Description:
<jats:title>Abstract</jats:title><jats:p>We evaluate the efficacy of the stable isotope composition of precipitation and plant waxes as proxies for paleoaltimetry and paleohydrology in the northern tropical Andes. We report monthly hydrogen (δ<jats:sup>2</jats:sup>H<jats:sub>p</jats:sub>) and oxygen (δ<jats:sup>18</jats:sup>O<jats:sub>p</jats:sub>) isotope values of precipitation for an annual cycle, and hydrogen isotope values of plant waxes (δ<jats:sup>2</jats:sup>H<jats:sub>wax</jats:sub>) obtained from modern soils along the eastern and western flanks of the Eastern Cordillera of Colombia. δ<jats:sup>2</jats:sup>H<jats:sub>p</jats:sub>, δ<jats:sup>18</jats:sup>O<jats:sub>p</jats:sub>, as well as the unweighted mean δ<jats:sup>2</jats:sup>H<jats:sub>wax</jats:sub> values of <jats:italic>n</jats:italic>‐C<jats:sub>29</jats:sub>, <jats:italic>n</jats:italic>‐C<jats:sub>31</jats:sub>, and <jats:italic>n</jats:italic>‐C<jats:sub>33</jats:sub> <jats:italic>n</jats:italic>‐alkanes in the eastern flank show a dependence on elevation (<jats:italic>R</jats:italic><jats:sup>2</jats:sup> = 0.90, 0.82, and 0.65, respectively). In stark contrast, the stable isotope compositions of neither precipitation nor plant waxes from the western flank correlate with elevation (<jats:italic>R</jats:italic><jats:sup>2</jats:sup> < 0.23), on top of a negligible (<jats:italic>p</jats:italic>‐value >0.05) correlation between δ<jats:sup>2</jats:sup>H<jats:sub>wax</jats:sub> and δ<jats:sup>2</jats:sup>H<jats:sub>p</jats:sub>. In general, δ<jats:sup>2</jats:sup>H<jats:sub>wax</jats:sub> values along the eastern flank of the Eastern Cordillera seem to follow the trend of a simple Rayleigh distillation process that is consistent with studies elsewhere on the eastern side of the Andes in South America. Neither δ<jats:sup>2</jats:sup>H<jats:sub>p</jats:sub> nor δ<jats:sup>18</jats:sup>O<jats:sub>p</jats:sub>, and therefore δ<jats:sup>2</jats:sup>H<jats:sub>wax</jats:sub>, offer reliable estimates of past elevations in the western flank, due perhaps to water vapor source mixing, evaporation overprint, contrasting plant communities, and/or differences in evapotranspiration. Thus, δ<jats:sup>2</jats:sup>H<jats:sub>wax</jats:sub> is only reliable for paleohydrology and paleoaltimetry reconstructions on the eastern flank of the Andes, whereas interpretations based on δ<jats:sup>2</jats:sup>H<jats:sub>p</jats:sub> and/or δ<jats:sup>18</jats:sup>O<jats:sub>p</jats:sub> west of the highest point of the Eastern Cordillera need to consider mixing of moisture sources in addition to precipitation amount.</jats:p>