data from these analyses furnish the most reliable information, most apt to address the issues raised by this study. Among these sites, 21 received a more profound study with archaeometric techniques (metallography and chemical analysis).
Lists of the sites analysed for this study
Description of the data
P0/4 The slags, making up the greater part of iron-production waste, are classed into 7 categories depending on how they were formed
Slag is produced at each phase of the chaîne opératoire, from reduction in the bottom of the furnace to making or repairing articles in the forge. It is the most frequently found waste, as it cannot be recycled.
[+]Furnace bottom slag
This slag is produced during reduction in a slag-pit furnace (Pleiner 2000): this is the part of the waste left to solidify inside the pit under the shaft. It takes the form of a mass of slag marked by numerous impressions left by charcoal and the receptacle in which it was formed. Depending on its size and density - presence of porosity more or less important - this slag can be as heavy as 90 kg (Cabboi et al. 2007).
List of the sites with bottom slag
The bottom slag
[+]Internal slag
This waste is formed during the reduction process in the lower part of the shaft. These droplets and filaments solidified during the slag's cooling when liquid between the charcoal fragments at the base of the structure - giving them this form of drops or irregular filaments.
List of sites with internal slag
Internal slag
[+]Flowed-out slag
This slag is formed flowing out from the reduction furnace (furnace with out-flowing slag). It can take the shape of blocks, superposed run-offs, or slabs. Their morphology and texture depend essentially on the slag's viscosity (chemical composition and temperature). The slag takes the form of the floor it flows over.
Flowed-out slag flows
[+]Slag cakes
A cake is a circular or oval piece of slag with a plano-convex section formed when air reaches the hottest point of the forge hearth. Its bottom surface moulds the bottom of the hearth. The upper surface can be concave, flat, and even convex. Cakes result from forge working between hearth clearing operations, which occur when the smith is interrupted in his work. Accordingly, these cakes contain all the elements introduced between the two clearings
Slag cakes
[+]Formless slag
These are small globules of slag (1 to 3 cm3) formed on the edge of the cake but not adhering to it. Their separation is due either to the small amount of loss during working - if the activity is not very intense - or because they were too far from the cake while it was forming. The simple act of plunging the object being worked or a rabble (iron bar used in metallurgy) in the hearth can separate these fragments from the spongy slag mass. Their small size, fragmentary form, as well as the peripheral and sporadic conditions behind their formation make them less than wholly relevant for analysing the chaîne opératoire. All the same, their proportions can provide important indications on the working's intensity.
Formless slag and the sidewalls
[+]Magnetic slag
Magnetic slag is very similar in appearance to formless slag. They are little pieces of slag that react strongly to a magnet. They are composed of metallic fragments lost in the hearth during working. They can be result from forging an object but more often from refining (gromps). Without metallographic analysis distinguishing these various origins is impossible.
[+]The slag-coated walls
These come from the zone around the air intake. They are very siliceous vitrified fragments of wall formed around the air intake. These fragments have a slag-coated vitrified face and a highly rubefied face on the torn off side. Sometimes they retain the impression of the ventilation orifice. They were thrown away when the wall was remade as the latter degraded rapidly and needed regular maintenance. Either the air intake orifice clogged up with slag, or the wall fragmented or was torn off on removing a cake stuck to it.
P0/5 For the second Iron Age archaeological structures enable the iron production activities carried on in the workshops to be identified
The workshops can concentrate all or a part of the phases of the iron-production chaîne opératoire. Nonetheless, the archaeological structures belonging to each of these phases can be distinguished. A reduction workshop comprises one or more furnaces, a zone for storing charcoal and ore, pits for extracting the clay needed to build the furnace, and a refuse zone for the slag (ferrier). A second Iron Age smithy comprises one or more hearths on the ground connected to their bellows, one or more anvils, possibly recipients - water, antioxidant additives, other mixtures - and a zone for stowing tools close to the work zone. These elements can be concentrated in a space of 15 to 20 m². The smithy floor is covered with iron-working waste (shreds, fragments of slag). The anvil is never more than 1.5 metres from forge hearth - owing to thermo-mechanical requirements (Mangin et al. 2000b). In general this space is covered to protect the work from the weather - the darkness helping the smith to estimate the heated metal's temperature. However, the anthropological and archaeological examples confirm a simple awning may suffice, and even an open-air forge is envisageable for a short time or a particular piece of work.
Table summarising structures connected to iron production
[+]The buildings
Out of 88 sites in the corpus, 7 buildings dedicated to forges have been found. They are buildings on posts of 16 to 60 m². The plans are very varied and the fittings can be very simple (Villiers-sur-Seine). There is no common organisation, besides the recurrent presence of awnings (Condé-sur-Suippe, Ronchères, Vernon, Rue, and Bayonvilliers). Apart from its practical function, the space could be used for buying and selling in a commercial environment, as at Bibracte, Vernon or Condé-sur-Suippe. Some have similarities with known workshops, such as the forge of Ronchères and that of Paule "Le Camp de Saint-Symphorien" (Menez et al. 2007) marked by symmetry between two pits with identical plans. Another point in common is noticeable between the sites of Bazoches-sur-Vesle, Ronchères, Paule, and Bibracte (Pernot et al. 1993; Pernot et al. 2002) which have a channel running across a part of the smithy's floor level. Two other complexes, very similar in morphology and organisation, can be seen at Lacroix-Saint-Ouen "Le Pré des Iles" and at Bazoches-les-Bray "Près le Tureau aux Chèvres".
The forge buildings
[+]The low slag-pit furnaces
This type is a furnace comprising a pit on which a shaft (chimney) is erected. Several variations are known, depending on the presence or absence of a door giving access to the reduced metal (multiple use or not). During reduction the metal concentrates in the hottest point of the furnace, under the ventilation intakes. The liquid slag resulting from the fusion of a part of the ore's iron oxides, other substances contained in the ore as well as the material from the charcoal ash, the clay wall and possibly additives, is in part separated vertically from the metal and stocked in the pit underneath. These furnaces are characterised by the production of furnace bottom slag.
The slag-pit furnaces
[+]The low slag-tap furnaces
These are reduction furnaces in which the metal and slag are separated horizontally. Orifices are made in front of an evacuation ditch to let the slag out during the reduction. This enables more slag to be evacuated and so a denser mass of metal with more volume to be produced. Numerous variants are known but in most cases these furnaces are multiple-use. They are characterised by outward flowing slag.
