Ballasting the Hanse: Baltoscandian Erratic Cobbles in the Later Medieval Port Landscape of Bruges

European Journal of Archaeology 2017, page 1 of 27

1 1 2 2 WIM DE CLERCQ ,ROLAND DREESEN ,JAN DUMOLYN ,WARD LELOUP AND 1 JAN TRACHET 1Department of Archaeology, Ghent University, Belgium 2Department of History, Ghent University, Belgium

The discovery of a remarkable group of vividly coloured rounded cobbles in the fields and monuments of the later medieval outports of Bruges has initiated a multi-disciplinary investigation into their function, provenance, and wider economic meaning. Geological analyses demonstrate that the stones are ballast of exotic lithological nature. A substantial number consist of glacial erratics collected from cobble beaches in the Baltoscandian area. Another group can be traced to north-eastern British coasts. The clustering of stones at Hoeke has drawn particular attention to the Hanseatic connection with Bruges and to the small harbour town of Hoeke, which hosted the staple of stockfish and various other Hanseatic activities. This article contributes to the discussion of ballast stones as a meaningful archaeological object category, especially when studied in a broader methodological context including archaeological, geological, and historical research.

Keywords: ballast, German Hanse, Bruges, Baltoscandian erratics, marine trade

LATER MEDIEVAL BRUGES AND ITS While the town was confined within its HARBOUR NETWORK walls, the commercial and portuary infrastructure extended well beyond, into the From at least the tenth century onwards, landscape to the north-east of the city. political and commercial power became From the late twelfth century onwards, centralized in Bruges, in the County of several small harbours emerged in the Flanders in Belgium. During the following immediate vicinity of Bruges along the centuries, Bruges evolved into an inter- Zwin tidal inlet, which was connected to national harbour that functioned as the Bruges via a smaller canal only navigable primary trading hub between the by smaller barges (De Smet, 1937; Leloup Mediterranean and northern and western & Vannieuwenhuyze, 2013). Damme, Europe. The town quickly expanded and Mude, Monnikerede, Hoeke, and Sluis all at its peak in the thirteenth century had became important medium- to small-sized some 50,000 inhabitants, including several outports, serving as transhipment points diaspora communities of foreign mer- for goods destined for the Bruges market chants and powerful financiers, as well as (Figure 1). leading political and artistic elites, becom- Although each of these outports was ing a ‘cradle of capitalism’ (Murray, 2005). legally an autonomous community with its

© European Association of Archaeologists 2017 doi:10.1017/eaa.2017.2 Manuscript received 11 July 2016, accepted 8 December 2016, revised 2 October 2016 Downloaded from https:/www.cambridge.org/core. Vakgroep Politieke Wetenschappen, UGent, on 24 Apr 2017 at 09:06:38, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms. https://doi.org/10.1017/eaa.2017.2 2 European Journal of Archaeology 2017

Figure 1. The late medieval harbour system of Bruges and its principal harbours and towns. Underlining indicates the presence of ballast stones.

own town rights, politically, financially, the small harbour towns even vanished and commercially the small harbours and now constitute a substantial yet largely largely depended on, and were monitored unknown part of the Flemish archaeo- by, Bruges (Fossion, 1992; Sosson, 1993; logical heritage. Dumolyn & Leloup, 2016). We can con- Bruges was economically and culturally sider Bruges’ commercial harbour and one of the most important cities of later related port society as an integrated ‘portu- medieval Europe, but, apart from some ary network’—a densely occupied and categories of ceramics, remarkably few urbanized medieval landscape stretching material proxies of its varied connections along the Zwin over a distance of nearly have been studied archaeologically (see e.g. 20 km between Bruges and the mouth of Hurst & Neal, 1982; Hillewaert, 1993; the Zwin near Sluis. The silting of the Pieters & Verhaeghe, 2009). This is par- inlet, as well as economic and political ticularly the case in the context of Bruges factors, led to the collapse of the system at as a Hanse Kontor within the so-called the end of the fifteenth century. Some of ‘Hanse Archaeology’, as it is for harbours

Downloaded from https:/www.cambridge.org/core. Vakgroep Politieke Wetenschappen, UGent, on 24 Apr 2017 at 09:06:38, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms. https://doi.org/10.1017/eaa.2017.2 De Clercq et al. – Ballasting the Hanse 3

such as London (Gaimster, 1999; Mehler, context. More specifically, this study 2014: 3214; Wubs-Mrozewicz, 2010). examines ballast as a valuable indicator of A cross-disciplinary study of material international mobility and exchange in the culture in harbour zones like that of harbours and port landscape of Bruges and Bruges is also particularly relevant for its wider northern European context. debates on maritime societies (Westerdahl, 1992, 2014) and for acknowledging the vital and multi-layered role material BALLAST AS AN ARCHAEOLOGICAL culture played in the later medieval com- OBJECT CATEGORY mercial, political, and cultural exchange networks, such as the ties that linked them Ballast is one of the most obvious object to the Burgundo-Aragonese spheres (De categories encountered in harbours for sea- Clercq et al., 2015) or the Hanseatic going vessels. It is also one of the most League (Immonen, 2007; Mehler, 2009, direct material evidences of international 2014, 2015; Gaimster, 2014). New, com- mobility within port societies. But little is prehensive research must therefore include archaeologically or historically known the socio-economic and cultural impact of about ballast, since it is often considered a important diaspora communities like the meaningless group of objects—‘ballast’ in Catalans, Genoese, and the so-called the figurative sense. The reason for this Easterlings or merchants of the German ignorance may be found in its general lack Hanse, noticeably present from the thir- of economic value, the paucity of written teenth century onwards in Bruges port- sources, and, above all, the varied and societies and the landscape (Beuken, 1950, often complex mechanisms for acquiring, Vandewalle, 2002). Such a study could be using, disposing, and re-using ballast. This conducted by using material culture to may be especially true of the Hanseatic assess the cultural impact of international League—initially a loose association of networks such as that of the Hanseatic merchants before it matured into an urban League (Gaimster, 2014; Mehler, 2009, league and commercial superpower in the 2015) on local society and culture. middle of the fourteenth century—which But, under the radar of high-status cul- organized its trade by using several har- tures, more mundane, everyday objects bours as stepping-stones between the floating just underneath the surface of a source and destination of commodities sea of conspicuous material culture may (Dollinger, 1998: 278–81). provide us with another valuable line of Buckland and Sadler (1990: 121), in a inquiry. These can help us assess transfor- thorough overview of ballast and building mations and interactions in everyday life, stones in maritime trade, critically high- often partially playing out at a discursive lighted these distributional problems by level. In this vein, we believe that the arguing that careful study of ballast stone study of material culture in these port from excavations and buildings may reveal societies should not be restricted to the trading connections, but that in the case identification of Hanseatic elements and of northern Europe the effects of multiple identity, but should include the interac- glaciations and the reshipment of ballast tions that existed between different mater- could lead to errors. Peacock (1998:13– ial cultures, thereby creating new complex 15) remarked on the neglected potential of lifestyles and material worlds within later ballast, considering it to be due to various medieval Europe. Our aim is to integrate difficulties in studying and interpreting these frameworks in a cross-disciplinary collections of such material. He outlined

