Significance and Broader Impacts

October 29, 2022

Major John Wesley Powell first introduced the concept of the 100th Meridian as an aridity gradient in 1879 in a report to the United States Congress. In this statement, he described a transition from the moist southeastern climate to an arid western desert that occurred along this margin (Powell, 1879). Since then, climate change has driven this boundary to the east with temperature increase, and Seager et al. (2018) suggests that this will continue. Speleothem records in Central Texas have recorded similar warming events and their relationship with more polarized precipitation along the 100th Meridian (Miller et al, 2021). Until Miller’s recent study, speleothems seldom produced resolution on annual or seasonal timescales. However, after discovering the likely seasonal banding evident in CLFM imagery, we considered that water chemistry changes due to geologic processes could be the cause of these seasonal changes.  

Characterizing elemental concentrations in cave dripwater and associated farmed calcite in Central Texas should improve our understanding of soil moisture and effective precipitation in the region. By developing a method to evaluate TE/Ca ratios, this project seeks to evaluate the relative extent to which various epikarst and in-cave processes cause the seasonal banding observed in the speleothem record (Miller et al, 2021). Similar studies have proven that trace element analysis by Q-ICP-MS can produce data with excellent signal to noise ratios much more quickly and cost-effectively than alternative methods such as sector field ICP-MS, TIMS, and ICP-AES  (Owen et al., 2016;  Yu et al., 2006).