Here's a nice shot of Cooper standing on the ~5 meters of coarse fluvial gravel that sits on the Bogus Rim lava approximately 1000' feet above the Owyhee River. The gravel is composed entirely of basalt (~90%) and rhyolite (~10%) clasts. It is only well exposed at spotty locations along the rim. The Bogus Rim lava comprises only the few meters at the top of the exposed section. The remainder is the undivided Bogus lavas which filled deep paleotopography in this area.