Geochemistry of Birch Creek, Inyo County, California a travertine depositing creek in an arid climate

A small stream in eastern California was studied in detail to determine the causes of travertine deposition from the stream. Although the ground water feeding the stream is slightly supersaturated to just saturated with calcite, the ground water is supersaturated with CO₂ with respect to the overlying air. The water becomes increasingly supersaturated with calcite in a downstream direction as CO₂ loss to the air and by photosynthesis exceeds the rate of precipitation of calcite. Water loss by evaporation was below detection and does not play an important role in calcite deposition in this case. The water loss is by seepage through the stream bed. Observations showed variations in HCO⁻₃, pH, discharge, Ca⁺², relative humidity, water and air temperatures, and dissolved CO₂. Comparisons of observed and equilibrium states are given for five sampling stations along the stream.