some major conditions and constraints in Munthe (1942) had demonstrated the this respect: the ability to identify geo- value of biological indicators (molluscs) to logical and geographical signatures or pro- assess the ballast found in Fårö in North venances within assemblages of stones, as Gotland. These studies show that critical well as the fact that an assemblage may and cross-disciplinary research offers the represent a heterogeneous mixture caused greatest potential for addressing and even- by various natural and human factors. tually overcoming interpretational flaws Mehler (2015: 367–68) recently noted when examining large assemblages of that ballast was still being largely over- ballast stones. looked, adding that little is known about the ‘ballast-industry’ and the people who collected, transported, loaded, and EXOTIC STONES IN A STONELESS reshipped ballast. LANDSCAPE Stone ballast should indeed be approached cautiously as it may conceal Although ballast stones would be expected many complexities. But that does not in a port landscape like Bruges, the pres- mean it should be ignored as a valuable ence of stones of exotic geological nature and independent category of archaeo- has only recently been reported. A study logical objects. Westerdahl (1989: 110–17) of building materials used in the thir- acknowledged the great potential of ballast teenth-century church of Our Lady and its sites in his survey of Norrland. Buckland surrounding paths in the harbour town of and Sadler (1990: 118–19) convincingly Damme has revealed at least twenty differ- addressed the late-medieval link between ent types of natural stones, including— Hull and the Icelandic fisheries, underpin- uniquely in Belgium—pink granite and ning their work with a near-contemporary black amphibolite boulders (Debonne & account that explicitly mentioned ships Dreesen, 2015). These stones are geo- carrying stockfish from Iceland ballasted logically exotic to Flanders and neighbour- with Icelandic cobbles, which were subse- ing areas, and their morphology indicates quently re-used in the town’s paving; this a long stay in moving water. This suggests would suggest fairly direct trade. Similar that they were probably imported from observations could be made further south remote coastlines and were brought to the in King’s Lynn, Norfolk, where a cross- region of Bruges as ballast. disciplinary study identified a vast amount The same observation was made in the of Baltoscandian metamorphic and tower of the early Gothic church of Saint igneous rocks in the medieval town wall Guthago and Saint Quinten in the nearby (Clarke & Carter, 1977: 440; Hoare et al., village of Oostkerke, which served during 2002). In Belgium, a combined archaeo- the later medieval period as the principal logical-petrological study of unworked church for the nearby harbour of stone from the medieval fishing village of Monnikerede. Exotic cobbles were also Walraversijde (De Paepe & Pieters, 1994) found in the tower and footpaths sur- pinpointed the source of this material to rounding the church of Saint Bavo of the north-eastern or eastern coast of Aardenburg some 15 km to the north-east Britain. Most probably the ballast was of Bruges. This was an important medi- carried by returning herring-ships that eval place of pilgrimage and commerce called at ports in this area, as well as ships that briefly hosted the principal seat of the carrying coal from Newcastle-upon-Tyne Hanse in the thirteenth and fourteenth (De Paepe & Pieters, 1994). Much earlier, centuries following disputes with Bruges.

Moreover, excavations revealed similar exotic stones in the castle of the fifteenth- century new town of Middelburg-in- Flanders, located a few kilometres south of Aardenburg and east of Damme. These initial observations lead to sys- tematic screening for similar stones in monuments and archaeological sites within the Bruges port landscape. This study not only took into consideration monuments and infrastructure such as churches and paths, but also data from intensive field surveys of lost harbours sites. It revealed considerable amounts of boulders and cobbles of exotic metamorphic, igneous, and sedimentary lithological nature at Damme, Monnikerede, Westkapelle, Sluis, and particularly at the lost harbour site of Hoeke, where such stones were recovered by the thousands. The often vividly coloured, well-rounded stones occur in a preserved segment of a later medieval road and are found throughout the pathways surrounding the old farm that still stands on part of the Figure 2. Path cobbled with geologically exotic site (Figure 2). Ploughing of the rest of ballast stones at a farm standing on the lost (Hanseatic) harbour site of Hoeke. the lost town reveals new cobbles every year. Although found in the stoneless land- occurrence in buildings and infrastructure scape of northern Flanders, these remark- can therefore only be considered to able, colourful stones were clearly not represent a final recycling stage in a much primarily imported as building material. more complex cultural biography. The water-worn shape and the often very The stones’ spatial distribution within hard texture make these boulders and the port-system of Bruges seems to be cobbles unsuitable for the elaborately related to the evolution of the harbours sculptured and elegant Flemish Gothic that bordered the Zwin. No stones have architecture. Sandstone and limestone, been found along the Old Zwin system, which could be worked much better and located somewhat further to the north. was ideal for building, was already The phenomenon appears connected to imported in large quantities from the the latest Zwin, and hence with the floruit tenth century onwards from the Scheldt of the international trade in the region valley, the German Eifel area, or from between the twelfth and fifteenth centur- northern France and constituted the ies. The fact that no such stones have primary choice of building materials, along been uncovered during architectural or with brick. The rounded stones, on the archaeological investigations in Bruges other hand, were merely used in cobbled itself supports this hypothesis. The large paths, modest floors, or wall repairs. Their sea-going galleys and cogs needing ballast

did not reach Bruges, but remained in the better navigable outer ports, situated closer to the sea in the deeper water of the inlet, where their cargo was transhipped into smaller boats with lesser draught. These vessels then sailed to Bruges via the shallower western part of the Zwin and a canal extending eastward from Bruges to reach the tidal inlet in Damme.

ASSESSING THE GEOLOGICAL ORIGIN AND Figure 3. Proportion of the lithological groups of GEOGRAPHICAL PROVENANCE OF THE rocks identified among the cobblestones. STONE ASSEMBLAGE rather than a petrological approach using Methodology sophisticated mineralogical and geochemical tools. This descriptive method is rapid We investigated the most probable geo- and can be used for large quantities of logical and geographical provenance of the materials, but whenever this subjective stones, and related these to the local distri- determination fails, comparison with refer- bution pattern and historical context. ence material, complemented by examin- First, a random, non-exhaustive inventory ation under microscope if necessary, should of stones finds was made, resulting in a set be used. Hesemann (1975)andZandstra of 444 specimens of which the clear (1983, 1988)proposedapragmaticsubdiv- majority (over 90 per cent) came from the ision of the Fennoscandian provenance surface of the Hoeke site. The stones were areas to support the quantification of erra- grouped into lithological classes according tics and the statistical analysis of north- to their macroscopic properties. A selec- western European till deposits. The increas- tion of cobbles (about 10 per cent) was ing number of erratics collectors and stu- sliced and polished to allow us to better dents of erratics geology has resulted in assess their mineralogical properties. numerous well-illustrated digital resources1 Further, limestone boulders displaying with high-quality digital atlases a well as tubular burrows were selected for thin-sec- user-friendly keys for their determination tioning and additional microfacies and (e.g.Smed&Ehlers,2002). micropalaeontological investigation. All inventoried stones were measured and counted for their relative frequency and size distribution in order to help establish Lithology the mechanism by which they were transported. The analysis of the 444 cobble specimens The rocks’ exotic nature, specific litho- shows a broad lithological spectrum and logical spectrum, and overall morphology excludes local provenance. There is an pointed to the presence of so-called ‘erra- almost equal distribution between igneous tics’, i.e. cobblestones initially transported by glacial ice. For the study of such erratics, 1 http://www.kristallin.de/index.htm; http://www. zwerfsteenweb.nl; http://www.rapakivi.dk; http://www. a descriptive petrographic terminology is skan-kristallin.de; http://www.strandsteine.de/bestim preferentially used (hammer and handlens) mungsschluessel.htm

