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Amazonia covers nearly 50% of Brazil. The history of this biome is marked by many changes in the landscape caused mainly by the Central and Northern Andes uplift. This event has influenced the palaeogeography of the Amazon and therefore its biogeography and possibly biodiversity. Herein we present palynological and lithostratigraphical results from the Solimões Formation in the well 1AS-33-AM. It was drilled in the Solimões Basin, Amazonas State, Brazil, reaching 405 m in depth. We identified 152 palynomorphs, in 32 samples, among them some biostratigraphical markers, such asCrassoretitriletes vanraadshoovenii,Fenestrites spinosus,Cichoreacidites longispinosus,Ladakhipollenites?caribbiensisandEchitricolporites mcneillyi, allowing us to recognise four biozonessensuLorente (1986):CrassoretitriletesInterval Zone (399.10–276.70 m), Asteraceae Interval Zone (276.70–262.00 m),Psilatricolporites caribbiensisInterval Subzone (239.90–70.00 m) andEchitricolporites–AlnipollenitesInterval Subzone (70–32 m). The palynological and lithostratigraphical results indicate two environmental phases. The palynomorph association presents a change marked by the sudden appearance and predominance ofGrimsdalea magnaclavatafrom 239.90 m upwards and a general increase in the number of species. The lithostratigraphy shows from approximately the same depth greater amounts of sandstones towards the top of the well, suggesting a change from a paralic to a fluvial environment of higher energy. The first phase can be associated with the Pebas/Acre depositional systems, wetlands composed by lakes and swamps with seasonal floods that existed from 23 to 7–5 Ma. The second phase indicates a fluvial system that may be interpreted as a record of the modern Amazon transcontinental fluvial system, which was already established in the Pliocene. [ABSTRACT FROM AUTHOR]