What Was a Mortarium Used for? Organic Residues and Cultural Change in Iron Age and Roman Britain

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Introduction

The Roman ceramic mortarium is a robust, open form of bowl or basin, with a prominent rim and spout. The earliest mortaria recovered from Britain, which date to the later Iron Age, are continental imports discovered at sites located predominantly in the south- east (Hartley 1981, 1985). The frequency of these artefacts suggests that the scale of trade was initially low, perhaps incidental to other larger-scale trade. After AD 43, both imported and locally-made mortaria became increasingly common in Britain and two major centres began to dominate the market, one of which was situated south of Verulamium (St Albans) and the other in either Gallia Belgica or south-eastern Britain (Dickinson & Hartley 1971). By the later first century, however, imports had all but ceased, with only very low numbers of Gaulish mortaria present after AD 100 (Hartley 1973). Production was no longer confined to southeast Britain, with many other industries in the Midlands and further north producing and distributing mortaria alongside the still-dominant south-eastern production centres. From the later second century mortaria became more frequent and their distribution spread from a predominantly urban and military distribution to rural settlements. At rural sites in the north and west of the province of Britannia they are often found to comprise a relatively significant proportion of the overall ceramic assemblage (Evans 1995; Tyers 1996; Rush 1997; Cool 2004, 2006) even if the overall contribution of Roman-type pottery remained low.

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The earliest mortaria in Britain were straight (wall)-sided, often with incised lines scored around the interior providing a roughened surface (Hartley 1981, 1985; Parminter & Hartley 1996). These examples were usually not spouted. However, by the mid first century this version became obsolete, being replaced by the classic mortarium exhibiting a well-defined rim and flange, with coarse trituration grits replacing the internal scoring (Figure 1). Regional or industry-specific styles developed over time, including the Mancetter-Hartshill 'hammer-head' form and the Oxfordshire colour-coated wares imitating earlier Gaulish Samian ware imports. Although distinctive in form, the size, fabric and style of mortaria could vary widely; whilst most fall within the range of 20-30cm in diameter, miniature vessels and examples reaching 1 m in diameter are also known (Phelps 1923). Spouts, when present, could be flat and broad, a mere finger impression on the rim or a pierced hole through the vessel wall. Decoration was uncommon, but painted, stamped, incised or rouletted examples are known (Young 1973, 1977).

Heavy wear has been observed on some sherds (Hartley 1981, 1990; Parminter & Hartley 1996), which, combined with the presence of the trituration grits, indicate that the vessels may have been subjected to considerable abrasive activity. Sooting or burning is not ubiquitous but has been observed on sherds from a range of sites (Oswald 1943: 45-6; Hartley 1990: 194-5, 1999: 109; May 1996: 565).

According to Roman sources, mortaria were used to mix together a range of ingredients, including herbs and spices, meat, oil, fish sauce and wine, in order to prepare dishes such as rissoles, sauces and rnoretum (a kind of cheese-bread; e.g. Cato the Elder, De Agricultura 75-6; Dalby 1998). Apicius and Columella refer to a mortarium in the context of culinary preparations, often with reference to mixing or pounding of ingredients: "Put in a mortar pepper, caraway, coriander, asafoetida root, mint, rue; pound; moisten with vinegar, add Jericho dates, pour over some of the cooking liquor" (Apicius, de re Coquinaria; Flower & Rosenbaum 1958).

Other evidence for the use of mortaria can be derived from visual representations in contemporary artefacts, including a Roman figurine of unknown provenance on display in the Ashmolean Museum, Oxford. …