Episodes of late Holocene aridity recorded by stalagmites from Devil's Icebox Cave, central Missouri, USA

Two stalagmites from Devil's Icebox Cave, central Missouri, display similar delta C-13 and delta C-18 values and trends during the late Holocene. Positive delta(13) C-excursions at 3.5-2.6 ka and 1.2-0.9 ka are interpreted to reflect drier conditions. These elevated stalagmite delta C-13 values could have plausibly been driven by increasing C-4 plant abundances over the cave or an increased contribution of bedrock carbon, both of which could reflect decreased effective moisture. A lack of corresponding oxygen isotopic anomalies during these intervals suggests that neither mean annual temperature nor the seasonality of precipitation changed concomitantly with dryness. Both of the 613 C excursions identified in our stalagmite record are roughly coincident with dry intervals from a number of sites located across the Great Plains. (c) 2007 University of Washington. All rights reserved.