Role of human actions on landscape changes since the Upper Holocene in the Bajo Segura Basin (SE Spain)

Abstract

Abstract The study area is the Bajo Segura Basin, located in the easternmost sector of the Betic Ranges. The existence of a wide coastal lagoon occupying the depressed spaces (at least since the Middle Pleistocene) has been inferred, in previous works, from the stratigraphic, micropaleontological and sedimentological analyses. Particularly during the Upper Holocene the environmental morphology was modified. This paper aims to correlate the geomorphological, sedimentological and micropaleontological data with archeological and geoarcheological information of the Upper Holocene. This will allow to hypothesize the recent environmental evolution and its relation to human settlement. The geomorphological approach consists in the analysis of six mechanical cores and geoarcheological studies in several sites. Archeological data is based on sites dating to the 2nd millennium B.C. (Bronze Age), 725–550 B.C., 8th–6th centuries B.C. (Early Iron Age), 550–206 B.C. (Iberian Age), 6th–3rd centuries B.C., 206–500 B.C. (Roman Age), 3rd century B.C.–5th century A.D. and 500–900 A.D., 5th–8th centuries A.D. (Early Middle Ages). During the Bronze Age, the Bajo Segura Basin was occupied by a coastal lagoon with marine communication. The fossil assemblage indicates a greater marine influence near the coast and fresher conditions further away from it. At least since the subsequent period, and especially since the Iron Age, an activation of the alluvial processes is recorded establishing paleogeographical changes in the lagoons. During the roman period the southern landscape (Segura River) is dominated by the flood plain with associated lagoons and freshwater marshes, at least in the inner part. To the north, the Vinalopo alluvial fan progrades and reduces the dimensions of the lagoonal areas. The swampy conditions remained until the Modern Age. Agricultural expansion reached its maximum development in the 18th century A.D. and gave rise to the present landscape.