Geologically, the Rio Grande Gorge is a rift valley, a separation in the earth’s crust caused by faulting and other earth movements when the North American and Pacific plates scraped against each other some twenty-nine million years ago. The canyon ecosystem descends 800 feet (240 m) from rim to river, creating a unique diversity in plant and animal life. Ancient pinon and juniper forests are home to 500-year-old trees. Wildlife include mule deer, red-tailed hawk, mountain blue-bird, and prairie dog. We saw Bighorn Mountain Sheep feeding in the gorge.