[+]The polyvalent forge hearths
These hearths are large enough in size to allow the working of both long voluminous and smaller pieces. The hearth of Ronchères is more or less square in plan 2 by 1.5 metres with two rubefied zones indicating repairs or an adaptation of the heating area depending on the work. The hearths of Condé-sur-Suippe are very similar in the main. That of workshop I1 is sub-rectangular in shape and of a particularly imposing size (280/140/35 cm). The hearth of workshop I2 is an irregular oval and its size is also considerable (220/140/60 cm). That of workshop O1 is sub-rectangular but particularly low (120/90/5 cm). At Allemant, the circular or sub-circular hearths about a metre in diameter may also be considered as polyvalent forge hearths. Lastly, one of the hearths of the Villiers-sur-Seine workshop may be likened to this type (130/80/10 cm).
The polyvalent forge hearths
[+]The specialised forge hearths
These are hearths with morphology implying a more specialised function. At Vernon 2 small circular hearths have been preserved (dia: 30-40 cm; depth 15 cm). Such heaths could not have allowed pieces larger than 25/30 cm to be forged, for they could not have heated them as a whole. The second hearth of Villiers-sur-Seine has an identical circular plan and indicates a change in the workshop's purpose, towards smaller pieces. At Condé-sur-Suippe a hearth has a very particular horseshoe floor plan resembling a modern cartwright's workshop. Lastly, cementation hearths are known for more recent periods. These activities are attested at Bobigny "Stade de la Motte" through the presence of cement, but no specialised structure has been found.
[+]The special forge hearths
These are large quadrangular pits, of up to 3 by 2 metres, with vertical sides and very variable rubefaction both in intensity and location. Certain zones have greater rubefaction such as the positions for air intakes. Often, the rubefaction can only be seen in one half of the structure, making the other a kind of kiln firebox. The presence at Tergnier "Les Hauts Riez" of 6 of these structures together with forge and reduction slag implies they were used as refining hearths like those found at Paule (Berranger 2006, excavation report - 2005 campaign). At Allemand "La Vallée Guerbette", all the phases of the chaîne opératoire - from ore extraction to forging - can be made out and 8 structures of this type are present. Lastly, this type of structure has also been found in Moselle at Rémilly "Petite Fin" (Leroy 1997). Up till now their interpretation as refining hearths has been based on their context and imposing size that made it possible to keep the bloom to be refined in a reducing atmosphere.
[+]The systems of ventilation
For the period the ventilation of the forges was lateral and the system for pumping the air was made of perishable material. A conduit called a tuyere was used to isolate the ventilation system thermally. It could take the form of a simple inlet made in the floor perforating the wall or again of a detachable baked clay tuyere block directly placed in contact with the flames. The tuyere blocks seem to have emerged later than the floor inlets. In the region studied the only signs of their use date from La Tène D2: a single orifice tuyere block has been discovered at Condé-sur-Suippe, and several indications imply they were used in the oppidum of Villeneuve-Saint-Germain. These two varieties of tuyere could include 1 to 3 perforations so as to widen or reduce the heating surface.
The ventilation systems
P0/6 The forge tools can be divided into two large families
The tools are personal objects reflecting the work of the individual who used them. They were continually modified and adapted to the work of the smith, to the idea he had of their use and to what he produced. The small quantities of discoveries only allow a qualitative study of the tools. In the context of the second Iron Age this means their presence is linked to specialised activity.
Summary of tools linked to iron working
[+]The active tools
These were directly wielded by the smith at work. They were for various shaping processes. They were for hammering, deforming, cutting, piercing, abrading… Consequently, their types and morphologies were very important. These tools were adapted to each speciality and each smith, but could also be modified in use if necessary. They were tools of direct (hammers) or indirect percussion (setts, chisels, dies…), for gripping (pliers, tongs), shovels or for abrasion (files, sharpeners, polishers).
The hammers
Indirect percussion tools
The tongs
The files
The shovels
[+]The passive tools
The anvil is the passive tool par excellence. Several types of anvils are known, depending on the material they are made of (iron, wood, stone), and their form. They can be compact blocks more or less large in volume, of variable shape, or have a simple beak. For stone anvils in general the material's resistance only allowed large and compact volumes. Quenching-troughs are also part of this category. They contain liquid in which the smith plunges his metal to effect a thermal treatment called quenching.
The anvils
P0/7 The metallic elements can be separated into 6 categories
The metallic waste produced by a forge and its morphology contribute invaluable information on the metal worked (long, flat, massive product) and the type of objects produced as they represent intermediate states of the material from the semi-product up to the manufactured article.
Summary of metallic waste
[+]Formless waste
This category brings together compacting metal fragments and eventual flakes.
[+]Flat product offcuts
This category brings together sheet or plate offcuts.
[+]Long product offcuts
This category brings together separate offcuts depending on their thickness between rod and bar.
[+]Unfinished pieces
This category brings together unfinished articles and failures.
[+]Half-finished products
A semi-product concretises an intermediate state of the material between the raw metal out of the reduction furnace and the finished article. The semi-products' sizes and shapes vary depending on the iron's crude initial mass, the amount of refining work done, the metal's nature (iron/steel) and the product's end-use. These variations are expressed by graded commercial values. So the metal was traded and circulated under multiple forms.
The semi-products
[+]Recuperated metal
This category concerns objects and fragments of objects used for recuperation.
REFERENCE DATA
Societal data
P0/8 The second Iron Age was a theatre for a constant increase in social and economic complexity
The period concerned witnesses the collapse during early La Tène of the magnificent "Celtic Principalities" and a return to an organisation that may be described again as chiefdoms (Brun 1993). In La Tène C minted coinage was adopted and the first agglomerations developed. Subsequently, during La Tène D what can be unambiguously called a state system emerged, centred on towns - the oppida (Brun 1995; Brun et al. 2000). This underlying complexity was accelerated by the stimulating influence of neighbouring cultures through trade and other intercultural contacts.
Chronological table showing the main socio-economic developments
[+]Early La Tène
The beginning of the second Iron Age was characterised by a stratified family and clan type society with small sized controlled spaces (Brun 1995; Baray 2003 p. 389). The elite's power, though they monopolised much of local wealth and above all that from long distance trade, remained restricted. On the other hand, at the end of La Tène A the necropoles showed a connection, at least ideal, between military attributes and the social elite. The most common settlements are open and inside this category various hierarchical levels may be seen (Gransar et al. 1999).