(34 per cent), metamorphic (28 per cent), (Neumann, 2012) are potential provenance and sedimentary (38 per cent) rock types areas. Yet the number of bryozoans in (Figure 3), but with a predominance of some of our flints could point to the bryo- red sandstones and irregular rounded flint zoan-rich chalks of south-eastern cobbles (Figure 4). The sedimentary rocks Denmark (Stevns Klint, Möns Klint) as a include different varieties of sandstones, potential source (Surlyk et al., 2006). micro-conglomerates, and flints, as well as However, additional palaeontological or limestones. Sandstones are fine- to coarse- geochemical investigation is required to grained, with greyish-green, beige to confirm this (Högberg et al., 2012). crimson colours. Granules and micro-con- Metamorphic rocks include various glomerates containing milky-white quartz dark-coloured gneiss, dark-grey micas- and red sandstone pebbles and arkosic to chists (rare), dark-green to black amphibo- greywacke-type sandstones also occur. lites (most frequent), augen-gneiss and Most of the inventoried sandstones are granite-gneiss (frequent), cream-coloured insignificant with respect to provenance, quartzites, and milky-white vein quartz. except for a medium-grained yellowish But their value as indicators of provenance sandstone displaying angular cross- is poor, especially compared to that of the bedding, whose foresets are impregnated igneous rocks. These represent the most with purplish iron and manganese oxides. exotic and the most significant part of the The latter can be tentatively assigned to lithological spectrum in our findings. They the Kalmarsund (Strait of Kalmar between consist of various types of felsic and mafic the Swedish mainland and Öland) sand- granites, porphyries, and many transitional stone. The limestone boulders consist of forms, most of which display vivid (e.g. grey, beige to pinkish-brown bioclastic red) colours. Extrusive rocks are only limestones, enclosing crinoids and small represented by frequent, dark-coloured solitary rugose corals. The presence of ignimbrites and very rare agmygdaloid subrecent borings made by pholads and basalt. Although many of these igneous bristle worms is most conspicuous. rocks could have come from anywhere Micropalaeontological analysis of these (e.g. Scotland, Brittany), some specimens limestones has led to detailed biostrati- have a restricted geological source area. graphic dating and a probable provenance While the lithological suite of the area, supported by biological evidence (see cobbles as a whole may not be indicative further below). of a single provenance, their well-rounded Grey-hued flints are quite common in shape, perfectly smooth surface (regardless the study material. Occasionally they of lithology), excellent sorting, and the enclose white-shelled echinoids or bryo- presence of subrecent bioturbations all zoan colonies. Bryozoan-bearing chalks point to a coastal pickup area: cobble enclosing flint are quite common and are beaches. Moreover, the presence of par- well exposed in the topmost Maastrichtian ticular key erratics or indicator cobbles (Cretaceous) and Danian strata (earliest points to a probable Baltoscandian origin. Palaeocene) of the coastal cliffs in south- The latter have a long transport history: eastern Denmark and the Rügen peninsula first they were eroded from the in north-western Germany. The high fre- Precambrian Scandinavian basement and quency and irregular shape might indicate overlying Early Palaeozoic formations and a nearby source and hence a shorter dis- then they were transported during the last tance for transport. The white chalk Ice Age by continental glaciers flowing Jasmund cliffs of the Rügen peninsula down from the Scandinavian mountains,

Figure 4. Frequency and size analysis of the inventoried lithological species among the cobblestones.

often over distances of hundreds of kilo- stones were subsequently reworked and metres (Smed & Ehlers, 2002). After sorted by sea currents or surges and rede- melting and retreat of the continental gla- posited along the coasts, creating cobble ciers, terminal and ground-moraines left beaches. Erratic cobbles and boulders behind huge amounts of glacial till, con- cover many beaches in the southern Baltic sisting of an unsorted mixture of clay, Sea region (Reinicke, 2011; Rudolph, sand, pebbles, cobbles, and boulders. The 2014), such as those bordering the former

Hanseatic towns of Lübeck, Rostock, phenocrysts) of both alkali feldspar and Stralsund (Rügen), and others. plagioclase, besides dark grey limpid quartz The presence of indicator or key erratics phenocrysts, within a dark brown or (Leit-Geschiebe in German) points to pro- reddish brown groundmass (Figure 5:3). venances within the Baltoscandian area. The exact geological provenance is The cobbles and boulders were deposited, unknown but is supposed to be located on and subsequently picked up, far away from the floor of the Baltic Sea, south-east of their original geological sources. We Stockholm, in Sweden (Zandstra, 1988; suppose that most of the sedimentary Smed & Ehlers, 2002). rocks (e.g. red sandstones), except the Red, dark brown to black porphyries, flints and limestones, derive from the often with an ignimbritic texture, Early Palaeozoic strata covering the crys- represent particular igneous rock types, talline Proterozoic basement rocks (Smed displaying a very fine-grained, hornfels- or & Ehlers, 2002). A description of some of flint-like groundmass with faint to visible the most distinctive key erratics found in banding (so-called ‘flames’) and containing our material follows. tiny feldspar phenocrysts, mostly without Larvikite is an igneous rock, more spe- quartz. Although some of the ignimbrites cifically a monzonite or alkaline syenite may derive from the Oslo area, the composed of quite large crystals of bluish- Swedish porphyries or ignimbrites are very grey feldspars (alternating layers of alkali conspicuous and quite common within the feldspar and plagioclases) with spectacular group of Baltoscandian glacial erratics reflections—the famous silver-blue irides- found in central and western Europe. cence or labradorescence. It has been These derive from a large volcanic field derived from the plutonic complex of near the village of Älvdalen (hence their Larvik (the Larvik Batholith) in the name: Älvdalen porphyries or ignimbrites) Carboniferous-Permian Oslo graben in located about 350 km to the north-west of south-eastern Norway (Zandstra, 1988; Stockholm. Different varieties are recog- Smed & Ehlers, 2002; Heldal et al., nizable based on their texture and colour 2008). Many varieties exist based on their (Wikström et al., 2014): the black Blyberg overall colour, but the alteration generally porphyry (Figure 6: 1), the dark reddish- results in discoloration and bleaching of brown Rännås porphyry (Figure 5: 5), and the rock (Venema & Egbrink, 2015). Our the brick-red Bredvad porphyry (Figure 6: specimens show a distinct light-silvery 4). The latter show numerous superficial grey colour (Figure 5: 1). pits caused by weathering and erosion of Kalmarsund sandstone is a cross-bedded the small feldspar phenocrysts. medium-grained sandstone belonging to a Other common red porphyries deriving series of sandstones probably derived from fromthesamevolcanicarea(Dala-Dalarna) the Early-Cambrian File Hadar Formation. are the Red Dala feldspar porphyry The red to purplish banding underlining (Figure 6: 2) and the Grönklitt porphyry this stratification is most conspicuous, (Figure 6:3).Thelatterisrichinfeldspar being due to the presence of iron oxides phenocrysts and contains pale-green spots (hematite) and/or manganese oxides filled with aggregates made of chlorite, (Figure 5: 2). This particular sandstone hornblende, and epidote crystals. comes from the area between the southern- Most conspicuous and vividly coloured most region of Sweden and Öland (Smed (often deep red) are the so-called &Ehlers,2002). Bothnian Sea quartz por- Rapakivi-type granites. These have charac- phyries contain many small crystals (micro- teristic large rounded and rimmed feldspar

