THE UNESCO 14TH CENTURY FORTIFICATIONS OF CERCA NOVA (ÉVORA, PORTUGAL): PROVENIENCE AND CLASSIFICATION OF GEO-MATERIALS AND VASCULAR PLANTS INVENTORY

Abstract

The historic centre of Évora city (Portugal) is classified as UNESCO World Heritage Site since 1986. It is surrounded by fortifications built during the 14th century (Cerca Nova) and classified as National Monument since 1922. After their construction, at least five restoration interventions (15th, 16th, 17th, 18th and 19th centuries) were executed. In this research, a lithological characterization of the construction materials has been conducted. The classification of the different rocks observed at Cerca Nova give archaeometric information as proveniences and ancient extraction areas. Geological data suggests a supply of geomaterials mainly from local quarries and from scattered boulders in the countryside of the city. In extremely limited quantities, some lithologies such as marbles and limestones, not belonging to local outcrops, were used. These are most likely spoliations materials, whose act was widely used in the medieval period. In addition to the characterization of the lithological materials, the inventory of the vascular plants growing on the fortifications recognized 42 taxa belonging to 26 families and 34 genera. Half of the 42 taxa verified are represented by native plants and the other half are represented by exotic species. The latter includes nine alien invasive taxa, despite the individuals belonging to this group of species are limited to some portions of the masonry and represent a rather low percentage when referring the sample. The origin of the alien taxa is mainly from the tropical-American biogeographical region