Granite and Rock Crystal Quarrying in the Civitas Ammaiensis (North-Eastern Alentejo, Portugal): a Geoarchaeological Case Study
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1980-09_Babesch_12 24-08-2009 11:37 Pagina 171 BABESCH 84 (2009), 171-182. doi: 10.2143/BAB.84.0.2041643. Granite and rock crystal quarrying in the Civitas Ammaiensis (north-eastern Alentejo, Portugal): a geoarchaeological case study Devi Taelman, Sarah Deprez, Frank Vermeulen, Morgan De Dapper Abstract This paper presents the results of a geoarchaeological research project in the north-eastern Alentejo region of Portugal. The study focused on the granite and rock crystal exploitation in the territory of the Roman town of Ammaia. By means of non-destructive survey methods, performed by an interdisciplinary team of archaeologists, geomorphologists and geologists, the main quarries in the Civitas Ammaiensis were identified and investigated. The survey project aimed at gaining a clearer insight in the extractive industries of the town and, on a higher level, at gaining a better understanding of the economic and spatial organization of the town and its hinterland. INTRODUCTION component of the study. The main focus will be defining the relationship between town and coun- Until recently little scientific attention has been tryside. More specific: what conditions determined given to Roman stone exploitation in Portugal. the location of the town, how was the countryside This is surprising considering that the extraction used by the inhabitants in terms of economic of building stones is an essential part of the urban needs, etc. The case study on the stone extraction development of a specific region and, therefore, is a good example of this approach. of the urbanization process. It was not until the last decade of the 20th century that Portuguese archae- AMMAIA AND THE CIVITAS AMMAIENSIS ology engaged in the study of the provenance of Roman building material. Nonetheless, the archae- Location ologists mainly concentrated on localizing the quarries of the luxury stones that provisioned the The ruins of the Roman city are situated in the main urban centres.1 Research on quarries that territory of São Salvador da Aramenha, in the com- provisioned smaller provincial towns with local munity of Marvão (district of Portalegre, Alentejo, building stones is only seldom engaged. Portugal). The exact location has long-time been Since 2001 a multidisciplinary geoarchaeologi- the subject of discussion among academics. Until cal survey project of Ghent University is being the beginning of the 20th century archaeologists organized in the territory of the Roman town of and historians were convinced that the remnants Ammaia (north-eastern Alentejo, Portugal).2 One of Ammaia were located beneath modern Portalegre, of the aspects of the study comprises the stone circa 10 km in south-western direction, while the provisioning of the town and seeks to identify ruins in São Salvador da Aramenha were identi- and analyze the main Roman granite and rock fied as the ancient city of Medobriga. This assump- crystal quarries in its territory by means of non- tion was based on epigraphic finds in the Espírito destructive investigation methods. The research Santo church in Portalegre mentioning the Muni- is partly based on the results of archaeological ex- cipium Ammaiensis.5 It was not until 1935 that cavations, conducted in the city area since 1995,3 Leite de Vasconcelos refuted this hypothesis and and partly on survey activities organized in the proved the ruins in São Salvador da Aramenha as territory of the town.4 being those of Roman Ammaia.6 A second phase of the Ammaia survey project of The landscape surrounding the city is domi- Ghent University (started in 2008) will include a nated by the Serra de São Mamede, a mountain Site Catchment Analysis for the ancient Roman range of circa 40 km in length and with a maximum town. This part of the research builds on the geo- altitude of 1027 m (figs. 1, 2). The presence of this morphological and geological research of the first mountain range causes orogenetic rains in the phase and aims at elaborating the archaeological region, which results in an abundance of sources 171 1980-09_Babesch_12 24-08-2009 11:37 Pagina 172 Fig. 1. The Civitas Ammaiensis. (inset: Provincia Lusitania, frame: area depicted in figures 2 and 9; UTM-coordinates in metres) (after Mantas 2000). and streams, among which the Sever river. Com- that the only ancient literary reference to the Civi- bined with a fertile soil in the river valleys, these tas Ammaiensis is in connection with rock crystal,13 conditions provided satisfactory water and food it is certain that this mineral played an important provisioning in the immediate vicinity of the town.8 role in its economy.14 This is in striking contrast with most other parts of the Alentejo region that has, as a consequence of Historical background the drought