Figure 5. Photographs of polished surfaces of sliced key erratics from the Bruges area. 1. Blyberg porphyry (ignimbrite) (sample HO-23); 2. Red Dala feldspar porphyry (sample HO-19); 3. Grönklitte porphyry (sample MON-2); 4. Bredvad porphyry (MON-3); 5. Pyterlitic Rapakivi granite (HO-58); 6. Red Småland Granite (HO-57).

crystals (ovoid alkali feldspars surrounded forming a distinctive repetitive pattern by a rim of plagioclase) and characteristic resembling cuneiform writing) (Figure 5: graphic textures (exsolved quartz typically 4). They are excellent indicators of

Figure 6. Photographs of polished surfaces of sliced key erratics from the Bruges area. 1. Larvikite (sample HO-28); 2. Kalmarsund sandstone (sample HO-40); 3. Brown Bothnian Sea porphyry (sample HO-18); 4. Rapakivi-type granite (sample HO-63); 5. Dalarna ignimbrite (HO-59); 6. Åland granite-porphyry or Ring quartz porphyry (HO-53).

provenance: they are thought to derive et al, 1989; Smed & Ehlers, 2002), from the Åland archipelago in south- although similar rock types also occur in western Finland (Zandstra, 1988; Ehlers the northern part of Sweden, i.e. in

Ångermanland. However, the latter lack the known south and south-south-west the characteristic deep-red to brown-red oriented transport directions of the continen- colour of the Finnish Rapakivi (Zandstra, tal glaciers (Smed & Ehlers, 2002)—clearly 1988). point to the south-western part of the Baltic Closely related to the Rapakivi-granites Seaasthemostplausiblepickupareaforour are the Åland granite-porphyries and pyter- the stones in our inventory, such as the lites or pyterlitic Rapakivi-granites, also coastal areas south of Skåne, the eastern derivedfromtheÅlandIslands.Redring- coast of Denmark, and the northern German quartz porphyries or Åland granite-porphy- coastline between Lübeck and Stralsund ries are particular granites displaying con- (Figure 7). spicuous thin black rims of hornblende Besides erratics and flints, several lime- crystals that surround the dark grey stone boulders and cobbles are present in (‘smoky’) quartz crystals, next to large our study material. The latter are medium rounded alkali feldspar crystals (Figure 5:6). grey to liver-coloured, fine-grained crin- Agraphictextureisalsopresent.Pyterlites oidal limestones, also enclosing solitary or pyterlitic granites (Figure 6:5)arechar- corals. Moreover, several of the boulders acterized by the development of coronets show large subrecent tubular burrows (‘necklaces’ of beads) of small idiomorphic created by clams such as pholads, pointing quartz crystals around the large feldspar to a seashore environment (Figure 8:1,2) crystals (Zandstra, 1988;Smed&Ehlers, Thin sections of the crinoidal limestones 2002). allowed us to undertake a detailed micro- A series of red- to pink-coloured gran- facies analysis and a good assessment of ites with eye-catching blue or bluish-grey their biostratigraphic age. Microscopically, quartz crystals and red K-feldspars are the limestone boulders consist of bioturb- known as Småland granites (Figure 6: 6). ated bioclastic wackestones and pack- The blue colour of the quartz crystals is stones, containing echinoderms, fenestellid enhanced through polishing or wetting the bryozoans, thin-shelled ostracods, brachio- stone slabs (Zandstra, 1988;Smed& pods, calcareous algae, plurilocular foram- Ehlers, 2002). inifera, and rugose corals. Key solitary Dark-grey flints are frequently mixed corals (Siphonodendron pauciradiale) with the above crystalline rocks. Their (Figure 8: 5) and index plurilocular foram- form is generally less regular and less well- inifera (Eostafella ikensis, Bradyina rotula, rounded than that of the igneous and Howchinia sp., and Archaediscus karreri) metamorphic stones, suggesting a nearby (Figure 8: 3, 4, 6) clearly indicate a Lower source area. The cobble beaches of south- Carboniferous geological age, more specific- eastern Denmark and northern Germany ally the Late Visean. The foraminiferal are particularly rich in flint cobbles. The microfauna indicates the standard latter are always mixed with the colourful Microfossil Zone MFZ14 (former V3b igneous rock cobbles and boulders, dis- gamma zone) or the Late Asbian substage playing all the characteristics of reworked of the Lower Carboniferous (Poty et al., Baltoscandian erratics (Reinicke, 2011; 2006). This biostratigraphic age is corrobo- Rudolph, 2014; Rudolph et al., 2015). rated by the occurrence of Siphonodendron The combination of a rich and exotic litho- pauciradiale,acoralspeciesalsofoundinthe logical spectrum, the presence of key erratics British Asbian. pointing to various geological sources in The most probable provenance region Norway, Sweden, and Finland, and the rela- of these limestone boulders is the coastal tive abundance of flints—taking into account area of Northumberland, for instance near

Figure 7. Simplified map of the Baltoscandic region with locations of provenance areas of identified key erratics (1–6) and flints (7: probable source area) within the material from the Bruges area.

Berwick-upon-Tweed. Here, the outcrop- evidence therefore suggests that the lime- ping Asbian limestone beds belong to the stone boulders were picked up along the Tyne Limestone Formation of the shore, in or below the intertidal zone of the Yoredale Group (Waters et al., 2011; coastal cliffs of Northumberland, probably Dean et al., 2007). A link with a coastal near Berwick-upon-Tweed (Figure 9). area is also suggested by the boulder morphology (rounded nature) and by the presence of numerous pholad borings in Morphology and size distribution the limestone boulders (Pholas dactylus, commonly called piddocks or angelwings) While the petrography of indicator erra- which point to an area with a coastal, 2 tics allowed us to identify their original intertidal habitat (MarLIN ). The com- area of geological provenance, the bined geological and modern biological morphology of the cobbles is quite characteristic of a high-energy aqueous 2 http://www.marlin.ac.uk/species/detail/1403 environment such as cobble beaches.

