Construction of a highway in Northern Spain uncovered a large amount of plant fossils that were generally in a good state of conservation. In this paper, we specifically analysed 243 small fragments of charcoal and wood that were not totally carbonised, along with seven samples of pollen. We applied Mosbrugger and Utescher's [Palaeogeogr. Palaeoclimatol. Palaeoecol. 134 (1997) 61] "Coexistence Approach" to the results in order to calculate palaeoclimatic parameters. The presence of some extinct taxa (Taxodiaceae) enabled us to improve the dating from a previous geological study and to date the Caranceja fossil remains at the end of the Pliocene. In the Upper Pliocene, the old Saja Valley was covered by a very dense coniferous forest, with the presence of several angiosperms, with a more or less developed understorey of Ericaceae, depending on the period. This forest existed in temperate, fresh, and humid conditions, although it was subjected to a certain continentality that anticipated quaternary climatic oscillations. This represents one of the richest finds made to date in the Iberian Peninsula, with regard to quantity and diversity of materials, and is the most important one of fossil wood from the Iberian Neogene. (C) 2004 Elsevier B.V. All rights reserved.
