Summer, 2015 - Thomas, Jr led Chelsea, Tom and friend Alan Williams on a hike in the Grand Canyon. The Grand Canyon is a steep-sided canyon carved by the Colorado River in the state of Arizona in the United States. It is contained within and managed by Grand Canyon National Park, the Kaibab National Forest, Grand Canyon-Parashant National Monument, the Hualapai Tribal Nation, the Havasupai people and the Navajo Nation. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, and visited it on numerous occasions to hunt and enjoy the scenery.
The Grand Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile (6,093 feet or 1,857 meters). Nearly two billion years of Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. While the specific geologic processes and timing that formed the Grand Canyon are the subject of debate by geologists, recent evidence suggests that the Colorado River established its course through the canyon at least 17 million years ago. Since that time, the Colorado River continued to erode and form the canyon to its present-day configuration.
For thousands of years, the area has been continuously inhabited by Native Americans who built settlements within the canyon and its many caves. The Pueblo people considered the Grand Canyon a holy site, and made pilgrimages to it. The first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain, who arrived in 1540.
There are approximately 1,737 known species of vascular plants, 167 species of fungi, 64 species of moss and 195 species of lichen found in Grand Canyon National Park. This variety is largely due to the 8,000 foot (2,400 m) elevation change from the Colorado River up to the highest point on the North Rim. Grand Canyon boasts a dozen endemic plants (known only within the Park's boundaries) while only ten percent of the Park's flora is exotic. Sixty-three plants found here have been given special status by the U.S. Fish and Wildlife Service.