Sea-level change and human occupation over 6000 years on Areoso Island (Ría de Arousa, NW Iberian Peninsula)

Abstract

Coastal areas are extremely sensitive to variations in environmental conditions. The interaction of marine and continental processes causes a high degree of dynamism, generating depositional formations of great value for palaeoenvironmental reconstruction. This paper focuses on two pedostratigraphic deposits located under the current beach, in close proximity to archaeological tumuli located on Areoso Island (Ría de Arousa, NW Iberian Peninsula). Employing a geoarchaeological approach, sea-level rise, environmental conditions and human occupation over a 6000-year period are interpreted. The results of granulometric and mineralogical data, elemental composition and stratigraphic features, help to identify three successive environments: continental (rock weathering, soil formation and erosion); a transition to a coastal environment; and the establishment of full coastal conditions. The geomorphological evolution of the last 6.0 kyr BP has been controlled by climate, sea-level rise and human activity. The continental facies shows evidence of low sea-level up to 4.8 kyr BP and the first evidence of coastal processes after 3.2 kyr BP. These pedostratigraphic deposits located in an open coastal system improve the Holocene sea-level rise curve in the NW Iberian Peninsula and help to understand the context in which the most important archaeological structures on the island (the tumuli) began to be eroded.