[+]Middle La Tène
The beginning of middle La Tène is connected to the Celtic migration described in the ancient texts resulting in the north of France by a drop in the number of inhabited sites. Data are reduced for this phase, but it seems society became more egalitarian (Demoule 1993). Throughout the 5th - 4th centuries forms of settlement barely changed. They were open not very structured installations of 1 to 2 hectares. Few enclosed sites have been found, but they reveal quite superior wealth. A subsequent return to a landed aristocracy seems to have occurred. Together with growth in population the farms become more numerous, they are enclosed and mark their territories more. This period also witnessed greater social hierarchisation and the emergence of open agglomerations several hectares large. These "boroughs" were centres for artisanal and commercial activities and evidence that farming enabled a section of the population to live apart from the rural world. At the same time coin use and production developed, just as religious sanctuaries were established.
[+]Final La Tène
In final La Tène the agglomeration phenomenon intensified and real towns were established ex nihilo on new sites: the oppida. They were accompanied by the generalisation of minting and the first signs of a state political system. The oppida included true artisanal quarters, streets, and squares - all according to a predefined plan encircled by a fortification. They also had all the attributes of a decision-making centre with the minting of coins and the centralisation of regional agricultural and commercial resources. This development was accompanied by an increase in the number of individuals inside the elite. Most of the latter remained a landed class, and its possible relations with the urban sites are still difficult to envisage. In any case, the military troubles caused by the Roman invasion restored to the warrior aristocracy its noble status.
P0/9 In the second Iron Age the consumption of articles made of iron evolved form a restricted so-called "prestige" consumption to a generalised "utilitarian" consumption
From the transition between final Hallstatt and early La Tène, some agricultural tools were commonly used and the daily tools were restricted to knives and axes. Iron was essentially used as "prestige goods" for jewellery and weapons. The needs of a simple agricultural farm consumed but little iron. Only the residences of the elite could consume substantial quantities of iron artefacts - more for reasons of "fashion" than wear. From La Tène C1 the agricultural tools seem to have been used more and more - particularly iron ploughshares from La Tène C2. Iron objects such as fibulas replaced their equivalents in copper alloy but their presence remained restricted to a part of the population. In La Tène D1b the use of iron became common; many articles began to be made in iron, and the use of iron in construction became standard.
Representation of the evolution of iron consumption in the second Iron Age
Environmental data
P0/10 The north of the Paris Basin has a multitude of communication routes (river and land)
The form of the landscape and the hydrographic network of the north of the Paris Basin offered a multitude of major natural communication routes, oriented mainly from east to west and materialised by the important rivers - Seine, Marne, Yonne, Oise, Aisne, and Somme. Other smaller watercourses completed this relatively dense network. The terrestrial routes are more difficult to bring to light. However, the Gallo-Roman roads that followed the Gallic routes give an idea of what existed during final La Tène. These terrestrial routes completed the navigable waterways by forming a north-south network.
The communication routes
P0/11 The region studied can be divided into 3 zones: a North-West zone, a North-East zone, and a South zone
Certain zones, known for their primary iron production, adjoin others characterised by an apparent absence of reduction sites, - both before and after the Roman conquest.
The principal historic zones of deposits of iron ore in the North of France
The geographic zones defined in this study
[+]The North-West
This geographical entity could be circumscribed to the west of Picardy - the half west of the Oise and the Somme - and the northern half of Normandy, the Seine more or less acting as southern frontier. It includes 23 sites in the list. This geographical unit is endowed with important ore deposits but few reduction sites are known for the Iron Age. It seems to have long stood back from the long distance trade networks, even if the Seine and the Somme could be important commercial highways.
[+]The North-East
In large measure this zone can be delimited to the eastern half of Picardy and the western fringe of the Champagne-Ardenne region. It includes 31 sites in the list. It is endowed with small less than abundant geological resources as the low number of reduction sites known at all periods shows. On the other hand it had a flourishing trade network.
[+]The South
This zone may be defined as the slightly larger space of what today is the Ile-de-France. It includes 32 sites in the list. This geographical unit is endowed with very important ore deposits and is the most densely exploited iron producing zone. It is positioned along the major communication route of the Seine.
Anthropological and experimental data
P0/12 Following the anthropological and experimental examples the chaîne opératoire in direct iron production may be divided into three major phases: reduction, refining, and object manufacture
Refining and object manufacture are post-reduction or again forge activities: refining forge and manufacture forge. Separating these last two phases can prove delicate, as they can take place without interruptions.
Synthetic table of the iron production chaîne opératoire
[+]Reduction
This first stage consisted in transforming the iron ore into a bloom in a low furnace. This operation combining ore, charcoal and oxygen occurs at temperatures below the metal's melting point. Iron and steel agglomerated in a spongy state while the slag produced was liquid. This resulted in an iron and/or steel bloom more or less compact with more or less slag and charcoal depending on the technique employed.
Schematic representation of an iron ore reduction oven
[+]Refining
Refining consisted in hammering the raw metal into a more compact mass by agglomerating the separate metal fragments, welding the initial porosities onto one another, and driving out the maximum of slag. The techniques used depended on the initial texture of the bloom and the products desired. Next, a series of forge-weldings (kneading) allowed the homogenisation of a mass of heterogeneous consistency by transforming more or less steely zones into a succession of layers. This toughened the metal giving it better mechanical properties (pseudo-damascene or pattern-welded damascene). The metal was refined throughout the hammering, from the bloom to the finished article, but the process could still be interrupted and the resulting product is called a semi-product.
Essay at typology of refining processes
[+]Object manufacture
The metal worked might be a semi-product, the first stage of the article to be produced, or a mass created from agglomerating various metal fragments (recycled for example) to which the smith, thanks to a large range of skills and technical procedures, applied physical and chemical transformations. His choices would depend on the raw material - quality, composition - his skills, and the technical complexity of the artefact desired.
Synthetic table of forge procedures
P0/13 An evaluation of the yields is possible from reduction waste
Evaluating the yield of a furnace or a reduction forge is possible thanks to a material balance (chemical balance). All the substances introduced into the furnace must come out. Thus, chemical analysis of the ore and slag on the one hand and a quantitative (weight) evaluation of the slag on the other, enable, by deduction, the quantity of metal produced to be known (Serneels in Mangin dir. 2004 p.130).
