Lake Bonneville (which existed during marine oxygen isotope stage 2, 30-10 ka) occupied a topographically closed basin at the eastern margin of the Great Basin in the Basin and Range physiographic province. Lake Bonneville was the last deep lake cycle in the Bonneville basin (Fig 1). At its maximum height of 1552 m above sea level, the lake covered an area of approximately 51,281 km2 (Currey et al., 1984) making it the largest late Pleistocene lake in the Great Basin (Grayson, 1993). Lake Bonneville began to rise about 30 ka and continued to transgress with minor fluctuations to its highest level (1552 m), where it formed the Bonneville shoreline sometime shortly after 15.3 ka (Oviatt et al., 1992) (Fig. 3). At the Bonneville shoreline, the lake overflowed intermittently near Red Rock Pass into the Snake River drainage of southeastern Idaho (Currey et al., 1984). The overflow waters eventually caused hydraulic failure of relatively unconsolidated sediments forming the rim near Red Rock Pass and scoured a channel down to well-indurated materials. This event released the catastrophic Bonneville Flood at approximately 15 ka (Currey and Oviatt, 1985; Jarrett and Malde, 1987). The flood lowered lake level approximately 100 m to the Provo shoreline, where the lake overflowed intermittently until the post-Provo regression (14 - 10 ka) ended the Bonneville deep lake cycle (Oviatt et al., 1992).