Evolution of the lower Guadalquivir river floodplain during the middle-late Holocene. Geoarchaeology and palaeogeographic reconstruction of the Italica Roman site (SW Spain)

Abstract

Even before Italica was founded by the Romans at the end of the third century BC, this settlement maintained a close relationship with the morpho-dynamic evolution of the lower Guadalquivir river (SW Andalusia, Spain), especially with the lateral channel displacements. In order to reconstruct the palaeogeographic evolution of the alluvial area of Itálica during the second half of the Holocene, our research has focused on the study of the fluvial paleoforms and the alluvial soil-sedimentary sequence, with special emphasis on the analysis of the geoarchaeological records. Ancient maps and aerial photographs of various scales and diverse dates have been interpreted. Borehole cores and profiles, manually or mechanically opened, have also been done to obtain samples for laboratory tests of the representative floodplain soils and sediments. The chronologies provided by the archaeological record were completed with several radiocarbon dates. From these results we propose a possible solution at a local level to the traditional discussion about the existence and location of the ancient harbour of Italica; and for the alluvial plain as a whole, a double alternating palaeogeographic sequence trending to millennial-submillennial scale has been reached. The first one occurring controlled by hydrologic and climatic factors, modulated by a prolonged and extended human pressure on the basin, and showing a succession of four main stages characterized by the predominance of alluvial filling (4833-3206 cal BP; 3130-1989 cal BP; 1620 cal BP-XI century AD; and around the last 500 years), which are separated by periods of stability that favored alluvial soils formation; meanwhile, the second sequence presents short-time terms prone to riverbed design shifting (period prior to Late Bronze; Roman-republican era; central Middle Age), also separated by lengthy phases of morpho-hydrographic stability. In the latter case the main factor does not seem to be, as in the first of those, hydro-climatic shifts and land use changes, but rather the last small regional fluctuations of sea level that came with the second part of the Holocene.

Análisis de los procesos de territorialización en el bajo Guadalquivir a través de la cartografía histórica

“…Their hypotheses regarding the formation of different national territories are grounded on the analysis of the bibliographical sources and of the historical maps and plans 2. The analysis is applied to different case studies, such as the territory of Castilla y León (Chías and Abad 2008), the bay of Cádiz , the areas surrounding the bridge of Alcántara or the Monastery of El Escorial . Thus, its adaptability to different fields (architectural, urban and territorial) has been demonstrated.…”

“…En este sentido, el referente más próximo del panorama nacional lo constituye la producción científica de Chías y Abad, que apoyan sus hipótesis sobre la construcción de distintos territorios en el análisis de las fuentes bibliográficas, los mapas y planos históricos 2. El análisis se aplica a distintos casos de estudio, como por ejemplo al territorio de Castilla y León (Chías y Abad 2008), a la bahía de Cádiz , al entorno del Puente de Alcántara (Chías y Abad 2012) o al del Monasterio de San Lorenzo del Escorial , demostrando su adaptabilidad a distintas escalas (arquitectónica, urbana y territorial). Este tipo de análisis, que se engloba dentro del campo de la investigación documental, constituye, en nuestro caso, una parte de un método más amplio para diseñar itinerarios culturales.…”

El contraste micropaleontológico de la Historia: el Lacus Ligustinus romano

“…Hace unos 6.500 años, este estuario fue invadido por el mar durante el máximo transgresivo flandriense, conformando una amplia bahía que llegaba hasta Sevilla (Borja Barrera et al, 2018). Entre los 6.500 y 2.300 años BP, se produjo un importante proceso de colmatación debida en gran medida a los aportes fluviales, con la creación de nuevas marismas drenadas por numerosos canales mareales y parcialmente protegidas por una flecha de Doñana en continuo crecimiento hacia el sureste ( Fig.…”

“…Ruiz et al, 2006;Cearreta et al, 2007;Coccioni et al, 2009;Calvo-Marcilese & Langer, 2010;Alday et al, 2013). Esta reconstrucción paleogeográfica coincide con los textos históricos y con la inferida en otros estudios pluridisciplinares (Ruiz et al, 2010;Borja Barrera, 2013;Borja Barrera et al, 2018).…”

The LiguSTAR Project: Archaeological Survey Techniques as Applied to the Study of Roman Settlement on the Riverbanks of the Lacus Ligustinus (Southwest Spain)

“…Some of the main locations became Roman cities, such as Nabrissa (Lebrija), Asta (indigenous place name, Mesas de Asta, Jerez de la Frontera), Ebora (Cortijo de Évora, Sanlúcar de Barrameda) and (Montes et al 1998) morph-topographic restitution from Ménanteau (1982); and chronologies come from the references. By Borja et al (2018) with the author's permission.…”