Arizona’s Grand Canyon, the great gorge of the Colorado River, is one of the natural wonders of the world. The canyon reaches depths greater than 1 mile (1.6 km), and its multicolored rock layers and steep rims are renowned for their beauty. After visiting the Grand Canyon in 1903, US President Theodore Roosevelt—an avid conservationist—became a major proponent of its preservation and designated it a US National Monument on January 11, 1908. Who fought against his efforts? Discuss