The study of the Holocene sediments from AÑ1, AÑ2 and DV1 cores, drilled between Añavieja and Dévanos (Soria), has allowed to define nine sedimentary facies: black and grey lutites, brown lutites with carbonate nodules, phytoherms, yellow sands, 'yellow sands with tufa debris, yellow silts, black lutites with macrophyte remains and tufa debris, and gravels. These facies permit to interpret the Holocene as a fluvio-lacustrine area integrated by a shallow lake that passed downwards into a fluvial system with a high tufa development. The fluvial system corresponds to the barrage fluviatile model. Eleven new radiometric datings (14C and U/Th) allow to establish a precise correlation between cores and evidence noticeable changes in thickness for the Holocene series, from 6 m-thick in the lake to more that 20 m-thick in the pools between tufa barrier