Schematic representation of material balance
P0/14 Evaluating the losses of metal enables the forge's production to be quantified
During post-reduction activity a certain quantity of iron is lost, either as metal or oxide. In order to estimate the quantity of iron worked on a site the quantity of iron lost during the formation of waste slag and scale has to be known. Several experimental studies give an idea of the metal lost during the different phases of work in a forge (Serneels in Anderson et al. 2003).
Synthetic table of metal lost during forge work - experimental evidence
P0/15 Distinct technical procedures correspond to distinct skills
Each technique did not require the same apprenticeship, nor the same expertise, nor the same skill. These techniques can be classed in 4 degrees: - simple procedures for work on a single piece of metal; - work on highly carburised steel or a highly heterogeneous mass and simple welding techniques on low carbon steel; - so-called advanced techniques: thermo-chemical processes - cementation and carbonitriding - and iron/steel welding; - techniques for experts (Pleiner 2006): more a complicated succession of processes as for forging laminated damascene swords.
Summary table of skills necessary for iron working
P0/16 Until the industrial revolution the uses of post-reduction sites were domestic, artisanal, or proto-industrial
If the ironware produced is considered to be for: - the strict needs of a limited community without commercial implications: the production was domestic; - at least partly, commercial distribution: the activity can then be described as artisanal. Within the field of artisanal activities a nuance may separate the artisanal from the proto-industrial. This distinction is made following a definition proposed by the geographer A.J.-M. Bernard: "Industry may be distinguished from craft production by its standardised products in series (no longer one off, or nearly so) its exteriorisation, codification, and standardisation of secrets of manufacture, its division of labour as opposed to craft versatility, and use of machinery instead of manual work, with the enterprise's capitalistic and geographic concentration instead of the workshop. There subsists from this distinction the criterion of enterprise size, used to separate statistically and legally crafts from industry." (Bernard in Levy, Lussault dir. 2003). The only term it seems necessary to exclude from this definition, so as to apply it to Iron Age cultures, is machinery.
Methods of scientific analysis and reference data
P0/17 Micrographic analysis of slag enables the chaînes opératoires be characterised
This method makes use of the theoretical and practical rules of thermodynamics. From a polished section it makes it possible to identify the constitutive phases' nature - chemical and mineralogical - and morphology - crystalline or amorphous - of which the texture illustrates the conditions they were formed in. It supplies information on the elements used and partly lost in the hearth during working (loss in metal - fragments, beads or filaments - slag, oxides, sand, scale, clay, charcoal, ash, additives, etc.) and how the processes took place - relation oxidation/reduction, temperatures and duration of heating. The slag cakes are the first forge slag to be analysed, for they contain all the elements lost in a forge hearth between two clearance operations. All the data previously cited were then stratified inside the cakes and form a coherent succession of technical sequences allowing the chaîne opératoire to be broadly reconstructed.
Evidence of refining
Evidence of oxidation
Evidence of temperature: burnt metal
Evidence of temperature: fayalite
Evidence of temperature: wustite
Additives: hercynite
Thermo-mecanics: hammering
Thermo-mecanics: welding
[+]Research methodology
Micrographic analyses of slag proceeds as follows:- take macrographic photos of all faces of selected samples- slicing with lubricant- photograph of cut surface. These photos make examination of the sample easier (heterogeneity, stratification, porosity, distribution of different constituents…); - coating with suitable thermo-hardening resin;- mechanical polishing with lubricant up to granulometry of 1 micron;- photograph and scan of polished surface;- complete inspection under metallographic microscope and taking of micrographies;- chemical treatment with Nital if metallic elements present;- further complete inspection with micrography of the characteristic structures;- drawing of cut surface based on analysis observations - macros and micros - and transfer of references to the negatives.
[+]Distinguishing refining from object manufacture
The most delicate distinction to show owing to the possible continuity between refining and object manufacture in a forge slag-cake. Nevertheless, the convergence of several pieces of evidence may make it possible to show the presence of refining and sometimes characterise the initial compacting of the metal worked.
[+]The degree of oxidation
The oxidising atmosphere of the forge hearth eventually forms around the piece subjected to high temperatures a layer of oxide, called calamine. It is the origin of scaling. In the cakes they either come from the thermal shock during the heating or become partially detached due to a mechanical shock and come away completely during the subsequent heating. They can also form in the hearth through the oxides' liquefaction, linked or not to siliceous additives (globular scales but also globules of wustite scattered in the matrix). Wustite (FeO), the most commonly formed oxide, liquefies between 1,371 and 1,424°C. Using a siliceous additive lowers this liquefaction temperature. Thus, the proportion of metal lost in the form of oxides in the cakes is a good indicator of the more or less oxidising atmosphere of the hearth while in use.
[+]The additives
The purpose of the additives was to diminish the superficial oxidation by isolating the metal from the oxygen, but also to stop the metal from decarburising. The could take several forms such as a slip that covered the piece or simple sprays of sand. Welding also needed additives in order to eliminate the surface oxides and bring together two "clean" metallic surfaces. The silica grains aimed to break this layer open so as to bring the metals into contact. Pure silica fulfils this function best. On the other hand, this additive tends to stay trapped in the weld lines, which is why a combination with a flux - calcium or potassium - let the sand and oxides liquefy into a silicate easy to expel on hammering. These losses of oxide and these additives are the two main ingredients of fayalite (silicate of iron - Fe2SiO4) from the forge slag cakes. Their proportions and degrees of liquefaction would tend to form either fayalitic or clay-sand slag.
[+]Working temperatures
Preserved in their structure the cakes contain evidence allowing the working temperature and the speed at which the hearth cooled to be estimated. The percentage of porosities can indicate whether the slag was liquid or doughy. The size of the fayalite laths and the more or less dendritic form adopted by the wustite also indicate not only the temperature reached but also the speed of cooling. Multiplication of these phases inside a cake may also be evidence of important thermal phasing, characterising the thermal activity during a work sequence. Often, the highest temperatures were linked to more serious metallic losses in the form of "burst" beads or strings of beads. These are stigmata of a burning metal, most often steel.
P0/18 Metallographic analysis of the metallic elements enables the chaînes opératoires to be characterised
Each technical forge process transforms the metal's structure and/or texture. Unlike other chaînes opératoires these activities tend partly to eliminate evidence from preceding work sequences. Consequently, to detect the traces that are still visible it is necessary to investigate the "subject matter". Metallographic analysis was developed by metallurgists to study metals and their alloys. It allows the examination of textures - aspect of metallic grains, of oxides and inclusions - and determination of phases (iron-carbon alloys) and their organisation - heterogeneity, degree of compactness, welding, thermo-mechanical deformation, thermal and thermo-chemical transformations.