Figure 8. Macroscopic features and carbonate microfacies analysis of limestone boulders. 1. Limestone boulder surface strongly bioturbated by pholads. 2. Cut limestone boulder showing tubular borings of pholads (length of burrows about 25 mm). 3. Thin section micrograph of a bioclastic wackestone showing plurilocular foraminifera, including Bradyina rotula (Eichwald) (large specimen in the middle) and Howchinia sp. (tiny foraminifer at the left). 4. Thin section micrograph of a bioclastic wackestone showing small plurilocular foraminifera: Archaediscus karreri Brady. 5. Thin section micrograph of a bioclastic wackestone showing transversal sections of the small rugose coral species Siphonodendron pauciradiale (McCoy). 6. Thin section micrograph of a bioclastic packstone with the plurilocular foraminifer Eostafella ikensis Vissarionova. All micrographs taken with parallel polarized transversal light.

Moreover, an overall size distribution excellent sorting (Figures 5 and 10). analysis of the selected cobbles in func- Cobble diameters vary from 5 to 40 cm tion of their lithology demonstrates with an average of about 12 cm for all

Geological discussion

There are no crystalline rocks such as those described above in Belgium. The nearest coastal outcrops of crystalline rocks are located in north-eastern England, Scotland, or Brittany. However, the presence of particular key erratics suggests a Baltoscandian provenance. Furthermore, particular limestone boulders containing characteristic fossils point to the north- eastern English coast as an additional source. The import of non-indigenous ballast and building stones has already been reported in the medieval fishing village of Raversijde near Ostend (De Paepe & Pieters, 1994) and a probable fifteenth-century link with the north-eastern British coast was demonstrated there. In this case the Scottish Midland Valley and the British Tertiary Volcanic Province (e.g. the Inner Hebrides) as well as the Grampians have been suggested as the Figure 9. Map of the UK showing the geological probable provenance areas for the igneous distribution (extension) of Asbian limestones (blue) in north-eastern Britain and the modern and metamorphic rock types respectively. distribution of Pholas dactylus (green). Based on The morphological characteristics of the data from the BGS (British Geological Survey) ballast stones also indicate a stony coast- and marLIN (the Marine Life Information line as the most probable pickup zone. Network). Hoare et al. (2002) reported re-used bedrock ballast stones as construction stone varieties. The morphology of the material in King’s Lynn’s medieval town stones (overall shape, smoothness, and wall. It was the first comprehensive survey roundness), in combination with their of an impressive number of ballast cobbles. quite exotic nature and the good sorting, The cobbles’ considerable lithological points to a combined glacial transport variety was sufficiently distinctive to make with subsequent sorting and rounding by it possible to identify their provenance. surges along seashores. The average size Besides sedimentary rocks native to the of the cobbles indicates both good district, several Baltoscandian indicators natural sorting (by surges and waves) and were found, including Rapakivi-granites, human sorting by handpicking along rhomb porphyry, Bredvad porphyry, helle- beaches. The size and high mass density flint, Bothnian Sea porphyry, and of the cobbles creates a selection of Ordovician red orthocerate limestone. stones which are suitable for stacking Many of the wall cobbles are of basaltic, when used as ballast. Cobble beaches porphyritic, and metamorphic origin, were indeed an important primary source which, while not identifiable to geological of medieval ballast, particularly around sources, may also be expected to accom- many Baltic ports (Hoare et al., 2002). pany the Baltoscandian indicators. The

Figure 10. Size distribution (cm) of the measured cobblestones.

most satisfactory explanation for the pres- gneisses such as Rapakivi-granites. As in ence of these water-worn Baltoscandian the case of King’s Lynn and the Bruges cobbles in the town wall of King’s Lynn is portuary area, most of the erratics have a that they formerly served as ballast, and well-rounded shape suggesting that they the authors concluded that there was a were subject to marine abrasion in a high- possible link with the coast of western energy beach environment. However, the Estonia. Scandinavian erratics are less frequent The morphological-petrographical char- than the ‘local’ or indigenous erratics acteristics of the re-used bedrock ballast derived from the West Sussex coastal plain stones at King’s Lynn are quite similar to beaches. those of the area of late medieval Bruges. The occurrence of analogous material in The occurrence of common key erratics the UK and in Belgium points to the (such as Rapakivi and pyterlitic granites, import and re-use of well-sorted and Bredvad and Bothnian Sea porhyries), water-worn cobbles picked up on Baltic their conspicuous water-worn shape, and Sea cobble beaches. Many of the inventor- excellent sorting, all point to a common ied cobbles are of basaltic, porphyritic, and source: the cobble beaches of the Baltic metamorphic origin, which, although not Sea. Interestingly, both in King’s Lynn identifiable to geological source, may be and in the Bruges area, these key erratics expected to accompany the Baltoscandian represent only a very small percentage of indicators (Hoare et al., 2002). Although the total material (one per cent in the case crystalline rock types such as granites, of King’s Lynn, possibly a few per cent ignimbrites, porphyries, quartzites, gneiss, in our study), hence the importance of amphibolites, mica schist, etc. could derive a detailed investigation and the search from less distant sources, such as the for specific exotics among the re-used coastal areas of Scotland or Brittany, the cobblestones. presence of particular but rare key erratics Examples of a variety of Scandinavian and significant amounts of flint point to a rocks have been described in buildings pickup area located in the south-western from Littlehampton (West Sussex, south- Baltic Sea, such as the cobble beaches ern England), notably in the walls of the south of Skaane and along the coast of United church, where they are mixed with northern Germany. Moreover, microfacies flint (Birch & Cordiner, 2014). These are and palaeontological-biological evidence very distinctive coarse-grained granites and suggests the additional import of ballast

