A HIGH-RESOLUTION CLIMATE RECORD THROUGHOUT MIS 3-4 FROM CREVICE CAVE, MISSOURI, USA

A continuous, well-dated climate record derived from speleothems from Crevice Cave in southeastern Missouri is available from 110 ka to 25 ka, and captures a long series of events that can be interpreted as significant changes in temperature, precipitation, and vegetation. If δ¹⁸O can be soundly interpreted as a qualitative measure of temperature, then the “warmest” time of this entire period occurred around 72 ka, at a time of rapid global ice accumulation during MIS 4. The δ¹³C signal at this same time indicates heavy forest cover (δ¹³C ~ -9 per mil). A prominent switch to grassland signatures occurs after 70 ka and reaches peak values (δ¹³C ~ -2 per mil) around 57 ka. Another large transition occurs between 57 ka and 53 ka, with values again approaching -9 per mil at 53 ka. Superimposed on these large trends interpreted as vegetation changes are δ¹⁸O oscillations at the rhythm of Dansgaard-Oeschger (D-O) cycles. In some cases δ¹³C also varies at the D-O scale. The D-O frequency in δ¹³C is especially notable during MIS 3 from 48 ka to 30 ka, and suggests significant response of the vegetation to D-O-related climate forcing. The δ¹⁸O and δ¹³C oscillations can be compared to the sequence of Greenland Interstadial (GIS) and Heinrich (H) Events. My interpretation of the Crevice Cave record puts the controversial H5/GIS 12 transition right at 45 ka, consistent with some of the early Greenland ice chronologies, but inconsistent with some of the later chronologies as well as with other speleothem-ice core correlations put forward, which place it about 3,000 years earlier.