and the dominance of hard rock near the surface, a low soil fertility.8 Ammaia was probably a newly founded Roman Ammaia was in Roman Imperial times the cap- town, without a pre-Roman precursor. The city site ital city of the Civitas Ammaiensis, an administrative does not correspond in any way to the character- entity that comprised a territory of approximately istic image of a protohistoric oppidum, which is gen- 60 x 60 km (fig. 1).9 It was part of the Provincia Lusi- erally located on a defensible hilltop with a good tania and was situated at the juncture of some of view on the surrounding land. Notwithstanding, the major Roman roads in the Iberian peninsula. several indications of a pre-Roman origin of the One of these roads linked Olisipo (modern Lisbon) town’s inhabitants have been encountered. The with Emerita Augusta (capital of the Provincia Lusita- members of the native Lusitanian tribe were in all nia, modern Mérida, Spain). The central location of probability forced by the Roman conquerors to the town in this road system entailed a high econo- abandon their settlements and move to a newly mic development of the city and its surroundings founded town, whose location met the Roman (fig. 2). In modern geographic terms, the civitas needs for administration and accessibility.15 stretches along both sides of the Portuguese-Spanish Since archaeological data for the earliest occu- border and abuts the river Tagus in the north. pation phase are absent, the exact time of the The main economic activities in the area were foundation is still unclear. The first inscriptions agriculture (e.g. wine, oil and cereals) and extrac- that mention the Civitas Ammaiensis date from the tive industries.10 Already in the Roman period, the period of emperor Claudius, from which can be territory was famous for its richness in minerals deduced that the town already existed at the end and stones. The foremost extracted stone was gran- of the first half of the 1st century AD.16 A second ite, to a lesser degree quartzite, schist and gneiss important source for dating the foundation is the were also present in the vicinity of the town.11 The Historia Naturalis by Pliny the Elder. In book IV mineral wealth comprises gold, silver, lead, the author enumerates the civitates of Lusitania in hematite and rock crystal.12 Judging from the fact the time of emperor Augustus. However, this list 172 1980-09_Babesch_12 24-08-2009 11:37 Pagina 173 Fig. 2. Geographical situation of Ammaia. 1. Granite quarry of Pitaranha, 2. Granite quarry of Santo António das Areias, 3. Granite quarry of Marvão, 4. Rock crystal quarry of Naves (frame: area depicted in figure 10; UTM-coordinates in metres) (map by Sarah Deprez). does not cite Ammaia, which could mean that the Civitas Ammaiensis played a transitional role town did not exist yet. A second possibility is that between the harbour of Olisipo and Emerita Pliny forgot to mention it, as was the case with Augusta.23 some other Roman civitates.17 If this last option is In the early years of the post-Roman period the valid, the establishment of the town was the result urban area remained relatively densely inhabited. of the territorial reorganization of the Iberian pen- During the Visigothic domination the town’s lay- insula by Augustus, an event that resulted in the out was even altered at several places (e.g. the foundation of numerous cities in Hispania and porta sul area and the Quinta do Deão area) in order Lusitania.18 to meet new urban standards.24 Contrary to the 4th Towards the end of the 1st century AD, in all and 5th-century prosperity, the archaeological data probability during the reign of emperor Vespasian, for the 6th century AD (e.g. imported ceramics are Ammaia received the status of municipium.19 This being replaced by local wares) indicate a clear de- event probably had no serious consequences for cline in the prosperity and the occupation. Gradu- the government of the town and its territory, but ally Ammaia depopulated and the inhabitants set- the urban centre developed a monumental core.20 tled in small villages in the hinterland of the In comparison to large parts of the Western Roman town.25 The causes for this decline are to Empire there are no indications of the region under- be found in the general political instability of the going a deep crisis in the Late Roman period. The period and the complete disappearance of the opposite is true: the town knew a certain economic Roman economic system. prosperity.21 Indications of this prosperity are the As early as the 9th century AD, during the Moor- large quantity of 4th-century coins, Late Roman ish domination, the town site was already largely Terra Sigillata and African Red Slip ware found reduced to ruins.26 The following centuries meant in different parts of its urban area.22 A study of the a further degradation of the town site, Roman con- villae in the hinterland produces the same results.