The metallic phases
Thermo-chemical processes: cementation
Thermal processes: tempering
Thermo-mechanical processes: welding
Thermo-mechanical processes: forge welding
Thermo-mechanical processes: pattern-welding
The additives: the inclusion of grains of sand
[+]Research Methodology
The metallographic analyses take place as follows: - take macrographic photos of all faces of selected samples - slicing with lubricant - photograph of cut surface. These photos make examination of the sample easier (heterogeneity, distribution of micro-inclusions, eventual weld lines…); - coating with suitable thermo-hardening resin;- mechanical polishing with lubricant up to granulometry of 1 micron;- photograph and scan of polished surface;- complete inspection under metallographic microscope and taking of micrographies;- etching with Nital if metallic elements present;- photograph of the surface revealed. These negatives enable the phases (iron-carbon alloys) to be located macrographically;- further complete inspection with micrography of the characteristic structures;- evaluation of the microhardnesses if necessary.- drawing of cut surface based on analysis observations - macros and micros - and transfer of references to the negatives.
[+]The metallic phases (iron-carbon alloys)
Depending on carbon content the iron/carbon alloy's structure changes. Ferrite consists mainly of pure iron - 0.02 % carbon; is very flexible and quite malleable. Cementite is a chemical combination of iron and carbon (Fe3C) containing 6.67 % of carbon composing the most carburised cast-irons. As for perlite, it is an aggregate of ferrite and cementite containing 0.8 % carbon - eutectoid steel. Naturally, multitudes of intermediates exist between these two states. Increasing the carbon makes the alloy harder but less resistant to mechanic demands (fragility). With the increase in carbon content the alloy's melting point falls considerably from 1536°C for ferrite (0.02% Carbon) to about 1135°C for eutectic steel (4.3% carbon).
[+]The thermo-mechanical transformations
These are processes for shaping the metal, otherwise called forging. They are manual procedures for shaping the metal while hot. They consist in subjecting the metal to a succession of heatings and beatings on the anvil so as to deform it through hammering. Making a piece entails a cycle in 4 phases:- Initial heating- The temperature maintenance phase (thermal homogenisation)- The phase of anvil hammering and reheating- CoolingDuring each of these phases various procedures and processes, both mechanical and thermal - desired or suffered by the smith - which occasion modifications to the material. This could be a simple hammering, welding through refolding (refining/homogenisation), pattern-welding (recycling), drawing, upsetting, shoulder or beak working, welding, cutting, drilling, stamping. Each of these processes requires thermal conditions suitable for the object's morphology and composition and produces characteristic waste.
[+]The thermal transformations
They modify the metal's structure, but not the alloy's composition, by playing on the heating temperature, its maintenance and on the speed of cooling. Hardening is used to increase the hardness of the steel - perlitic or ferritoperlitic structure. The steel is heated to between 850 and 723°C then plunged in a liquid to cool it rapidly. This creates unbalanced structures depending on the speed of cooling; troostite forms with middling speed cooling, bainite with quite rapid cooling, and lastly martensite with very fast cooling. Tempering is a technique for attenuating hardening. Heated to between 180 and 723°C, maintained at this temperature long enough to homogenise, and then cooled very slowly the metal loses some of its brittleness but also some of its hardness. Annealing is used to give steel back its balanced structure; it consists in heating to over 850°C and cooling slowly.
[+]The thermo-chemical transformations
These procedures consist in modifying the alloy's composition by diffusing certain elements from the surface while hot. Cementation - case-hardening - is a complex process consisting in incorporating carbon into the metal in order to modify its mechanical properties - harder but more brittle. It is effected by heating an object to an elevated temperature and keeping it in contact with a material capable of liberating carbon - cement. The carbon's diffusion depends on the variety of cement, the process's duration, and the temperature. Accordingly, cementation of a bar of ferrite to make a steel of 0.6/0.7% of C at 500µm using coal and bone dust needs about 10 hours at 700°C or 3 hours at 1,000°C. Nitriding and carbonitriding are processes for hardening an iron or steel superficially by having it react at a relatively low temperature - 500/550°C for nitriding and 650/850°C for carbonitriding - with a nitrogenous material combined or not with carbon. The hardening obtained is definitely superior to that for a cemented steel hardened through quenching. Adding this element causes the formation of nitrides in the superficial layers.
P0/19 EDS analysis of the slag inclusions in the metal allows its origins to be studied
Once the ore had been reduced the bloom contained inclusions of slag that refining would try to force out. The slag's composition came from non-reduced elements from the ore and other factors essential to the processes - furnace walls, charcoal, additive…) (Dillmann 1998, Dillmann et al. 2005, Dillmann 2006). Recent work shows the ratios between "non-reduced compounds" of the inclusions resulting from reduction are preserved, and in particular the ratios % mass SiO2 / % mass Al2O3, % mass CaO / K2O and the ratio % mass MgO / % mass Al2O3. In this way, the composition of these inclusions is characteristic of the chaîne opératoire the smith used when reduction, and by extension of his production workshop (extraction site, ore preparation, reduction processes used).
Example of chemical analysis of slag inclusions in the metal
[+]Principles of EDS analysis
This semi-quantitative method enables the punctual composition spectrum of a selected zone of a sample. By means of a scanning electron microscope the zone is bombarded by a beam of electrons causing the emission on impact of X-rays characteristic of the elements composing the zone. The EDS detector that receives these X-rays creates pulses with peaks proportional to the X-ray photon's energy. With a discriminator it is possible to sort the pulses by peak, and in this way count the incident photons according to their energy.
[+]Research Methodology
The sample is swept; the inclusions and their origins are detected (weld lines, groups of inclusions separated by welding…). Between 30 and 50 measures give sufficient statistical value. Though the reduction slag is reasonably homogeneous chemically on a macrographic scale, on the scale of the inclusions trapped in the metal - a few µm - a heterogeneity may emerge, due to what may be described as "nugget effect" inherent in the inclusion's size being inferior to that of the ingredients of the matrix. Sorting is then necessary so as to eliminate the smallest inclusions, the ratios between elements of which may not be preserved. The results are applied to a double-entry matrix in order to show clearly whether the ratios between the elements are constant. The coefficient of regression R² of the orthogonals of regressions passing through the origin superior to 0.6 will be considered relevant enough to validate a correlation.
