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Pleistocene Pluvial Lakes in East Africa

Pleistocene Pluvial Lakes in East Africa. Morgan Monz. Outline. Locations Modern climates Evidence for pluvial Lakes Pleistocene glaciation Specific pluvial lakes. Location. Victoria Tanganyika Malawi. (http://www.biomedcentral.com/content/figures/1471-2148-5-17-1-l.jpg).

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Pleistocene Pluvial Lakes in East Africa

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  1. Pleistocene Pluvial Lakes in East Africa Morgan Monz

  2. Outline • Locations • Modern climates • Evidence for pluvial Lakes • Pleistocene glaciation • Specific pluvial lakes

  3. Location • Victoria • Tanganyika • Malawi (http://www.biomedcentral.com/content/figures/1471-2148-5-17-1-l.jpg)

  4. Modern Day Climates • Arid to semi arid • Climate trend • Ratio of precipitation to potential evaporation (PET) (http://www.grida.no/images/series/vg-africa/graphics/25-aridity.jpg)

  5. Hydrologic cycle • Hadley Cells • Intertropical Convergence Zone (ITCZ) • Bimodal distribution (http://upload.wikimedia.org/wikipedia/commons/d/d7/ITCZ_january-july.png)

  6. Evidence for Pluvial Lakes • Geomorphologic • Geochemical • Archeological (http://farm3.staticflickr.com/2557/5774714465_db908f9385_z.jpg)

  7. Glaciation in Pleistocene • Three major periods • 30% of Earth’s surface was glaciated periodically • Cooler climates lead to less evaporation and less precipitation

  8. Glaciation in Pleistocene • Abrupt Termination of LGM • Milankovitch cycles • Increased insolation http://user.gs.rmit.edu.au/caa/global/graphics/insolation.jpg

  9. Lake Victoria • Shallow basin between branches of rift valley • Levels of total organic carbon and hydrogen content • Paleosol records • Seismic profiles (http://www.eoearth.org/files/119601_119700/119602/400px-Lake_victoria_basin.jpg)

  10. Lake Tanganyika • Occupies several rift basins within the Western Rift Valley • Two intervals of dramatic drop during late pleistocene • Pollen records (http://www.ncdc.noaa.gov/paleo/pubs/tierney2008/tanganyika.jpg)

  11. Lake Malawi • Rift Basin along the East African Rift • Diatom assemblages • About a 100 m drop in lake levels with the Last Glacial Maximum (http://www.eosnap.com/public/media/2011/11/malawi/20111108-malawi-thumb.jpg)

  12. Summary • East Africa has experienced a variety of climatic conditions • Large scale glaciation can be correlated to pluvial periods • Evidence for multiple dramatic lake level fluctuations in East Africa

  13. References • Anderson, D.E., Goudie, A.S., and Parker, A.G., 1007: Global environments through the Quaternary. New York: Oxford University Press; 131-138 pp. • Barker, P., R. Telford, F. Gasse and F. Thevenon, 2002: Late Pleistocene and Holocene palaeohydrology of Lake Rukwa, Tanzania, inferred from diatom analysis. Palaeogeography, Palaeoclimatology, Palaeoecology, v. 187, pp. 295-305. • Burrough, S.L., D.S.G. Thomas and R.M. Bailey, 2009: Mega Lake in the Kalahari; a late Pleistocene record of the PalaeolakeMakgadikgadi system. Quaternary Science Reviews, v. 28, pp. 1392-1411. • Clark, P.U., Alley, R.B., and Pollard, D., 1999: Northern hemisphere ice-sheet influences on global climate change. Science Magazine, V. 286, pp. 1104-1111. • Damanati, B., 2000: Holocene lake records in the Northern Hemisphere of Africa. Journal of African Earth Sciences, v. 31, pp. 253-262. • deMenocal, P., Ortiz, J., Guilderson, T., Adkins, J., Sarnthein, M., Baker, L., and Yarusinsky, M., 2000: Abrupt onset and termination of African Humid Period: rapid climate responses to gradual insolation forcing. Quaternary Science Reviews, v. 19, pp. 347-361. • Garcin, Y., A. Junginger, M. Daniel, D.O. Olago, M.R. Strecker and M.H. Trauth, 2009: Late Pleistocene-Holocene rise and collapse of Lake Suguta, northern Kenya Rift. Quaternary Science Reviews, v. 28, pp. 911-925. • Gasse, F., 2000: Hydrological changes in the African tropics since the Last Glacial Maximum. Quaternary Science Reviews, v. 19, pp. 189-211. • Goudie, A., 1992: Environmental change, contemporary problems in geography. New York: Oxford University Press; 106-112 pp. • Hastenrath, S., 2000: Variations of East Africa climate during the past two centuries. Climatic Change, v. 50, pp. 209-217. • Kieniewicz, J.M. and J.R. Smith, 2007: Hydrologic and climatic implications of stable isotope and minor element analyses of authigenic calcite silts and gastropod shells from a mid-pleistocene pluvial lake, Western Desert, Egypt. Quaternary Research, v. 68, pp. 431-444. • Konecky, B.L., J.M. Russell, T.C. Johnson, E.T. Brown, M.A. Berke, J.P. Werne and Y. Huang, 2011: Atmospheric circulation patterns during the late Pleistocene climate changes at Lake Malawi, Africa. Earth and Planetary Science Letters, v. 312, pp. 318-326. • Nicholson, S.E., and Flohn, H., 1980: African environmental and climatic changes and the general atmospheric circulation in late Pleistocene and Holocene. Climatic Change, v. 2, pp. 313-348. • Nicholson, S.E., 2000: The nature of rainfall variability over Africa on time scales of decades to millennia. Global and Planetary Change, v. 26, pp. 137-158. • Sultan, B., and Janicot, S., 2000: Abrupt shift of the ITCZ over West Africa and intra-seasonal variability. Geophysical Research Letters, v. 27, pp. 3353-3356. • Trauth, M.H., Maslin, M.A., Deino, A.L., Strecker, M.R., Bergner, A.G.N., and Duhnforth, M., 2007: High and low-latitude forcing of Plio-Pleistocene East African climate and human evolution. Journal of Human Evolution, v. 53, pp. 475-486.

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