The Aragón Valley glacier (Central Western Pyrenees) has been studied since the late nineteenth century and has become one of the best areas in the Pyrenees to study the occurrence of Pleistocene glaciations and the relationships between moraines and fluvial terraces. New morphological studies and absolute ages for moraines and fluvial terraces in the Aragón Valley allow a correlation with other Pyrenean glaciers and provide solid chronologies about the asynchroneity between global last glacial maximum (LGM) and the maximum ice extent (MIE). Six frontal arcs and three lateral morainic ridges were identified in the Villanúa basin terminal glacial complex. The main moraines (M1 and M2) correspond to two glacial stages (oxygen isotopic stages MIS 6 and MIS 4), dated at 171 Ϯ 22 ka and 68 Ϯ 7 ka, respectively. From a topographical point of view, moraine M1 appears to be linked to the 60 m fluvioglacial terrace, dated in a tributary of the Aragón River at 263 Ϯ 21 ka. The difference in age between M1 moraine and the 60 m fluvioglacial terrace suggests that the latter belongs to an earlier glacial stage (MIS 8). Moraine M2 was clearly linked to the fluvioglacial 20 m terrace. Other minor internal moraines were related to the 7-8 m terrace. The dates obtained for the last glacial cycle (20-18 ka) are similar to other chronologies for Mediterranean mountains, and confirm the occurrence of an early MIE in the Central Pyrenees that does not coincide with the global LGM.
La Virgen is an ephemeral tributary of the Ebro River in northeast Spain with a complex alluvial sequence. We analyzed alluvial stratigraphy to develop a model of Holocene fluvial evolution for La Virgen and infer causes of floodplain dynamics. Three alluvial terraces were mapped and described using a combination of geoarchaeological and geomorphological techniques. Stratigraphic ages were estimated using 14 C dating and archaeological remains. Sedimentation in the valley floor commenced in the Neolithic period ca. 6000 BC and continued during the Bronze and Iron ages (ca. 1800-500 BC), the Iberian and Roman periods (ca. 500 BC-AD 500), and the Middle Ages (ca. AD 500-1500). The main terrace (N3) is 14 m thick and predominantly composed of sand, silt, and clay that we believe are derived from local hillslopes and represent a long period of human-induced soil erosion that intensified during the Bronze and Iron ages until the Late Roman period.
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