GPR survey in the Punic harbour of La Martela (El Puerto de Santa Maria, Spain) and the methodology used for the processing and archaeological visualisation of the data (original) (raw)

2021, Non-Intrusive methodologies for large area urban research Rome Transformed conference

The first example of city planning in Western Europe is located in Cádiz (Spain) where the Phoenician colony of Gadir was founded. The city was interested in a long urbanisation process until Roman times. Several historical settlements, with industrial and commercial function, integrated the territory of Cádiz bay, as well as other life and burial places like the inland settlement of Castillo de Doña Blanca. This population process was adapted to the marine landscape of the Bay, while itself caused the urban transformation of the coastal environment of the medieval Cádiz Bay. Since 2016 our research team has carried out a non-invasive study with the aim of safeguarding the historic environment and advancing the research on the urban development. In this paper we show the results of the GPR surveys conducted in La Martela, the Punic harbour of Castillo de Doña Blanca. This is a Phoenician settlement known thanks to excavations carried out between 1979 and 2001 and the non-invasive investigations conducted by our team, consisting of aerial and land photogrammetry and geophysics surveys (with single and multi-antenna GPR system). La Martela is located on the floodplain, at the foot of the Phoenician settlement of Castillo de Doña Blanca, in a zone where there were no archaeological remains. A 6 hectares survey area was covered with the GPR multichannel Stream X system, thus leading to the discovery of an archaeological site of short-term phase. The orthogonal layout and the building types, with the elongated rooms of the Phoenician and Punic 'warehouse' type, are a clue to date its last construction phase to the 3rd century BC. In this communication we present the proposed workflow for optimising the results of large area multi-channel GPR surveys to obtain accurate urban cartography, enhancing the value of this method as a research source. Although geophysical techniques use interpolation as a mechanism to visualise data, these results provide enough quality to map underground structures of archaeological interest with precision. Ultimately, the floor plans obtained through geophysical techniques should be considered as valid as the ones derived from a traditional survey of excavated archaeological remains.