Bartolomé Úcar Miguel 2017 B1 Cave is part of Las Fuentes de Escuain karstic system developed in Paleocene-Eocene limestone (internal ranges) in Central Pyrenees. This works shows the study of 425 meters small sub- horizontal gallery of develop and +9m/-2m of gradient. Geomorphological study allowed it recognizes chemical deposits (carbonate deposits) and clastic deposits (falling blocks and fluvial). Moreover, a stalagmite that covers a temporal period between 3601 y BP and 945 y BP has been studied. Mineralogical, textural and geochemical analyses show the presence of aragonite and calcite along the stalagmite. Textural and mineralogical observations point out that aragonite fibers coexisting with neoformic calcite. Age model stabilized with 8 U/Th ages shows changes in growth rate. Thus, aragonite formation took place between ~3500 y BP y 2750 y BP (Bronze-Iron ages transition). Aragonite presence, low growth rate and heavy d13C and d18O isotopic values point out low water availability during this period. These dates are coherent with regional and hemispheric reconstructions TAZ