P0/20 The waste taphonomy allows characterisation of how the deposits were made
The degree of fragmentation of the iron-production waste and its refitting enables the various treatments they underwent before being buried to be determined. A deposit directly in the pit will not produce the same destructions as a deposit - also in a pit - made after staying for a long time on the dwelling floor. The degree of fragmentation corresponds to the ratio between the weight of the fragmented slag cakes and that of all the cakes. This calculation can be made globally for the site but also on the scale of a structure or of a deposit within a structure. The extent of fragmentation can be a good indicator of the "life" preceding the waste's burial. The presence or absence of certain elements such as furnace-wall fragments is also an important indicator given this type of find is very fragile.
Synthetic table of the various types of deposits
INTERPRETATIONS
Socio-cultural context
P1/1 The second Iron Age can be divided in 3 chronological blocks
The evolution of iron consumption and the socio-economic context allows the chronological sequence to be divided into 3 blocks:- the first (Block I) between Hallstatt D3 and La Tène B2 (500-250 BC);- the second (Block II) between La Tène C1 and La Tène D1a (250-120 BC)- and the third (Block III) between La Tène D1b and La Tène D2b (120-30 BC).
P2/1 The sites may, in their chronological context, be classed according to their hierarchical rank
The definition of a hierarchical rank is relative in each of the periods. It depends on the movable remains, the activities that took place (cult, banquet, regional storing of produce, minting of coins…) and the structuring of the settlement (fortification, area, monumental and ostentatious architecture…). If the work carried out on the valley of the Aisne (Gransar, et al. 1999) and in the middle valley of the Oise (Malrain, Pinard 2006) is taken as a reference, a classification of the sites according to their hierarchical rank in society is possible. For Block I the sites may be divided in three categories: the small or temporary settlements, the open settlements that were renewed on the spot or moved, and the enclosed settlements - residence of the elites. Block II may be divided in 4 categories: the small farms, the medium-sized farms, the aristocratic farms and the open agglomerations - the last two being the residences of the elites. Lastly for Block III the sites may be divided in 4: the small and medium-sized farms, the aristocratic farms, the rank 2 oppida and certain open agglomerations, and the rank 1 oppida and certain open agglomerations - the last two being the residences of the elites.
Presentation of the hierarchical ranks in Block I
Presentation of the hierarchical ranks in Block II
Presentation of the hierarchical ranks in Block III (part 1)
Presentation of the hierarchical ranks in Block III (2nd part)
Reduction activities
P1/2 Reduction activities are present on 17 % of the sites
Morphological analysis of the slag and the presence of artisanal structures has enabled the identification of 15 sites as presenting reduction activities, i.e. 17% of the corpus.
P2/2 A great disparity exists between reduction sites in raw iron production yields
In most cases no chemical analysis gives us the data necessary for a quantitative estimation of production. However, the quantity of reduction slag found on the sites, the number of low furnaces uncovered or reconstructed thanks to the slag and furnace type used has let us show substantial disparity in the intensity of reduction activity at each of the sites. This intensity ranges from a single smelt with one pit furnace, attested by the presence of oven bottom slag thrown out into a silo at the site of Ecuelles "Charmoy", to more than 9,000 tons of slag and batteries of ovens with outward-flowing slag at the workshop site of the Clérimois "La Fouetterie".
P3/1 During the second Iron Age, in the richest ore-bearing regions, raw iron production intensified just as global consumption of iron artefacts increased
During Block I iron object consumption was low and reduction sites were small. No difference is apparent over the whole zone. The furnaces are of trapped slag type and single use, often single or maybe in groups of 2 or 3, but with no proof of synchronicity. During Block II although consumption of iron articles increased, the reduction sites appear not to have evolved either in organisation or in intensity. Their number is even smaller. This last fact is to be attributed to insufficient research rather than to reality. In Block III iron consumption became very important and the sites in the regions richest in ore such as Yonne, the south of Seine-et-Marne and the Pays de Bray seem to have reached a superior scale of production. Now the furnaces were multi-use with outward flowing slag, organised in batteries with production reaching up to 4,000 tons of iron at Clérimois during 200 years. The rest of the zone studied is not very well documented but the presence of refining activities in the oppida of Aisne indicates reduction activity was close at hand but never more than small in scale.
Forge activities
P1/3 The whole chaîne opératoire was present on 9% of the sites
Morphological analysis of slag and presence of artisanal structures show that 8 sites had both reduction and post-reduction activities, i.e. 9% of the corpus.
P1/4 Post-reduction activities were present on 84% of the sites
Morphological analysis of slag and the presence of artisanal structures show that 66 sites had post-reduction activities, i.e. 84% of the corpus.
Table of forge sites (part 1)
Table of forge sites (2nd part)
P1/5 The post-reduction waste shows different degrees of standardisation
This standardisation is illustrated by the waste's morphology and composition. Morphological families have been defined for the slag based on the slag-cakes' morphology and composition (fayalite/clay-sand) of each site. The number of these families indicates the variability, and so the extent, of the waste's standardisation. As for the metal, the type of product worked - long, flat, massive - manufactured articles and semi-products - is what has been studied.
Summary table of slag-cake families from the sites analysed
P2/3 The main post-reduction chaînes opératoires can be characterised
Four criteria are taken into account: - The complexity of the sequences of processes materialised by the cakes' typology; - Prominence the analyses give the processes; - The type of metal worked (morphology, inclusionary properties); - The type of production.
Synthetic table of the complexity of the process sequences practised on the sites analysed
P3/2 The post-reduction chaînes opératoires (forge activities) vary from site to site but are of relatively equal intensity on a regional scale
There is no regional specialisation for post-reduction, as the latter was not subject to geological imperatives.
P3/3 The inclusionary quality of the metal worked differs from site to site
The metal’s inclusionary quality, or equally how far it had been refined, depends on the phases already effected before the metal was obtained and so defines the phases no longer needing to be done. Certain articles needed excellent inclusionary properties - sword blade, sheet, craftsman’s tools... – while for others weak compacting was sufficient - andirons, anvil.... Thus to simplify, 5 qualities of metal may be defined: - Very bad, close to that of bloom, characterised by an impurity rate above 25 %. Depending on the quality of the reduction the blooms’ impurity rates can vary, but it is seldom below 25 %; - Bad, characterised by an impurity rate of about 15 to 25 % indicating a metal having received a first cursory compacting; - Medium, characterised by a porosity rate of about 10 to 15 %; - Good with an impurity rate of 5 to 10 %; - Lastly, an excellent inclusionary quality with an impurity rate of 0 to 5%. This quality is quite comparable to that of modern metals.
