ABSTRACT
In recent centuries many of the old quarters of the city of Cádiz have been paved with rocks boulders of very different petrographic natures. The popular tradition supposes an imported origin to these materials, indicating that they were part of the ballast of the Spanish galleons that came from America. In recent years we have been carrying out two types of actions on these heritage materials, on the one hand: an archaeometric study based on the petrological, mineralogical and geochemical analysis of many of these rocks, trying to determine their petrographic, paleontological, textural, etc. features, that will allow to elaborate hypotheses about their possible areas of origin. On the other hand: an historical study based on the different archives of the city or other archives in the region, to obtain information about the maritime traffic to and from the city of Cádiz urbanism and its bay, over the last five centuries, as well as the use of these materials in the paving of the city and its houses.
Besides the study of the pavements of the old town of Cádiz, which are also present in other cities of the Bay, such as San Fernando or Chiclana de la Frontera, accumulations of anthropic origin (saburra), are being sampled at different points of the Bay of Cádiz, where boats throw ballast throughout history.
The data obtained is being compared with the analysis of geological samples from our litoteca, from different outcrops of the Gibraltar Strait region and the SW of the peninsula, as well as from the Atlantic coasts of western Europe, northern Africa, the Canary Islands and we pretend in the near future, of the American continent. Special attention will be given to those ports or areas of provisioning of ships in this historical period between the fifteenth and nineteenth centuries.
Some of the rocks studied seem to have a local-regional origin, but a great majority of them undoubtedly have an exotic origin to this geographical area, so they would come from the ballast transported by the different ships that made commercial routes, especially along the Atlantic Ocean, or from warships or ships that participated in the different attacks and invasions of the city.
