Climatic and human influence on river systems and glacier fluctuations in southeast Spain since the Last Glacial Maximum

Abstract

The semi-desert environments of the Mediterranean region are most sensitive to climatic changes and human land exploitation. This paper is focused on the Late Pleistocene and Holocene geomorphic evolution of southeast Spain, one of the driest regions in Europe. Late Pleistocene and Holocene chronosequences of river terraces were established for the Antas and Aguas valleys, respectively. The deposition of up to four fluvial terraces during isotope stage 2 points to important erosion and accumulation processes at the end of Late Pleistocene in the Vera basin. In contrast to the stage 2 deposits, the Holocene terraces are composed of point bar deposits accumulated by meandering rivers with less sediment discharge. According to the obtained 14C-dating and extracted pottery fragments, Holocene terrace deposition occurred during the Atlantic period, early Middle Ages, Little Ice Age (LIA) and the 20th century. The most outstanding site in southern Spain for studying Holocene glacier shifts (up to five end-moraines) is the Veleta cirque in Sierra Nevada, where the southernmost glacier of Europe persisted during the Little Ice Age. The climate changes of the LIA probably are recorded by two glacier fluctuations, as indicated by 210Pb dating and historical data. The reconstruction of the evolution of the Aguas and Antas valleys stress that the aggradations of the lower terraces is mostly climate-induced although during the last 500 years, human interference in the landscape (Christian conquest, mining boom of the 19th century, etc.) may have played an important role to river dynamics.