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Show Owens River chain of lakes: The 3.2 million- year Searles Lake history, southeast California George I. Smith Geologist- Emeritus U. S. Geological Survey Menlo Park, California ABSTRACT The modern Owens River, which drains south along the east side of the Sierra Nevada, carries the voluminous runoff from the highest part of that range. In 1872, the Owens River terminated in Owens Lake, which at that time was - 15 m deep; it is now dry. During parts of the Pleistocene, greater precipitation caused the Owens River flow to increase greatly, causing Owens Lake to overflow and drain to the south, forming lakes in four successively- lower- elevation valleys. The number of lakes in the Owens River chain, and the size of the last lake, reflected the balance between precipitation and runoff vs. the cumulative evaporation from the lakes in its chain. The maximum increase in Pleistocene river volumes was about ~ 8 times its 1872 flow. Lacustrine deposition in Searles Valley, the second Pleistocene lake downstream from Owens Lake, began 3.2 Ma. Deposits in it range from deep perennial lakes, through playa lakes, to salt flats. Comparing this Searles record with that from Owens Lake, which extends back to 800 ka, shows that near the beginning of climate changes toward drier periods, Searles Lake ( which lies in a very arid setting) was the first of the two basins to record sedimentary evidence of this change. Near the beginning of changes toward wetter periods, Owens Lake ( which lies in a much less July 21,1997 9: 15 1 |