Organisation of production
P2/4 During the second Iron Age forging tended to be separated from reduction spatially
During Block I reduction was located both near to settlements and in the most remote zones (certainly due to the proximity or not of ore). As for forge activities, they were carried on within the settlement boundaries. Site numbers are pretty well equal between continuous production from smelt to forge (settlement) and discontinuous production (isolated reduction workshop). Nevertheless, the number of forge sites is higher than that of reduction sites. During Block II there seems to have been a growing separation between reduction and forge-work but reduction stayed close to the settlements; the proportion of forge sites increased. During Block III reduction became entirely separated from the forge and was now located outside the settlement in the specialised workshops. The proportion of reduction sites became very low in relation to forge sites.
P2/5 The intensity of forge production varies greatly from one site to another
It can be defined following several procedures. The first, quantitative, takes into account the absolute values for the slag found on the sites and gives data on the overall intensity of the activities - the quantity of metal worked. Weighting is necessary depending on how reliable the information is - erosion/density. In this way, the sites are first classified by taking into account the slag’s weight and the site’s area, and then classed down or up depending on the average situation. 7 degrees of intensity are then defined. The second, qualitative, takes slag refittings into account. This time data is supplied on the intensity of work sequences. The proportion of formless slag in relation to forge slag-cakes is used to characterise the refittings. In this way 4 refitting groups can be identified. The third relies on the cakes’ weight and represents the variations in the work sequences’ intensity. Again, 4 groups may be defined. We are now able to see certain sites have an overall (relatively) high production intensity but with sequences of middling work intensity (Condé-sur-Suippe) and that others have a low overall intensity but with sequences of very intense work.
Ratio between forge slag weight and the sites’ excavated areas
Ratio between formless slag and forge cakes
P3/4 The workshops may be isolated or correspond to a concentration of activities in a single place, or again to an artisanal quarter grouping interdependent activities together
Demonstrating the evidence of single or multiple workshop structures and of the spatial distribution of the finds according to the phase of the chaîne opératoire or the type of production enables the internal organisation of a site’s production to be shown. No rural site has supplied evidence of multiple workshops and they should be interpreted as isolated workshops. The case of Braine "La Grange des Moines" presents a distribution between the enclosure ditch and the ditch running alongside road leading up to the site depending on the activities, but a chronological succession in the deposits ought rather to be seen. On the other hand, the agglomerations present more complex structurings. The site of Bobigny and its three excavated plots does not seem to provide sufficient synchronicity to show the relations between the forge workshops. In the same way, the site of Acy-Romance is too eroded and the finds too deficient for work to be done on its internal organisation. Lastly, the oppida of Condé-sur-Suippe and Villeneuve-Saint-Germain seem to have had sectors of metallurgic activity, with interdependent specialised sub-sectors. The same organisation seems to have existed at Varennes-sur-Seine but the more precise archaeometric survey is still to be published.
Definition of the find groups
P4/1 During the second Iron Age an ever increasing division of the chaîne opératoire is apparent
During Block I the coexistence of reduction and forge work is a sign of a weak division of the phases in the iron producing chaîne opératoire. What is more, up till now and within the limits of the sites analysed, no example of specialised production has been found. However, the smiths seemed to have a global expertise with little interdependence. During Block III reduction seems to have been definitively separated from post-reduction. Moreover, the quality of the metal worked on the sites of a single region shows different levels of integration inside an acquisition/redistribution network of the raw material. These levels separate the sites in 4 groups, the first integrating their successors’ activities like Russian dolls. 1 - the sites producing or importing and then refining blooms. They then produce other more transformed semi-products or manufactured articles. 2 - the sites importing material in the form of crudely compacted semi-products which they then transform (more refined semi-products, objects). 3 - the sites acquiring the material in the form of semi-products of good inclusionary quality for manufacturing articles. 4 - the sites consuming and maintaining iron artefacts.
Division of the chaîne opératoire during Block I
Division of the chaîne opératoire during Block III
P4/2 The post-reduction sites are classified according to the finality of their production
Domestic and artisanal production may be distinguished by comparing the iron consumption of each period and the sites’ production intensity. The technical level certain activities required also ruled them out at a domestic level. The "social cost" involved in learning such skills and the weak economic incentive that low production offered seem incompatible. So domestic activity was certainly restricted to maintenance or simple recycling – above all for the earliest periods. The possibility of an itinerant artisanal activity also has to be taken into account; such an activity may be identified thanks to the relation between overall production intensity, the intensity of the work sequences, and the expertise. As for proto-industrial activities the organisation of the sites’ production and the activities’ intensity are the main criteria. Only the agglomerations could have been associated with such activities thanks to their internal organisation by quarters and to the interdependence of the various specialised workshops. Only the site of Varenne-sur-Seine, however, meets the requirement for change in scale of production.
Interpretation of the skills used on the sites studied
Global synthesis of the qualitative and quantitative data and interpretation of the activities
P4/3 During the second Iron Age commercial networks met the raw material needs of the regions that did not produce raw iron
Consumption of iron artefacts and the activities that produced them evolved in the same way throughout the zone of research. On the other hand, certain regions progressively became specialised in reduction activities and produced a good deal more than was needed locally. The other regions do not seem to have modified their scale of iron production from the beginning of the second Iron Age and so required imports of the raw material. The extensive communication network that covered the region facilitated this distribution. This situation is illustrated by studying socket bars. These bars are excellent quality - inclusionary and mechanical - semi-products and represent a specialised regional production from a region producing little raw iron (interface between the north-east and north-west zones). Chemical analysis of the inclusions has shown a multitude of origins and indicates local transformation of imported products.
