We present stable oxygen and carbon isotope data (δ¹⁸O and δ¹³C ) and U-Th chronology data from five speleothems from Cape Limeworks Cave 1 near Robertson, Western Cape, South Africa (33.73S°, 19.77E°). The data set covers the time interval between 240 and 670 ka BP with hiatuses at 630-500 ka and 360-310 ka. Stable isotope ratios range between -6.5 and -3.7 ‰ for δ¹⁸O and -11.0 and -8.5 ‰ for δ¹³C. Analyses of the dispersion of the δ¹⁸O and δ¹³C data sets suggest that the highly diverse western part of the Cape Floristic Region experienced climatic stability across several glacial-interglacial cycles when compared to less diverse Mediterranean Climate Regions and the eastern parts of the Cape Floristic Region. This result provides support for the hypothesis that lower extinction rates associated with Pleistocene biome stability may explain the higher diversity in the CFR relative to other MCEs.

Speleothems were extracted from the cave using a hammer and chisels and stable isotopes were analyzed at the Geological Survey of Israel using methods described in Bar-Matthews et al., (2003, Geochimica et Cosmochimica Acta, 67, 3181–3199. https://doi.org/10.1016/S0016-7037(02)01031-1) and Bar-Matthews et al., (1997, Quaternary Research, 47, 155–168. https://doi.org/10.1006/qres.1997.1883).

U-series dating was done at the Geological Survey of Israel following methods described in Grant et al., (2012, Nature, 491(7426), 744–747. https://doi.org/10.1038/nature11593) and at the University of Minnesota following methods described in Edwards et al., (1987, Earth and Planetary Science Letters, 81, 175–192), Shen et al., (2012, Geochimica et Cosmochimica Acta, 99, 71–86. https://doi.org/10.1016/J.GCA.2012.09.018) and Cheng et al., (2013, Earth and Planetary Science Letters, 371–372, 82–91. https://doi.org/10.1016/j.epsl.2013.04.006)

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