Formed over thousands of years of erosion caused by hydrothermal activity, water and other natural forces, the Grand ... of the canyon, including its many colors and rock formations.

A research team outlines how it identified and bestowed a moniker upon a previously unexplored 500 million-year-old Grand Canyon formation: The Frenchman Mountain Dolostone. The newly named rock ...

who studied the "Tonto Group", a 0.3-mile-thick collection of five rock formations that are exposed along the sides of the canyon. "The Tonto Group of Grand Canyon holds a treasure trove of ...