Several red paleosoils related to Tertiary deposits and showing a good development of calcic and argillic horizons are studied, According to their morphology and clay minerals a genetical change towards the top of the secuences has been identified. An iniatilly semiarid mediterranean climate giving raise to alfisols, would change into a more humid one, with a rainy warm season. Chemical paleoweathering index, as well as Fe and Ti contents, also confirm this trend towards an increase in weathering, The characteristic of the youngest soil allows us to correlate it with the oldest Pliocene Raña formations.