The Beaker Salt Production Centre of Molino Sanchon II, Zamora, Spain

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Introduction

Salt is a mineral resource essential for human beings. It is used as a condiment to ensure our necessary daily intake, as a food preservative and as medicine, and it is important to the health of all livestock as a dietary supplement. It also plays a key role in leather tanning and cloth dyeing, among other industrial uses. Not surprisingly this white gold has been a highly valued commodity from prehistoric times onwards (Nenquin 1961; Denton 1982; Adshead 1992; Multhauf 1996; Kurlansky 2002).

Archaeological evidence, historical texts and ethnographic studies give insights into the methods employed for the collection and processing of salt in prehistoric Europe (Weller 2002b; Fielding & Fielding 2005; Monah et al. 2007; Weller et al. 2008). The usual techniques are mining of natural rock salt deposits (Barth 1982; Weller 2002a; Kern et al. 2009), or the evaporation of saline solutions, such as sea water (Hocquet & Sarrazin 1986; Escacena Carrasco et al. 1996) or natural brine obtained from inland saline water bodies (Riehm 1961; Morere 2007; Nikolov 2008; Weller et al. 2008). There is also an extraction procedure from salt-enriched plants, the final step of which requires the evaporation of water to precipitate salt crystals (Adshead 1992). Evaporation can be carried out by the heat of the sun or by boiling in open pans over wood fires.

Ethnographic analogies and archaeological evidence suggest that a number of stages are followed (Delibes et al. 1998) (Figure 1). Brine is poured into coarse ceramic containers placed over fires. The brine may be boiled dry to form a salt paste, or concentrated and transferred to small vessels placed on supports made of raw clay which stand over a hearth of glowing embers. The hot brine is then allowed to cool down gradually, permitting salt crystals to form. Once the crystallisation process is completed, the small pots are finally broken open in order to obtain hard and transportable salt cakes. This processing technique involves the utilisation of ceramic pots and earthen implements which differ hardly at all between those found in traditional salt production centres from ancient cultures and those from modern ethnographic contexts elsewhere in the world (Flad et al. 2005; Flad 2007).

The procedure leaves abundant archaeological evidence through its waste products in the form of ash, structural remains and briquetage. This latter term, coined by the French engineer de la Sauvagere when working at the production centre of Marsal in the mid eighteenth century AD (de la Sauvagere 1740), refers to the massive deposits of ceramic and unfired clay implements associated with boiling brine. After use these are broken and discarded onsite, generating refuse heaps that can range up to several metres in height. One of the most impressive accumulations of briquetage in prehistoric Europe is in the valley of the river Seille (Lorraine region, north-eastern France), an Iron Age salt production area where around 4 000 000[m.sup.3] of briquetage were dumped forming artificial hills up to 500m long and on the top of which were later built the urban centres of Marsal, Moyenvic and Vic-sur-Seille (Olivier & Kovacik 2006). This method of salt production disappeared in Europe when the Romans replaced the ceramic and earthen implements with lead pans, and briquetage no longer accumulated as a result (Julich 2005). Nevertheless, this traditional processing technique is still employed today in rural communities around the world (Tijania & Loehnert 2004).

We present here an example of European salt processing that can be dated back to the earliest Bronze Age, interpreted in detail with the help of ethnographic and archaeological parallels. Las Lagunas de Villafafila is a group of shallow saltwater lakes located in the province of Zamora in the north-west of Spain. The lakes are known to have been important for salt panning from at least the tenth to the end of the sixteenth century AD, when this activity was no longer profitable and was suddenly abandoned (Rodriguez 2000). …