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This high driftwood deposit is located at River,mile 233,7 on the right bank at the lower end of 234,mile rapid (fig, 14A), and was revisited on November 9, 2002, An old rusty metal can was fonnd placed adjacent to the top of the deposit (fig. 14B), This can was likely left by the Birdseye Expedition rodman; the presence of this Can suggests strongly that this deposit was the one surveyed in 1923 by the Birdseye Expedition. As indicated in the 1925 Stevens memorandum, the great height of this deposit above the 112,000 ft3/s wateHurface elevation surveyed in 1923 suggests that this deposit was formed during a flood with a peak discharge much greater than that of the 170,000 ft3/s 1921 flood. The presence of milled lumber (fig, 14C) indicates that this deposit was formed during a flood that occurred after white settlement of the Colorado River Basin upstream from Grand Canyon. Thus, it is likely that this driftwood deposit was formed during the 1884 flood. Revised Estimate olthe Peak Discharge olthe 1884 Flood at Lees Ferry Linear and power,law extrapolation of the stage, discharge rating curve at the Lees FelT)' Gage suggests that the peak discharge of the July 1884 flood was between 199,000 and 228,000 ft3/s (fig, 12A). This discharge range brackets the estimated 214,000 ft3/s peak discharge for this flood at the Grand Canyon gaging station (fig. 9D), and overlaps with the range of 210,000 to 250,000 ft3/s originally estimated by the USGS for the peak discharge of this flood at various sites between Lees Feny and River,mile 233,7. Based on the estimates at Lees Ferry, the revised estimate at the Grand Canyon gaging station, and the previous estimate made at River, mile 233,7, the peak discharge of the July 1884 flood, at two significant figures, was approximately 21O,000:t30,000 ft3/s at Lees Feny and through Grand Canyon (fig. 13). ImplicatiDns fDr PreviDus Estimates Df PaleDflDDd Discharges 0' Connor and others (1994) detennined that during the last 4,500 years, 15 floods at Lees Feny had peak discharges larger than 190,000 ft3/s, Ten of these floods had peak discharges larger than 240,000 ft3/s dUling the last 2,100-2,300 years, and one flood that OCCUlTed 1,200-1,600 years ago had a peak discharge exceeding 490,000 ft3/s. On the basis of the data presented in this study, the discharges of these paleofloods are overestimated, O'Connor and others (1994) conducted their paleoflood study in the reach between the Lower Staff Gage and Cathedral Wash, and the principal stratigraphic evidence was at "Axehandle Alcove," 2.2 miles downstream from the Lees Feny Gage (figs. IB and 4A). They speculated that a flood deposit at the top of their section, "GI," was deposited during the July 1884 flood, They estimated their paleoflood discharges by using a step,backwater model with the published 300,000 ft3/s peak discharge of the July 1884 flood as a guide. In their calculations, they did not take into account the fact that the water,sUlface slopes in this reach decrease with increasing stage as backwatered flow conditions develop in the reach. In fact, water, surface slopes computed by O'Connor and others (1994) steepen with increasing stage. As shown in fig, 4A, it is more likely that "G I" was deposited near the 170,000 ft3/s peak discharge of the June Inl flood. Because the Axehandle Alcove site is just downstream from the Lower Staff Gage, discharges can be directly assigned to these flood deposits on the basis of the data presented in this paper. On May 17, 1941, the discharge of the Colorado River was approximately 120,000 ft3/s. The stage associated with this flood was observed to be 28.1 ft on the Lower Staff Gage. which corresponds to an elevation of 3, 122.0 above sea level. Extrapolation of the 120,000 ft3/s water,surface profile downstream indicates that the elevation of the May 17, 1941, water surface was approximately 3,120.1 ft above sea level at the Axehandle Alcove site, This elevation is rougWy equivalent to the elevation of the base of O'Connor and others (1994) stratigraphic section, If the channel geometry in this reach in 1941 were similar to its geometry 3,000-4,500 years ago, the lowermost flood deposit preserved in Axehandle Alcove was deposited by a flood with a peak discharge jnst above 120,000 ft3 Is, On the basis of fig, 4A, the elevation of the water surface during the peak of the 1921 flood at Axehandle Alcove was probably about 3,130,6 ft above sea level. This elevation is about 1.3 ft higher than the elevation of the deposit "G I" in fig. 3 in O'Connor and others (1994), and is similar to the highest elevation repOlted in the reach for "G I." Thus, it is likely that "G I" was not deposited during the 1884 flood, but rather during the 1921 flood. (l2Z3l} Colorado River Floods at lees Ferry 31