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Show interval suggest an age of about 3- 2 Ma. Thus, the record of Pliocene lakes in Clayton Valley is in accord with those in Rhodes Salt Marsh and Fish Lake Valley ( fig. 2). I infer the existence of a Miocene to Pliocene lake basin that included, at minimum, Soda Springs Valley and Rhodes and Columbus Salt Marshes ( fig. 1), and possibly extended north into the Walker Lake basin. This basin was disrupted by faulting and ( or) compression that lifted the area of Redlich Summit, the present- day divide underlain by lacustrine deposits. Further, the basins containing Lakes Columbus- Rennie, Clayton, and Tonopah are presently separated by very low sills and may once have formed an integrated drainage system. SUMMARY AND IMPLICATIONS Lake basins of western Nevada contain abundant evidence of pluvial lakes during the early to middle Pleistocene that were much larger than the late middle and late Pleistocene lakes. Pliocene lacustrine deposits suggest that Soda Springs, Fish Lake, and Clayton Valleys and Columbus Salt Marsh were once part of the same lake basin or drainage system. Hubbs and Miller ( 1948) proposed such " early pluvial" connections on the basis of remnant populations of Lahontan fish south of the Lahontan basin. Mifflin and Wheat ( 1979) also thought that Rhodes and Columbus Salt Marshes and Clayton Valley had once had been part of a much larger body of water. The reasons for these lake level changes may include: ( 1) increasing rain shadow through time due to uplift of the Sierra Nevada; ( 2) changes in position of the jet stream; ( 3) drainage changes that altered the size of the Lahontan drainage basin ( fig. 1); and ( 4) more moisture from the west due to a lake that once filled the Great Valley of California ( Sarna- Wojcicki, 1995). References Benson, L. V., Currey, D. R., Dorn, R. I., Lajoie, K. R., Oviatt, C. G., Robinson, S. W., Smith, G. I., and Stine, S., 1990, Chronology of expansion and contraction of four Great Basin lake systems during the past 35,000 years: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 78, p. 241- 286. Davis, J. R., 1981, Late Cenozoic geology of Clayton Valley, Nevada, and the genesis of a lithium- enriched brine: University of Texas at Austin, Ph. D. thesis, 233 p. Hubbs, C. L., and Miller, R. R., 1948, The Great Basin. II. The zoological evidence: University of Utah Bulletin, v. 38, p. 17- 166. Mifflin, M. D., and Wheat, M. M., 1979, Pluvial lakes and estimated pluvial climates of Nevada: Nevada Bureau of Mines and Geology Bulletin 94, 57 p. Miller, R. R., and Smith, G. R., 1981, Distribution and evolution of Chasmistes ( Pisces: Catostomidae) in western North America: Occasional Papers of the Museum of Zoology, Univ. Mich., v. 696, p. 1- 46. Morrison, R. B., 1991, Quaternary stratigraphic, hydrologic, and climatic history of the Great Basin, with emphasis on Lakes Lahontan, Bonneville, and Tecopa, in Morrison, R. B., ed., Quaternary Nonglacial Geology: Conterminous U. S: Boulder, Colorado, Geological Society of America, The Geology of North America, v. K- 2, p. 283- 320. Reheis, M. C., and Morrison, R. B., in press, High, old pluvial lakes of western Nevada: Guidebook, Geological Society of America Annual Meeting, Salt Lake City, October 1997. Reheis, M. C., Slate, J. L., Sarna- Wojcicki, A. M., and Meyer, C. E., 1993, A late Pliocene to middle Pleistocene pluvial lake in Fish Lake Valley, Nevada and California: Geological Society of America Bulletin, v. 105, p. 953- 967. Sarna- Wojcicki, A. M., 1995, Age, areal extent, and paleoclimatic effects of " Lake Clyde," a mid- Pleistocene lake that formed the Corcoran Clay, Great Valley, California: Abstracts for Glacial History of the Sierra Nevada, California- a symposium in memorial to Clyde Wahrhaftig, Sept. 20- 22, 1995, White Mountain Research Station, Bishop, California, 10 p. |
