Evidence of Pollen and Plant Macroremains from the Sediments of Suburban Area of Medieval Tartu/Oietolmu Ja Taimsete Makrojaanuste Vordlev Analuus Keskaegse Tartu Eeslinna Alalt

Article excerpt

Introduction

In 1990-1994 rescue excavations at the building site of Postimaja (Post Office) at 7 Vanemuise Street were carried out in the suburban area of medieval Tartu (Fig. 1) directed by archaeologist Mare Aun (Aun 1994; 1995a; 1995b). In general, treatments of the primary structure of the settlement have been based on the oldest preserved town plans of the 17th century (Maesalu & Vissak 2002). Although the exact data concerning the formation of southern settlement outside the town wall is not available, it is rather likely that the suburban settlement was already developing by the fourth quarter of the 13th century at the latest (Heinloo 2006).

To engage an archaeobotanist to determine plant macro-remains from the deposits of early town was quite a common practice (Sillasoo 1997; 2005). Besides plant tissues, seeds and fruits, sediments frequently contain plant micro-remains--pollen and spores, providing extra information about the environment, economy and activities of the settlement. Only a few pollen analytical studies of medieval cultural layers were known from Europe at that time (cf. Vuorela & Hiekkanen 1991) as urban archaeology was among the latest fields of palynology. However, several waterlogged habitats from archaeological settings may prove suitable for pollen preservation, such as ditches, moats, wells, lynchets, post holes and sewers (Moore et al. 1991). As pollen and spores survive best in acidic and anoxic conditions, soils receive less attention from palynologists. The soil composition of cultural layers differs from the traditional material (peat, lake sediments and waterlogged sediments) used for pollen analyses. Oxidation and drying of soil lead to pollen corrosion and together with high charcoal dust concentration values it hampers the pollen analyses, so that the identification of taxa is often restricted (Vuorela & Lempiainen 1993; Vuorela et al. 1996). This has been, for example, the case with material from Tartu Dome Hill, where pollen was not found (Kihno 1994).

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Still, not all settlement layers have badly preserved pollen. Archaeobotanical investigations in medieval towns of Finland (Vuorela & Hiekkanen 1991; Vuorela & Lempiainen 1993; Vuorela 1994), as well as attempts made in this field in the suburban areas of medieval Tallinn (Kihno 1995a), encouraged the archaeologist Mare Aun to involve both an archaeobotanist and a palynologist in the project (Hiie 1995; 2002; Kihno 1995b).

Material and methods

Sampling

Samples for pollen and plant macrofossil analyses were collected by Ulle Sillasoo in May 1994. The sampling point was located in the southern part of the rescue excavations close to Vanemuise Street (Fig. 2). On the site of Postimaja both prehistoric and medieval cultural layers were discernible. Unfortunately neither of them was observed all over the investigated area; in the southern part of the excavation plot a medieval layer was established as the earliest upon the natural layers (?un 1995b).

About 1 m sample column was taken from the profile [4/i.sup.1] which can be divided into nine complexes (Fig. 3). At the base of the profile light sand crops out. The analysed cross-section begins with 0.18 m of brown peat followed by a 0.12 m well decomposed black layer of humus which is covered by a 0.38 m thick layer of organic-rich soil containing pieces of wood. On top of it, within 0.5 m, layers of sandy soil, fine brown sand rich in charcoal and coarse grey clayey sand with charcoal lay. The upper 0.35 m consists of rubble and infill.

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The samples range from the natural layers to the 14th-17th century cultural layers, the dating of which was based on archaeological finds (Aun 1995a). Two pollen and macrofossil sub-samples were analysed from the peat (Table 1), one from the layer of humus and two from the soil. …