Ruben Martins

Development of a Tourist Route around the Mining Heritage of the Estremoz Anticline

The areas of the counties of Estremoz, Borba and Vila Viçosa, traditionally and since ancient times, have been a major region for extraction of marbles for use as a dimension stone in Portugal. The geological evolution of the Iberian Peninsula allowed the formation, in Alto Alentejo, of one of the World’s most important and famous marble deposits. The Estremoz Anticline, about 42 km long and 8 km in maximum width, is an impressive place where the strength and ingenuity of Man has been used for decades to turn the “land upside down”. The 27 km2 where the marble is concentrated is a place with a high density of quarries that have an unavoidable environmental impact, leaving stone exposed or accumulated in large tips, side-by-side with the Alentejo plains of wheat fields and olive trees. It is impossible to fully rehabilitate this area either for economic or strategic reasons, but it can be considered as resource for the promotion and development of industrial and scientific tourism and artistic and cultural events. A survey of the assets of the region has been undertaken and a wide variety of organizations and the industry are collaborating in planning a route and activities for the region.

Global Heritage Stone: Estremoz Marbles, Portugal

Abstract Paleozoic calcitic marbles are found in the Estremoz Anticline, Ossa-Morena Zone (Southern Branch of the European Variscides in Portugal). This 40 km NW–SE structure presents outcrop continuity and intense mining activity since the Roman Period. The structure has a Precambrian core and the younger rocks are from the Devonian Period. The marbles occupy an intermediate stratigraphic position in the Cambrian age Volcano Sedimentary Sequence. The Variscan Orogeny had two pulses with different intensities under ductile and brittle tension fields. The Alpine Cycle also caused more fracturing of the marbles. The geological features imprinted in the marbles are beautiful aesthetic patterns highlighted when used as dimension stone. Since the Roman period, pieces of art made with Estremoz Marble were exported abroad and can be found in museums and archaeological sites throughout Europe and North Africa countries. Present day, Estremoz Marble objects can be found all over the world. The very rich marble based heritage is omnipresent in cities, and the countryside is marked by intense mining activity side by side with rural industries; therefore the region has unique characteristics allowing the development of integrated industrial tourism routes, promoting sustainable development of industrial, scientific and technological cultural opportunities. The historical and widespread application of these marbles in national and international monuments, some of them already part of the UNESCO World Heritage Sites, is a condition to propose them as Global Heritage Stone Resource for their international recognition.

Application in Pottery of the Residual Soils Associated to Marbles from the Estremoz Anticlinal Region

Terra rossa is a residual soil that is derived from the chemical dissolution of carbonate rocks. This type of soil occurs in the region of the so-called Estremoz anticlinal, being the result of the weathering of extensive marble occurrences which are exploited for ornamental stone. The research work performed and disclosed in the present paper shows that terra rossa possesses appropriate compositional and technological properties for its use on ceramic applications, particularly for the local traditional pottery. In potential marble quarry sites several thick soil horizons can be found, and whenever the soil is removed marble is shown up. As a rule, the removed soil is deposited around the quarry, and so far no use has been given to it. Pottery has a long tradition in the Alentejo region, and Vila de Redondo and Aldeia de S. Pedro do Corval are known as emblematic centers of this activity. However, time has shown that the scarcity of high quality clay deposits has become an important issue. Therefore, potters are buying clay from other regions of Portugal, in particular in the area of Caldas da Rainha, located in the central west of the country and far from Alentejo, or even importing it from Spain. The cooperative research work carried out in the Laboratories of DGUE, the Department of Geosciences at the University of Aveiro (DGUA) and CENCAL, and at the pottery owned by the artisan Mestre Xico Tarefa, in Vila de Redondo, has shown that terra rossa, due to its physicochemical, mineralogical and technological properties, can be used as a raw material in ceramic manufacturing, particularly in the traditional pottery produced both in Redondo and S. Pedro de Corval.