Explorers Monument is a 4,572-foot summit in the Grand Canyon of northern Arizona, set within a bend of the Colorado River about 3.5 miles west of Mount Huethawali. Though not especially tall for the region, it rises more than 2,400 feet above the river and stands out as a major landmark for canyon travelers. Its layered geology includes the Supai Group above Redwall Limestone and the Tonto Group, creating a stepped, sheer-sided butte form typical of Grand Canyon summits. George Wharton James first called it Marcos Monument, but in 1908 the United States Geological Survey adopted Explorers Monument, honoring several explorers tied to the canyon and surrounding region.