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Science 18 December 1981:
Vol. 214. no. 4527, pp. 1299 - 1305
DOI: 10.1126/science.214.4527.1299
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Articles

Late Quaternary Environmental History of Lake Valencia, Venezuela

J. Platt Bradbury 1, B. Leyden 2, M. Salgado-Labouriau 3, W. M. Lewis Jr. 4, C. Schubert 3, M. W. Binford 5, D. G. Frey 6, D. R. Whitehead 6, and F. H. Weibezahn 7

1 Geologist at the U. S. Geological Survey, Denver, Colorado 80225
2 Associated with the University of Southern Florida, Tampa
3 Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela
4 Professor of environmental, population, and organismic biology at the University of Colorado, Boulder
5 Research associate at the Florida State Museum, University of Florida, Gainesville
6 Professors of biology at Indiana University, Bloomington
7 Escuela de Biologia, Universidad Central, Caracas, Venezuela

Chemical, paleontological, and mineralogical analyses of a 7.5-meter core from the middle of Lake Valencia, Venezuela, have provided information on the paleoclimatic history of this low-elevation, low-latitude site for the last 13,000 years. The data show that dry climates existed in this region from 13,000 years before present (B.P.) until about 10,000 years B.P. The Lake Valencia Basin was occupied by intermittent saline marshes at that time. About 10,000 years B.P., a permanent lake of fluctuating salinity formed and arboreal plant communities replaced the earlier dominant xeric herbaceous vegetation and marsh plants. By 8500 years B.P., Lake Valencia reached moderate to low salinities and discharged water; the modern vegetation became established at that time. After 8500 years B.P., the lake twice ceased discharging as a result of reduced watershed moisture. The second of these drying episodes is still in progress and has been aggravated by human activities in the watershed.


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