stones from the north-eastern coast of community of foreign merchants in England (Berwick-upon-Tweed area) into Bruges (Henn, 1989; Vandewalle, 2002; the Bruges area. Greve, 2012; Murray, 2012). The Hanseatic ‘nation’, as the privileged communities of foreign traders in Bruges ‘IN NOVAM VILLAM DE DAM’: were known, had a so-called Easterlings BALTOSCANDIAN BALLAST IN A House in Bruges, a guildhall, but it was FORGOTTEN HANSEATIC SETTLEMENT IN only in use from 1478 onwards (Devliegher, FLANDERS 2000). Before that, Hanseatics lived among the local population. Murray (2012: 183) From a quantitative and distributional argues that, as a consequence of opposition point of view, the massive occurrence of from Bruges, Hanseatic merchants never northern ballast stones at the Hoeke site established a separate merchant enclave stands out when compared to the other with immunity under the law, thus deviat- port sites within the Flemish port system, ing from the ‘colonisation strategy’ applied notably those located closer to Bruges. in the Kontors of London, Bergen, and Should we interpret the Baltoscandian Novogrod. However, at some point during stones as an indicator of the firmly estab- the second half of the thirteenth century, lished trade links that existed between the Hanse merchants tried to do so. While northern Europe and the Bruges port it was never a Hanse colony sensu strictu, network during the later Middle Ages and there was an important and clustered between the harbour of Hoeke and the Hanseatic presence and institutional inter- Hanseatic trade network in particular? vention at Hoeke. Merchants from Cologne first appear in Indeed, between 1252 and 1255 the Zwin region around AD 1160 at important negotiations took place between Letterswerve, the Bruges outport later the representatives of the German towns known as Damme (Verhulst 1998; of Lübeck and Hamburg and Countess Verhulst et al., 1998). During the thir- Margaret of Flanders (Kiesselbach, 1900; teenth century, as Bruges’ market was Stein, 1903; Henn, 1989). They explicitly steadily expanding, traders from other expressed their will to construct a perman- towns, most notably Lübeck and ent trading settlement for German mer- Hamburg, seem to have increasingly fre- chants, a novam villam de Dam as they quented Bruges’ harbours. These mer- called it: a new town of Damme. Damme chants obtained privileges from the was an important outer port of Bruges, Countesses and Counts of Flanders in created by the Count of Flanders around 1252–53, 1280–82, 1307, and 1309 and 1180. It was a major harbour for the wine established a durable and unified trade and had a crane that was owned, Hanseatic trading community in Bruges along with the quays, by the city of during the first half of the fourteenth Bruges. The Germans’ request was century. The sources sometimes refer to straightforward: they wanted to build their them collectively as merchants from own, new trading town. In an unsealed Allemaigne and, somewhat later as charter, Countess Margaret effectively Oosterlingen—traders from the towns approved the German request and that, around the middle of the fourteenth assigned the universi mercatores Romani century, constituted the German Hanse. imperii ‘an area between our harbours of By that time, probably together with the Damme and Mude and to the side of the English, they made up the largest water of the Zwin’, specifying that other

Flemish and foreign merchants would also although there was no Hanseatic immun- be allowed to settle there. This area is de ity from Flemish courts, the Germans facto situated in the territory of Oostkerke, already had consular jurisdiction for con- an old and large fief to the north-east of flicts among themselves in Hoeke, as they Bruges in whose territory lie the harbour and other ‘nations’ would later also have in sites of Monnikerede and Hoeke. In the Bruges. The Hamburg maritime law of absence of a formal (sealed) charter con- 1292 also mentions similar practices in firming the countess’ approval or any other Oostkerke: a representative, the payment document attesting to the establishment of of a fee, and a Sunday morning meeting this new town, historians assumed the plan to settle commercial conflicts. However, never actually materialized (Stein, 1903: ‘Oostkerke’ clearly refers to Hoeke as well. 67–92; Murray, 2012: 183). Merchants from Bremen also frequented Yet historical sources from the second Hoeke but it is unclear if they had a separ- half of the thirteenth century do refer to ate Hanse (Kiesselbach, 1900; Henn, the presence of Hanseatics in Hoeke. It is 1989: 59). Twenty years earlier, in the possible that this so-called novam villam 1270s, Heinrich von Coesfeld (possibly a de Dam, even if it was never founded in German) had bought a house in Hoeke to exactly the way the charter described, was establish a ‘hospital’, an almshouse that in fact Hoeke (e.g. Bonte, 1987), and this also probably served as a guesthouse for hypothesis deserves more attention. poor merchants; he also acted as the exe- Hoeke, literally ‘the corner’, was indeed an cuter of the testament of another German ideally located site within the area desig- named Heinrich, who bequeathed 250 nated by the countess in 1252, as it lay in pounds Flemish ‘groats’ to build a the northernmost corner of the Oostkerke St. Jacob church at Hoeke; and in 1402 an territory, positioned as close as possible to ‘Easterlings’ House’ is mentioned in Mude and the sea. This must have given Hoeke (Stein, 1903:92–94; De Smet, it the important advantages of deeper and 1937: 137–39; Henn, 1989:58–60; better navigable access for tall ships. Rössner, 2001: 46). The 1292 maritime law of Hamburg All this illustrates the Hanse merchants’ states that the Hanse’s seat in Flanders will and ability to establish a principal was in Oostkerke and thus exactly in the node in the local network where they de area the countess had stipulated: ‘and as facto centralized important functions, next such the Hanse shall be held in Ostkerke to their more scattered presence in Bruges, in Flanders and in no other place’ Damme, and later in Sluis. ‘New Damme’ (Kiesselbach, 1900: 62). The maritime law was, however, never intended to become a of Lübeck dated 1299 is the first to expli- Hanse jurisdiction, such as the Steelyard citly mention Hoeke (to deme Hoke) as the of London, the Peterhof of Novgorod, or seat of the Lübecker Hanse (Kiesselbach, Tyskebryggen in Bergen, as the charter 1900: 67). According to the Lübeck mari- mentions that the countess retained com- time law, all merchants from that town plete jurisdiction for herself and her native who had moored their ship in Hoeke or aldermen. Moreover, even if Hoeke can be elsewhere along the Zwin had to pay a fee identified as New Damme, the foreign to the local Hanse organization and attend merchant community was certainly not the ‘bench’ (banck) with a local Hanseatic exclusively Hanseatic. Judging from the representative (olderman) every Sunday. variety of names mentioned in a 1299 This court mediated conflicts between the legal document, Hoeke had a diverse German merchants, which implies that, population, with many Germans as well as

a number of Iberians and some people fourteenth century. The town continued from the south of France (Gilliodts-Van to function as an outport in the Bruges Severen, 1891: 187–90; Bonte, 1987). metropolitan system of the later Middle Iberian merchants from Castile, Ages but became insignificant by the end Aragon, Navarre, and Portugal had also of the fifteenth century (Bonte, 1987; been trading in Bruges and appear in the Henn, 1989). sources from the 1230s onwards. In 1279, We believe that there is firm evidence these Iberian traders, and also some south- to reconsider the Hanseatic presence at ern French merchants joined by the Bruges in a much broader way, extending Germans in 1280, collectively opposed the notion of the ‘commercial metropolis excessive taxation and fraudulent practices, of Bruges’ to the whole port landscape, temporarily moving to the nearby town of with initially Damme, then Hoeke, and Aardenburg before finally managing to later on Bruges and Sluis, as the main have the abuses abolished and returning focal points of a Hanseatic community their wares to Bruges in 1282 (Finot, that had apparently completely woven 1899; Maréchal, 1953; Poeck, 2001). The itself into the complex tapestry of Bruges’ Hanse was still a fledgling international port landscape and society. Most import- organization at that time, and many antly, German merchants concentrated Hanseatic merchants in Flanders still their activities on Hoeke on a fixed basis resided in the outport of Hoeke and not from the 1270s onwards and lines of con- in Bruges itself. Following currency con- tacts were established between the site and flicts and negotiations with the govern- the other Hanseatic towns in the ment of Bruges and the Count of Baltoscandian area, alliances that the clus- Flanders, and new threats to move their tering of ballast stones seem to document. staple to Aardenburg, the Hanse obtained even more extensive privileges in Bruges in 1309, moving their consular court for COGS,STONES, AND SAND internal business affairs and their staple to the commercial metropolis itself. Around The piling up of Baltoscandian stones the middle of the fourteenth century they and, to a far lesser extent, English lime- were officially organized in a ‘Kontor’.It stones at Hoeke could indicate that large seems that this marked the Hanseatic ships moored at Hoeke, and that their merchants’ final settlement in Bruges as a commodities were transhipped onto formally and corporately organized com- smaller barges that then headed towards munity for the next two centuries. Bruges in the shallower waters of the Moreover, the transhipment of merchan- Zwin tidal channel. Documentary sources dise increasingly took place at the deeper refer to the staples of stockfish, salt, and and more easily accessible harbour of cereals, along with various nautical sup- Sluis, founded by the Flemish count at the plies (masts, shipwood, tar, ropes) and a end of the thirteenth century. While the shipyard at Hoeke. To repair ships, the period around 1300 may have been ballast had to be taken out. Additionally, Hoeke’s heyday as a merchant community, considering the low density of dried fish, the small port clearly became less import- ballasting the ships transporting it to ant to the German merchants, only func- Hoeke must have been essential to guaran- tioning as a mooring and repair place, and tee a stable and safe journey. The ships as a permanent place of residence for a could presumably take the heavier com- smaller number of them during the modities such as wine or cloth as return

