Las terrazas fluviales cuaternarias del río Ebro en el alto Ebro (Incinillas-Conchas de Haro)

Abstract

Geomorphological, sedimentological and chronological techniques have been applied to identify and characterize the Quaternary fluvial evolution of the Ebro River in the eastern upper Ebro basin. This investigation identified a sequence of 11 fluvial terraces (T1-T11 from highest to lowest).The highest remnants (up to +140 m above current river level) date back to the Early Pleistocene and the lowest to the Holocene. The fluvial sediments of all terraces except T11 are comprised of well-sorted coarse particles deposited in gravel bars or channels. In contrast, T11 is made up of massive silty sands. Alluvium composed of coarse particles was deposited during cold and dry periods of the Quaternary when sediment delivery to valley bottoms was high. T11 was formed under warmer and wetter conditions, when forest stabilized hillslopes, reducing sediment availability. Thus the fluvial sequence was created in response to the combined action of Quaternary climatic oscillations and uplift.