A High-Resolution Record of Holocene Climate Change in Speleothem Calcite from Cold Water Cave, Northeast Iowa

High-precision uranium-thorium mass spectrometric chronology and 18 O- 13 C isotopic analysis of speleothem calcite from Cold Water Cave in northeast Iowa have been used to chart mid-Holocene climate change. Significant shifts in δ 18 O and δ 13 C isotopic values coincide with well-documented Holocene vegetation changes. Temperature estimates based on 18 O/ 16 O ratios suggest that the climate warmed rapidly by about 3δC at 5900 years before present and then cooled by 4δC at 3600 years before present. Initiation of a gradual increase in δ 13 C at 5900 years before present suggests that turnover of the forest soil biomass was slow and that equilibrium with prairie vegetation was not attained by 3600 years before present.