| Summary: | from a southward deflection of the jet steam due to the presence of a continental ice sheet in central North America. This mechanism also may have governed the two earlier intervals of fast growth in the speleothems (and inferred wetter climate). Ice volumes were lower and temperatures in central North America were higher during these two earlier glacial intervals than during the Last Glacial Maximum, however. The potential effects of temporal variations in precession of Earth's orbit on regional effective moisture may provide an additional mechanism for increased effective moisture coincident with the observed intervals of increased speleothem growth. The stalagmites all exhibit a large drop in growth rate between 15 and 12 ka, and they show very slow growth up to the present, consistent with drier climate during the Holocene. These results illustrate that speleothem growth rates can reflect the regional response of a hydrologic system to regional and global climate variability.
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