RADIOCARBON AGES AND ENVIRONMENTS OF DEPOSITION OF THE WONO AND TREGOHOT-SPRINGS TEPHRA LAYERS IN THE PYRAMID LAKE SUBBASIN, NEVADA

Uncalibrated radiocarbon data from core PLC92B taken from Wizards Cove in the Pyramid Lake subbasin indicate that the Trego Hot Springs and Wono tephra layers were deposited 23,200+/-300 and 27,300+/-300 C-14 y r B.P. (uncorrected for reservoir effect). Sedimentological data from sites in the Pyramid Lake and Smoke Creek-Black Rock Desert subbasins indicate that the Trego Hot Springs tephra layer was deposited during a relatively dry period when Pyramid Lake was at or below its spill po int (1177 m) to the Winnemucca Lake subbasin. The Wono tephra layer wa s deposited when lake depth was controlled by spill across Emerson Pas s sill (1207 m) to the Smoke Creek-Black Rock Desert subbasin. O-18 da ta from core PLC92B also support the concept that the Trego Hot Spring s tephra fell into a relatively shallow Pyramid Lake and that the Wono tephra fell into a deeper spilling lake. (C) 1997 University of Washi ngton.