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Environmental fluctuations during the Holocene caused important landscape changes in the Central Ebro Basin, which is a very sensitive region due to its semiarid climate, lithology, and continuous human presence. Severe erosion processes hinder palaeoenvironmental and archaeological record preservation. Infills of ephemeral stream valleys in semiarid environments are some of the best contexts for geoarchaeological studies. In this paper, we analyse the geomorphological processes, pedological features, and charcoal and pollen content and composition of the sedimentary sequence of La Poza Valley catchment area, with the support of additional information from La Bajada Valley. 14 C dates for 13 charcoal fragments provide the necessary chronological control. We describe 5 sedimentary units and a polycyclic sequence of six soils that covers most of the Holocene, beginning ca. 9.5 ky cal BP. Buried soils help to identify stability periods in the sedimentary sequence, while incision stages are detected through erosive contacts and terraced organisation of the sedimentary units. Charcoal and pollen content and composition, as well as the soil development, reveal an open forest of junipers and pines for the Early Holocene in the lower part of the sequence (mainly in Unit 1), very different from the current deforested landscape, also represented in the sequence (Unit 4). Thus, La Poza record shows the environment was favourable for hunter-gatherers from the Late Mesolithic and for the first Neolithic farmers. From then on, progressive degradation due to a combination of climate changes and increasing human pressure led to the current deforested landscape. [ABSTRACT FROM AUTHOR]

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 Vinalopó 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. [Copyright &y& Elsevier]