From Green River Overlook, the surrounding landscape includes the Land of Standing Rocks, where high plateaus and spires have been eroded from dark brown shale into formations such as Lizard Rock, The Plug, Chimney Rock, and The Wall, 15 miles southwest. The Maze, west of the Green and Colorado Rivers in Canyonlands National Park, is a 114-square-mile labyrinth of mesas, steep-sided buttes, and slender towers marked by bands of red and white sandstone. Nearby landmarks include Elaterite Butte, named for a dark-brown mineral found in the area, and Ekker Butte, named for the Ekker family, pioneer ranchers nearby in Glen Canyon National Recreation Area. The Orange Cliffs, named by John Wesley Powell in 1869, rise as vertical faces of Wingate Sandstone 300 to 450 feet high. The Green River begins in Wyoming's Wind River Range and joins the Colorado River 20 miles below this point, dividing the Island in the Sky District from the Maze District. White Rim Sandstone, formed from ancient coastal sand dunes, creates a sharply defined rim about 1,300 feet below this point and serves as a protective cap rock on buttes and spires, including Turks Head, which Powell named for its resemblance to a Turkish turban. Farther southwest, the Henry Mountains were the last mountain range added to the map of the lower 48 states, with Mount Ellen as the highest peak, and Cleopatra's Chair stands out on the skyline as a Navajo Sandstone formation in Glen Canyon National Recreation Area.