Results of the inclusionary analyses on the socket bars
Chronological evolution of the activities
P5/1 During the second Iron Age iron-producing activities are found to have broadened in their scope: being purely artisanal in Block I, with domestic activities and artisanal quarters emerging in Block II, and proto-industrial productions in Block III
The diachronic results obtained in P4-2 must now integrate the chronological variable and need to be re-evaluated. For Block I - except for the obviously artisanal sites - the sites are difficult to interpret as places where domestic production took place. The weak maintenance needs and the presence of relatively large slag-cakes makes such an interpretation, in this context, hard to justify. They could thus have been momentary work places for "ambulant" craftsmen, or for a reduced and seasonal artisanal activity requiring only a little expertise. As for Block II the period’s transitory character does not make it easier to have a clear vision of its organisation. The site of Bobigny may well have been a place for diversified forge activities with distinct workshops, but the persisting doubt as to whether it belonged to a single complex makes it impossible to be sure. On the other hand, for Block III the iron consumption context may be an argument for revising certain interpretations downwards. In this way, sites originally viewed as places of momentary activity may now be seen as sites of a scant domestic or itinerant activity. So interpreting activities by chronological blocks shows, not only the increase in forge sites during La Tène, but also the diversification of organisation types between Block I and Block II - continuing more weakly between Block II and Block III.
Interpretation of activity types integrating the chronological variable
P5/2 During the second Iron Age artisanal and proto-industrial forge activities were located in high hierarchic rank sites
For each of the chronological blocks the most sophisticated forge activities – whether in expertise or production organisation – were located preferentially in sites of high hierarchic rank. This finding must be revised upwards, since the sites considered (i.e. with evidence of iron-production) do not reflect a proportionate cross-section of all the sites known for these periods. On the contrary, it is inverted, as the number of sites corresponding to elite residences is very much in the minority among all the known sites.
Relation between site hierarchic rank and activity type for Block I
Relation between site hierarchic rank and activity type for Block II
Relation between site hierarchic rank and activity type for Block III 1/2
Relation between site hierarchic rank and activity type for Block III 2/2
P6/1 In Block I production is weak and homogenous and destined for elites who assure direct or indirect control
All the regions studied seem to have been organised in the same way during this chronological block (within the limits of available data). Only the Sénonais was organised in this way more precociously. We have reduction sites – away from or close to where the craftsmen lived – sporadically producing their own raw material for the purpose of supplying the highest social categories with finished mostly prestige products. Certain sites seem to be momentary workplaces for smiths using their expertise for a single commission. The weak evidence for production seems to imply this activity was no more than on a local level. It is hard to say what share this production had in total consumption, but it seems, however, the role of long distance imports was far from negligible.
Locations of Block I sites
Theoretical scheme of the organisation of iron production in the north of the Paris Basin during chronological block I
P6/2 Block II was a phase of transition; the manufactured products spread more widely through society and the elites transformed the way they dominated the production
The primary production sites have only been found in the south-east of the Paris basin but they are thought to have existed in other sectors, particularly in the Pays de Bray from at least La Tène D1. Only the site of Cuy "Noslon" seems to have sheltered refining activities, and only because of the concomitant presence of reduction and forge remains. Other sites, however, must have been used for refining; for sites where only reduction took place were present. The reduction sites supplied a growing number of forge sites, which carried on an activity now cut off from the primary acquisition of the raw material. Article manufacture developed and a larger number of sites seem to have carried on real forge work - productive farms and agglomerations. These sites still remained the residences of a social and economic elite and their production constituted a new status among the aristocracy - an economic status no longer based only on wealth in land, but also on craft production. The purpose of this output now went beyond simply satisfying the needs of the elite, and its products were distributed at least locally, if not regionally. Domestic maintenance activities seem to have emerged just as iron tools for farming were used more broadly. Estimating how important imports were in this iron economy is still difficult; nonetheless, the meagre data on reduction activities may imply raw material imports may have been used to a considerable extent to meet the growing demand. Prestige good imports must have stayed relatively constant and may also have accompanied the supply in semi-products.
Location of Block II sites
Theoretical scheme of the organisation of iron production in the north of the Paris Basin during chronological block II
P6/3 During Block III a phenomenon of regional specialisation emerged and the iron economy (production/commerce) was dominated by the agglomerations and aristocratic farms
A separation occurred between the Sénonais and the other sub-regions studied. Reduction was much more intense there and specialised sites produced a quantity of metal for well beyond local needs. In parallel, a site like Varennes-sur-Seine "Le Marais du Pont" illustrates how production transforming this raw material was concentrated in the agglomerations, evidently with a view to medium and long distance exports. For the rest of the sub-regions production remained low, even if the Pays de Bray also had more productive reduction furnaces. In the north-east refining has only been found in the oppida which seem to have had a monopoly on the acquisition of this production that they then redistributed. More iron was consumed, evidently, than was produced locally; longer distance trade would appear to have become more important than in the preceding phases. Once the metal was transformed into semi-products the disparities between the sub-regions seem to have decreased. Certain sites, of higher hierarchic rank - aristocratic farms, open agglomerations and oppida – obtained the raw material to transform it and distribute it in their turn to the consumer sites. The latter carried out maintenance work more regularly than in former periods.
Location of Block III sites
Theoretical scheme of the organisation of iron production in the north of the Paris Basin during chronological block III
P7/1 During the 2nd Iron Age the organisation of production evolved, but its control remained in large part in the hands of the elite
Owing to wider diffusion of iron throughout society and a democratisation of article manufacturing activities the elites lost some of their control over production and the monopoly of consumption they may have had in Block I. They continued, however, during Block III to control iron-production economically by concentrating the most specialised artisanal activities and proto-industrial production in the sites of high hierarchical rank, and by centralising raw material trade in the agglomerations.
Acknowledgements
My thanks go to the scientific council of the CNRS and the INRAP for financing this research by means of a Doctor in Engineering's Bourse. I also thank the archaeologists who let me study their material: Ginette Auxiette, Lionel Boulenger, Pierre Broutin, Jean Bruant, Gaëlle Bruley, Thierry Dechezleprêtre, Sophie Desenne, Stéphane Gaudefroy, Frédéric Gransar, Colin Hazelgrove, Bénédicte Hénon, Bernard Lambot, Yves Lebechenec, Pascal Le Guen, Pamela Lowther François Malrain, Denis Maréchal, Stéphane Marion, Gilles Nazé, Patrick Pion, Bruno Robert, Richard Rougier, Antide Viand and George-Pierre Woimant. I also thank Philippe Fluzin, Christophe Dunikowski, and Sandra Cabboi for letting me use their illustrations.
I should also like to thank Valentine Roux for urging me to take part in the Arkeotek adventure, and Marie-Laure Senegas for her invaluable help.
Photographs and illustrations
© Sylvain Bauvais and Philippe Fluzin