Monument Valley is considered one of the natural wonders of the world because of the beauty of the enormous "monuments" of stone that have evolved from nature: wind and rain chip away at the land over millions of years, eroding the plateau, leaving a vast landscape of tourist opportunities.
Grand Canyon National Park Arizona The Grand Canyon was formed by 5-6 million years of erosion as the Colorado River craved its way through multiple layers of rock. The Grand Canyon is approximately 277 miles long. Its deepest point from the rim to the river is 6000 feet. It was designated a National Park in 1919 and receives nearly 5 million visitors a year. Thanks to Roger :)