freight. Hence, alongside a shipyard, the (Finot, 1899: 103). It seems therefore presence of Baltoscandian ballast stones clear that local sand was brought in as could be explained by the very nature of ballast to the Bruges area and presumably its stockfish trade. this was also the case for the Hanseatic As for explaining the occurrence of cogs returning home. Asbian limestone, trade in wool and other In one of the rare archival documents goods from Berwick-upon-Tweed to dealing with ballast, dated 4 October Flanders is well established (Donnelly, 1408, an agreement regarding ballasting 1999). Following the trail of the was noted between the councillors of Baltoscandian erratics back along the the Count of Flanders and representatives eastern British coast, we can also reason- of the German Hanse (Gilliodts-Van ably argue that ships with merchandise, Severen, 1904: 467). It recalls how the e.g. fish from Skaane, called at Berwick- Alemaignen merchants would receive a fine upon-Tweed before continuing further of 3 pounds for each boat of ballast they south-east along the British coast, using took from the land of Cadsand or from harbours such as Hull (Buckland & the dike near the castle of Sluis. The Sadler, 1990: 118) and King’s Lynn count would obviously not permit the vital (Hoare et al., 2002), eventually to sail infrastructure protecting his castle and the into the Zwin estuary. Scottish trade with hinterland to suffer damage in the process. the Baltic regions and northern Germany Instead, the Hanseatics were assigned was also particularly well developed three specific places where they were (Ditchburn, 1988, 1990). allowed to take ballast sand: one at Another, final explanation for the pres- Wulpenhoek, one at Reighersvliet, and one ence of the stones could be that the ships ‘on the ground maintained by the lord Jan left them in Hoeke because they took of Oostkerke’. The first place lay along a another kind of ballast with them, pre- network of small tidal creeks connected to sumably more valuable or more useful the Zwin, while the latter two were in an than cobbles. Documentary evidence pro- area close to Hoeke, which was in the ter- vides important information on the bal- ritory of Jan, lord of Oostkerke. One field lasting of ships leaving the Bruges port in the area is still commonly known as ‘the landscape. A decree issued by Count sandpits’, a pre-sixteenth-century place- Louis of Male in 1367 stipulated a price name (‘De Zandpitten’ on Figure 11). In of 4 pennies Flemish groat for each boat view of the location of these ballast sand of sand brought as ballast to Castilian quarries, we can reasonably assume that ships (Finot, 1899:97–105). Of course the shipment of ballast was done in small sand is ideal as ballast since it has a large boats with little or no draught, using the weight in mass and fills in the smallest network of creeks to bring the sand to the corners, allowing more space for commod- sea-going ships moored in the Zwin. ities to be taken on board. The ballasting Documents show that the permitted was to be done by a specific professional weight was equal to that of two barrels of group called ballastvorers (‘ballast carriers’). wine per boat, and one English pound It was also decided that no fines would be and 4 Flemish groats had to be paid per issued for ballasters and shippers spilling boat brought in (Gilliodts-Van Severen, sand if they took the precaution of span- 1904: 467–68). In response to complaints ning a large sail between the ballast ship about the ballasters, in 1425 the Four and the ship to be ballasted in order to Members of Flanders confirmed that the prevent sand from dropping in the water Hanseatic merchants ‘could collect their

Figure 11. Known extraction locations for ballast sand in the Zwin area (symbol: tools). The under- lined locations are assigned areas.

ballast themselves to their best benefit’ inbound transport by sea. The paleonto- (Hanserecesse, 1893: 564). logical study of the shell fossils led the Additional support for the hypothesis authors to conclude that an intertidal that Flemish sand travelled to the marine sand flat close to a small estuary Hanseatic homeland as return ballast can was the site of primary deposition. be found in a sand deposit in Wismar, a Subfossils indicate a southern North Sea Hanseatic harbour in the Lübeck- origin, which includes the Zwin area. The Hamburg-Stralsund area, where most of high carbonate content of the sand may the stones also originate (Ansorge et al., have made it useful for making mortar. It 2011). The researchers studied a four- seems highly plausible, though surprising, teenth-century deposit of 20 to 30 m3 of that ballast stones collected on beaches in sand found during excavations in the the Baltoscandian area were left thousands harbour. The almost pure quartz sand of kilometres to the south in the Zwin contained marine shells alien to the Baltic area, sometimes in exchange for purchases area, indicating their exotic nature and of local sand.

