During the last glaciation, thick nival and periglacial sediments buried large sectors of the NW coast of Spain. The sediments were mostly eroded by the rising sea level during the Holocene, but in several places they remain, forming sedimentary cliffs. Radiocarbon dates obtained at the topmost layers of these cliffs prove that continental sedimentation was active until very recent times, followed by a retreat of the cliffs. During the first stages of the transgression, the erosion of the cliffs and the changes in the coastal system were controlled by the rising sea-level. Once the sea-level stabilized, the exhumation of inherited landforms, the supply of sediments, and a continuous continental sedimentation became the main factors. The last stages of cliff retreat were almost synchronous with the sedimentation of the upper layers of the deposits.

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The coast is very sensitive to variations in environmental conditions. The interaction of marine and continental processes causes a high dynamism, generating depositional formations with a high value for paleoenvironmental reconstruction. This work focused on the case of two edapho-sedimentary sequences located under the current beach, near of archaeological tumuli context at Areoso Island (Ría de Arousa, NW Iberia). With a geoarchaeological approach, sea level rise, environmental conditions and human occupation over 6000 years are interpreted. The results of granulometric and mineralogical data, elemental composition and stratigraphic features, help to identify three formation environments: granite weathering, continental (soil formation and erosion) and marine-aeolian. Geomorphological evolution from the last 6.0 kyr BP has been controlled by climate and sea level change and anthropogenic causes. The continental facies evidence low sea level up to 4.8 kyr BP. After 3.2 kyr BP, the formation of a beach-dune system was verified at an elevation similar to the present one. These results are coherent with others obtained in lagoons in the Galician coast. These edapho-sedimentary sequences located in an open coastal system will help to improve the Holocene sea level rise curve in the NW Iberia and to understand the context in which the most important archaeological structures on the island, the tumuli, began to be eroded.

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.

Areoso Island is located in the inner part of the Ría de Arousa, located on the Atlantic coast of northwestern Spain. With an area of 8 ha, it has a high density of Neolithic burial mounds. The island has a varied geomorphological heritage, highlighting the granite geoforms or the presence of edapho-sedimentary deposits. These coastal deposits are quaternary formations made up of unconsolidated material, which appear discontinuously throughout the Galician coastline. The analysis of its facies allows to detect past environmental changes, the study of which is of great interest in the field of Earth Sciences and of great use for other disciplines such as Archeology. the island has a high archaeological interest, highlighting the documented presence of five Neolithic funerary tumuli. At present, these constructions are threatened by marine erosion, derived from unique morphodynamic conditions. The deposits were sampled in different sectors and environments of the island, obtaining an almost continuous chronological sequence of the edapho-sedimentary formation during the last 6000 years. This allowed reconstructing the palaeoenvironmental evolution, differentiating several stages, where the Holocene transgression played a fundamental role in its formation. 6000 years ago, with a sea level lower than today, the emerged surface was much higher than in the present, and could even be connected to the continent. These facts are relevant to archaeological interpretation, as they suggest that the burial mounds were not built in a coastal setting. The study of the ancient deposits of Areoso allows obtaining different proxies (sedimentary, geochemical, biological, archaeological), which are of great help to interpret the archaeological context, since anthropic activities are reflected in the resulting deposits. The high scientific and didactic interest of the ancient edapho-sedimentary formations makes it necessary to put them in value. This palaeoenvironmental information means that they should be considered natural heritage. In the current context of rising sea levels, many of them are seriously threatened, so it is necessary to promote their management and geoconservation, to the extent that natural processes allow. The objective of this work is to value them and proclaim their importance as environmental records.