EL REGISTRO DE LOS CAMBIOS DE CLIMA EN LA ESTRATIGRAFIA DE LA AMAZONíA COLOMBIANA I. NEOGENO - INICIOS DEL CUATERNARIO

stratigraphic units of the colombian amazon region are composed of the following geological formations: solim？es late miocene age (neogene period 23.03 to 2.6 ma miocene-pliocene), the formation jericó described herein and that was deposited between the pliocene and pleistocene, and the formation isa (i？á), which has been considered of pleistocene age. in the holocene is predominant sedimentary material directly related or not with the influence of the amazon river. although much of the sedimentary environments of the solim？es formation of tertiary age correspond to rivers and floodplain forest vegetation, lakes and marshes (pantanales) are also present. some of them have high concentration of salts in solution and sequences of hardened paleosoils that covers positive landforms formed in environments where some vegetation types are similar to the present types but with woodland savannas. the evidence suggests a warm climate with a prolonged dry season. the following stratigraphic unit, which is described herein jericó, lies in a discordant form on the solim？es formation and correspons to fluvial sediments that have been affected by the processes of generation of bauxites after his deposition. this action requires warm climates with a long rainy period, followed by a short dry season. the evidence of processes occurring in the two formations indicates that during the neogene, the amazon region (at least the colombian part) experienced a climate with a dry season, being very long during solim？es formation and short in jericó formation, but in both cases the climatic conditions were different to the actual climate. isa formation has a fluvial origin, with hilly topography that protrudes 2 or 3 meters above the terrace of leticia, and the nearby brazilian territory is not covered by the existing terrace. the detritus of the isa formation have been contributed by reworking of the jericó formation and were deposited under very humid condition, with higher rainfall amounts