Evidence of late Quaternary environments in northwestern Georgia from sediments preserved in Red Spider Cave

Carbon-14 ages of nine speleothems from Red Spider Cave indicate that speleothem deposition occurred predominantly during warmer phases of the last 40,000 years. Biotic activity above the cave may have been suppressed during the colder climatic periods, reducing soil CO2 levels. This may have lowered limestone solution rates and either slowed speleothem growth or interrupted deposition altogether. Remnants of a elastic fill up to 3 m thick are present within the cave. Speleothem age data indicate that this fill was emplaced after 26,000 yr. B.P. and had been largely eroded by 11,000 yr. B.P. The sediments may have been washed into the cave at the interstadialfull glacial transition or during full glacial times when the vegetation became more open and temperatures cold enough for freeze-thaw weathering and solifluction activity in the area. Pollen grains recovered from 11 speleothems suggest that during the warmer periods of the last 40,000 years the vegetation near Red Spider Cave was deciduous forest dominated by oak. Large percentages of herb pollen in speleothem pollen spectra for 39,000, 30,000, and before 11,000 yr. B.P. indicate that the forest at these times may have been more open and interspersed with species-rich meadows. The presence of aquatic pollen in all but mid- and late-Holocene-age speleothems implies more available moisture during interstadial, late glacial, and early Holocene times. Speleothem pollen spectra also indicate mixed mesophytic forest near Red Spider Cave at 9905 yr. B.P., 1730 yr. B.P, and prior to European settlement of the area. Pollen spectra for two active straw stalactites were entirely representative of the present oak-pine-hickory forest near the cave, indicating that valid paleovegetation data can be obtained for this site from speleothem pollen spectra.