Quaternary evolution of the Vera
and eastern Sorbas basin
Morphological, sedimentological and pedological studies of river terraces, slope deposits and travertines contribute to the geomorphologic interpretation of a basin and allow the reconstruction of its landscape and paleoclimatic evolution. The aim of this Project is to gain a better understanding of Pleistocene and Holocene geomorphic and pedologic development in the Vera and eastern Sorbas basin, one of the driest regions in Europe.
The alternation of accumulation and erosion processes of a river system generated a staircase of terraces, alluvial fans, pediments, glacis, etc. These landforms are the result of the complex interplay of Quaternary climate fluctuations, tectonics, river capture, eustatic oscillations etc. Regarding radiometric dating, sedimentological and palynological analysis of travertine deposits are helpful in establishing a chronological framework of a morpho- and pedostratigraphy, as well as a paleoenvironmental reconstruction of a basin.
Sequence of Quaternary fluvial terraces near Antas
The fluvial terrace sequence of the Aguas and Antas valley is likely to reflect marked changes in flood and sediment supply regimes, and in particular rare high-magnitude events, associated with long-term global climate changes. In the Rio Aguas it has also been possible to differentiate between Pleistocene fluvial terraces associated with braided channel platforms, deposited during cold stage climates (stages 6 and 2), and terraces deposited by meandering channels during interglacial periods (e.g. the Holocene). Braided and torrential river structures in gravel reflect violent fluvial dynamics and increased sediment discharge. These dynamics probably occur as a result of precipitation concentration and less vegetation cover which produce an increase in the overland flow.
Clay coatings of an early Pleistocene palaeosol
Travertine deposits in the Vera basin provide paleoclimatic data. The principal periods of travertine formation which represents more humid climate conditions, fall within 88,000 +/- 4000 – 94,000 +/- 5000 yr B.P. (stage 5a) and 64,000 +/- 2000 – 54,000 +/- 2000 yr B.P. (beginning of stage 3), and were drastically reduced during stage 2 and the Holocene.
A Quaternary soil chronosequence of the Aguas river terrace has been established, and it seems to be typical for the Vera basin. The chronology of the fluvial sequence of 15 geomorphological units was determined. The data indicate that Rhodoxeralfs (Red Mediterranean soils) formed during early Pleistocene, Haploxeralfs (reddish Mediterranean soils) from the middle Pleistocene to isotopic stage 5, and weak developed soils (e.g. Haploxerolls) during late Pleistocene and Holocene. The youngest Haploxeralfs are associated with the fluvial terrace T3 overlaid by travertine deposits dated at 148,000 +/- 8000 yr B.P. (U/Th), and on the last interglacial marine terrace located at +9 m a.s.l.
In the context of a geoarchaeological survey of the Vera basin geomorphological studies have been carried out in the Aguas and Antas valley. The deposition of up to four fluvial terraces during isotope stage 2 point to important erosion and accumulation processes at the end of Late Pleistocene in the Vera basin. In contrast to the stage 2 and 6 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 climate changes of the LIA are recorded in Sierra Nevada by glacier fluctuations as 210Pb dating and historical data indicate. The reconstruction of the evolution of the Aguas and Antas valleys stress that the aggradation 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. [Poster]
Holocene alluvial deposits of the lower Aguas river
Title: Quaternary evolution of the Vera and eastern
Sorbas basin (south-east Iberian Peninsula).
Title: AGUAS Project. Paleoclimatic
reconstruction and the dynamics of human settlement and land-use in
the area of the middle Aguas (Almería), in the south-east of
the Iberian Peninsula.
SCHULTE, L.; (2003) River-response and terrace aggradation in the Mediterranean Iberian Peninsula during historical times. In: Thornsdaycraft,
V. R.; Benito, G.; Barriendos, M. & Llasat, M. C. (eds.): Palaeofloods,
Historical Data & Climate Variability. Applications in Flood Risk
Assessment. Proceedings of the PHEFRA International Workshop held
in Barcelona, 16th-19th October, 2002 (67-72). CSIC–Centro de
Ciencias Medioambientales - European Comisión, Programme on Environment
and Sustainable Development, Madrid. ISBN-84-921958-2-7.
SCHULTE, L. (2002): Climatic and human influence on river systems and glacier fluctuations in southeast Spain. Quaternary International. 93-94: 85-100. Pergamon – Elsevier, New York.
SCHULTE, L. (2002): Evolución cuaternaria de la depresión de Vera y de Sorbas oriental (SE-Península Ibérica). Reconstrucción de las fluctuaciones paleoclimáticas a partir de estudios morfológicos y edafológicos. 251 pp. Servei de Publicacions de la Universitat de Barcelona. Barcelona. [Extended abstract in English: Quaternary evolution of the Vera basin (SE-Iberian Peninsula). A reconstruction of paleoclimatic fluctuations from morphological and pedological studies.]
