DESERT PALEOENVIRONMENTAL DATA FROM CAVE SPELEOTHEMS WITH EXAMPLES FROM THE CHIHUAHUAN, SOMALI-CHALBI, AND KALAHARI DESERTS

Pollen-bearing lake, bog, and spring sediments are relatively scarce in many arid and semiarid regions of the world, and few are dateable beyond the 14C range. We have obtained pollen spectra from speleothems collected from caves in the Somali-Chalbi and Kalahari deserts suggesting that these deposits may be an important future source of desert paleovegetation data. As cave speleothems can be dated by the 230Th/234U method to c. 350,000 yr B.P., and by the TL and ESR methods potentially to 1 m.y. B.P., and can sometimes give paleotemperature and paleohydrologic data, they could provide a first glimpse of desert paleoenvironments during isotope stages 4-9. Ages of speleothems from the Chihuahuan, Kalahari, and Somali-Chalbi deserts suggest that there was more available moisture in the southwestern U.S.A. and in northwestern Bostwana during glacials and interstadials of the last c. 300,000 years, but that wetter conditions in the Horn of Africa corresponded with interglacials and perhaps to a lesser extent with interstadials. Pollen from three northern Somalia speleothems indicate more mesic conditions in the Horn of Africa at 10,000, 11,800, and 176,500 yr B.P., while speleothem pollen spectra from Matupi Cave in northeastern Zaire, presently surrounded by tropical rainforest, suggest a savanna grassland at this cave c. 14,000 yr B.P. © 1990.