Two Odd Ones Out: Mediterranean Ballast Stones and Italian Maritime Connections in the Medieval Bruges' Harbor System

Excavations in the Bruges' Medieval outer ports of Hoeke and Monnikerede, located along the Zwin tidal inlet, revealed numerous rounded cobbles of exotic geological provenance among which were two specimens of remarkable mineralogical composition. An interdisciplinary study combining archeological, geological, petrographic-geochemical, and historical research has demonstrated their Mediterranean, i.e., Italian, provenance. A first stone is identified as Carrara marble originating from the alluvial fans of the Apuan Alps, deposited along the Versilian coast near the Renaissance towns of Lucca, Pisa, and Genoa. The second cobble is determined as a bioclastic calcarenite limestone from the Apulian shores. Both finds are interpreted as part of the non-saleable ballast once put in the holds of Italian carracks and galleys that touched the Flemish ports during the late thirteenth to fifteenth centuries. As such, both seemingly ordinary objects constitute a rare material and lithological testimony of an important late Medieval commercial network between the Mediterranean and North Sea coasts. Furthermore, the very rare occurrence of these Mediterranean cobbles compared to thousands of Scando-Baltic and Anglo-Scottish ballast stones in the whole of the Bruges outer harbor area can be related to differences in maritime traffic frequency and sheer commercial volumes. Also, the nature of the ballast itself and the ballasting procedures are important, the whole making Mediterranean ballast stones considerably less detectable in the Bruges' harbors than their North-European equivalents.