SCHULTE, L. (2002): The influence
of climate change and human dynamics on fluvial environments in southeastern
and northeastern Spain over the last 1500 years. IN: International
Conference on Environmental Dynamics and History in Mediterranean areas.
International Association of Geomorphologist (IAG), 79. Université
de Paris-Sorbonne, France, 24-26/4/2002. Paris.
SCHULTE, L. & JULIĄ, R. (2001): A Quaternary soil of Southeastern Spain. Zeitschrift für Geomorphologie. N.F., 45 (2): 145-158. Berlin-Stuttgart.
CASTRO, R. V.; R. W. CHAPMAN, L.; DEVER, T.; ESCORIZA, C. A.; FRENCH, S.; GILI, W.; HERGET, J. L.; LÓPEZ, V.; LULL, J.; Mc GLADE, R.; MICÓ, D.; PASSMORE, C.; RIHUETE, R.; RISCH, M.; SANAHULA, E.; SCHULTE L.; STEVENSON, A. J. & VERHAGEN, P. (2000): Natural and social dynamics in the Río Aguas (Almería, Spain) from the middle Holocene to modern times. In: P. Balabanis, D. Peter, A. Ghazi & M. Tsogas: Proceedings of International Conference on Mediterranean Desertification, Crete 1996. Research Results and Policy Implications, vol. 2, 21-31. European Comission
SCHULTE, L. & JULIÀ, R. (1999): Quaternary soil development on river terraces in the Vera basin. En: J. Bech (Ed.): 6th International Meeting on Soils with Mediterranean Type of Climate (583-585). Barcelona.
FRENCH, C. & SCHULTE, L. (1998): Las Pilas section. In: P. V. Castro, R. W. Chapman, S. Gili, V. Lull, R. Micó, C. Rihuete, R. Risch & M. E. Sanahuja Yll (Hrsg.): Aguas Project. Paleoclimatic reconstruction and the dynamics of human settlement and land-use in the area of the middle Aguas (Almería), in the south-east of the Iberian Peninsula (49-52). European Comission. Directorate-General, Science, Research and Development; Brussels
SCHULTE, L. (1998): Geomorphological Map: river terraces of the lower Aguas Valley. In: CASTRO, P. V.; CHAPMAN, R. W.; GILI, S.; LULL, V.; MICÓ, R.; RIHUETE, C.; RISCH, R. & SANAHUJA Yll, Mª E. (Eds.): Aguas Project. Paleoclimatic reconstruction and the dynamics of human settlement and land-use in the area of the middle Aguas (Almería), in the south-east of the Iberian Península (46). European Comission. Directorate-General, Science, Research and Development. Luxembourg.
SCHULTE, L. (1998): Quaternary morphodynamic and climate changes in the middle and lower Aguas Valley. In: CASTRO, P. V.; CHAPMAN, R. W.; GILI, S.; LULL, V.; MICÓ, R.; RIHUETE, C.; RISCH, R. & SANAHUJA Yll, Mª E. (Eds.): Aguas Project. Paleoclimatic reconstruction and the dynamics of human settlement and land-use in the area of the middle Aguas (Almería), in the south-east of the Iberian Península (38-42). European Comission. Directorate-General, Science, Research and Development. Luxembourg.
SCHULTE, L. (1998): Respuesta de la dinámica fluvial a los cambios climáticos en el sureste peninsular. En: GÓMEZ, A. & SALVADOR, F. (Eds.): Investigaciones recientes de la Geomorfolgía Española. Aportaciones a la V Reunión Nacional de Geomorphología (Granada, 1998) (433-443). Logroño.
SCHULTE, L. (1997): Aportación a la reconstrucción plaeoambiental del sureste de la Península Ibérica. En: Cuaternario del litoral y entorno continental del mar Alborán, AEQUA, 44-46 pp. Sevilla.
SCHULTE, L. (1996): Aportación a la evolución paleoambiental del Sureste de la Península Ibérica: Cambios morfodinámicos, edafológicos y climáticos en la Cuenca de Vera durante el Pleistoceno y Holoceno. En: Notes de geografia física, 25 (99-127). Barcelona.
SCHULTE, L. (1996): Morfogénesis cuaternaria en el curso inferior del Río de Aguas (Cuenca de Vera. Provincia de Almería). Cad. Lab. Xeol. Laxe, 21: 223-236. La Coruña
SCHULTE, L. (1995): Jungquartäre Flussdynamik des Río Antas im zentralen Vera-Becken (SE-Spanien). Geoökodynamik, 16 (173-196). Bensheim.