At the edge of the Wonderland of Rocks stands the Wall Street Mill, the finest remaining example in the park of a gold processing mill. The site preserves a two-stamp mill, the building that covers it, the well that supplied water, and the well pump. Native Americans earlier used the nearby natural food sources and rock shelters, and in the late 1800s William McHaney dug a well that became a popular cattle watering area. In 1928, Oran Booth and Earle McInnes filed a claim at the well site, built a cabin, and named the place Wall Street, but they soon left for other opportunities. During the Depression, when the region experienced a second gold rush, longtime rancher-miner Bill Keys recognized the need for a gold processing mill. On July 1, 1930, he filed a milling claim on the site, completed the bunk house, built an outhouse, and gathered a two-stamp mill ore crusher and other machinery from area mine and mill sites to assemble his mill. For a fee, he processed ore for small-mine operators and also milled gold ore from his own mines. After gold was removed from the ore, it went back to the miner, to a smelter in Mojave, or to the U.S. Mint in San Francisco. A twelve-horsepower gasoline engine, working through shafts, belts, and pulleys, powered the 1891-built mill machinery. Keys operated the mill on an as-needed basis from 1930 to 1966, last using it in 1966, and he died in 1969. In 1975, the Wall Street Stamp Mill was entered in the National Register of Historic Sites for its local technological and mechanical significance as a complete gold ore crushing mill featuring late nineteenth-century two-stamp mill machinery.