CONCLUSION:RECONSIDERING BALLAST ACKNOWLEDGMENTS IN THE BRUGES HARBOUR NETWORK AS A PROXY FOR TRADE NETWORKS This study was made possible by the help of many people. Mr Tilleman and Mr Strubbe, Although ballast must have been a fre- farmers in Hoeke and Monnikerede, kindly quent aspect of port societies like Bruges, granted us access to their fields and farms and studies dealing with its role and function allowed us to collect ballast stones. We grate- are still very rare. When analysed in a fullyacknowledgetheadviceofProf.Emeritus cross-disciplinary way and situated in its R. Vinx (University of Hamburg) and proper archaeological, historical, and geo- M. Bräunlich (erratics specialist, Hamburg) logical context by looking at indicator regarding the identification of erratics, and rocks, ballast stones are a valuable tool and Prof. D. Ditchburn (Trinity College, Dublin) object category that add to the under- regarding the Scottish harbours. Dr standing of later medieval sea-borne D. Vachard (University of Lille) and Dr networks. J. Denaeyer (University of Liège) helped with The occurrence and re-use of exotic the palaeontological identifications and bio- ballast stones in the Bruges area, and at stratigraphic dating. J. Eggermont sliced the the site of Hoeke more particularly, is well large boulders, T. Clerbaut assisted with the established. The stones were picked up spreadsheet work, S. Reniere helped us with along cobble beaches of the Baltic Sea photography, and J. Angenon provided coast. The common presence of flints artwork. The abstract was translated into mixed with the colourful crystalline erratics German by J. Brettschneider and the English points to the south-western part of the revision of our text was undertaken by Baltic Sea, such as the coast between Thomas Donald Jacobs. The authors wish to Lübeck and Stralsund (northern Germany), thank the reviewers for their useful thereby corroborating the historical evi- comments. dence of intense Hanseatic trade with Bruges. In the case of Hoeke, the stones definitely add to the debate concerning this REFERENCES harbour settlement in the Bruges port landscape. Hoeke hosted an important cluster Ansorge, J., Frenzel, P. & Thomas, M. 2011. of Hanseatic activities, certainly in the late Cogs, Sand and Beer: A Palaeontological thirteenth century and the beginning of the Analysis of Medieval Ballast Sand in the Harbor of Wismar (Southwestern fourteenth. A smaller set of ballast stones Baltic Sea Coast, Germany). In: H.-R. was collected at the foot of the north- Bork, H. Meller & R. Gerlach, eds. eastern English coastal cliffs, testifying to Umweltarchäologie – Naturkatastrophen und the trade link between Berwick-upon- Umweltwandel im archäologischen Befund Tweed and Bruges’ ports. Finally, it seems (Tagungen des Landesmuseums für Vorgeschichte, 6). Halle: Landesmuseums that the Baltoscandian erratic cobbles were für Vorgeschichte, pp. 161–73. left on land in Flanders in exchange for Beuken, J.H.A. 1950. De Hanze in Vlaanderen. sand, to be used as ballast and to be re- Maastricht: Van Aelst. used in Hanseatic towns in the north. Birch, R. & Cordiner, R. 2014. Building Commercially, this was a most effective Stones of West-Sussex. Privately published, ISBN: 978-09551259-1-1. trade transaction for the Hanseatics, since Bonte, G. 1987. Duitse handelsbetrekkingen ballast had become a saleable item, a com- met het Zwin. Rond de Poldertorens, 29(1): modity in itself. 1–9 and 29(3): 150–65.

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Roland Dreesen is a geologist. After a short at Ghent University and the Vrije career in research (Palaeozoic sedimentary Universiteit Brussel. His earlier investiga- geology and biostratigraphy) he moved to tions focused on the history of the medi- applied and economic geology in 1985, and eval portuary network along the Zwin was based in Liège (ISSeP) and then Mol estuary and its constituent towns. His (VITO). His research activities covered PhD research examines the socio-eco- several topics within coal geology, geo- nomic topography of late medieval cities energy, and materials characterization. His in Flanders and Brabant, primarily Bruges current research interests include proven- and Mechelen. ance studies of historical building and dec- orative stones and geoheritage. Address: Department of History, Henri Pirenne Institute for Medieval Studies, Address: Department of Archaeology, Henri Ghent University. St-Pietersnieuwstraat Pirenne Institute for Medieval Studies, 35, 9000 Gent, Belgium. [email: ward. Ghent University, St-Pietersnieuwstraat 35, [email protected]] 9000 Gent, Belgium. [email: roland. [email protected]] Jan Trachet is a doctoral student working on a Research Foundation Flanders Jan Dumolyn is a senior lecturer in medieval (FWO) Research Project that aims to history. He specializes in the political and unravel the medieval development and socio-economic history of the medieval Low topography of Bruges’ outer harbours Countries and the commercial metropolis of along the Zwin. His research is landscape- Bruges, especially its urban network. archaeological in scope, and integrates Address: Department of History, Henri multiple non-invasive prospection techni- Pirenne Institute for Medieval Studies, ques with historical, cartographical, and Ghent University. St-Pietersnieuwstraat 35, geological data. 9000 Gent, Belgium. [email: jan.dumolyn@ ugent.be] Address: Department of Archaeology, Henri Pirenne Institute for Medieval Studies, Ghent University, St- Ward Leloup is a historian and works as a Pietersnieuwstraat 35, 9000 Gent, doctoral researcher and teaching assistant Belgium. [email: [email protected]]

La Hanse et le ballast : les pierres erratiques dans le paysage portuaire de Bruges au Bas Moyen Age

La découverte d’un groupe remarquable de pierres arrondies, vivement colorées et d’une provenance géologique exotique dans les monuments et les champs des anciens avant-ports brugeois du Bas Moyen Age est à l’origine d’une étude multidisciplinaire portant sur leur fonction, leur provenance et leur importance économique. L’étude géologique a démontré qu’il s’agit de pierres de ballast de nature litholo- gique très variée et de provenance géologique lointaine. Une grande partie de l’assemblage est constituée de blocs erratiques arrondis qui ont été ramassés sur les plages à galets de la mer Baltique. Un autre groupe de roches indiquerait la côte nord-est de l’Angleterre comme source d’approvisionnement addi- tionnel. En vue de la présence fréquente de ces pierres à Hoeke, une attention plus particulière a été portée aux liens économiques entre Bruges et la Hanse, et au site portuaire hanséatique de Hoeke, auquel appartenait le droit d’entreposage de morue séchée ainsi que différentes autres activités

hanséatiques. L’article présent contribue également à la discussion portant sur les pierres de ballast comme catégorie d’objets archéologiques importants, en particulier dans un contexte méthodologique plus large, incorporant des études archéologiques, géologiques et historiques. Translation by the authors

Mots-clés: ballast, Hanse allemande, Bruges, blocs erratiques de la Baltique, commerce maritime

Die Hanse mit Ballast beladen: Findlinge aus Balto-Skandinavien in der spätmittelalterlichen Hafenlandschaft von Brügge

Der Fund einer bemerkenswerten Gruppe von lebhaft farbigen, gerundeten und geologisch exotischen Natursteinen in den Feldern und in den Denkmälern der spätmittelalterlichen äußeren Hafenanlagen von Brügge hat neue multidisziplinäre Forschungen bezüglich ihrer Funktion, ihrer Herkunft und ihrer besonderen wirtschaftlichen Bedeutung stimuliert. Geologische Untersuchungen haben gezeigt, dass die Steine als Grundgebirge Ballaststeine unterschiedlicher lithologischer Art und entfernter geologischer Herkunft angesehen werden können. Ein wesentlicher Teil ist durch erratische Gesteine konstituiert, die entlang der Baltoscandische Küste gesammelt wurden. Eine andere Gruppe kann bis zu den nordöstlichen Küsten Britanniens zurückverfolgt werden. Aufgrund der Gruppierung der Steinen, konnte eines besondere wirtschaftliche Verbindung zwischen Brügge und der Hanse und der hansea- tischen Siedlung von Hoeke, welche das Stapelrecht für Stockfisch und andere hanseatische Aktivitäten hatte, konstatiert werden. Der Beitrag erweitert die Diskussion zu den Ballaststeinen als eine wichtige archäologische Objektkategorie, im Besonderen, wenn diese in einem breiteren methodischen Kontext, unter Berücksichtigung archäologischer, geologischer und historischer Forschungen, studiert werden. Translation by J. Brettschneider

Stichworte: Ballaststeine, deutsche Hanse, Brügge, Baltoscandische Findlinge, Seehandel