A massive landslide would have dammed the Colorado River, forming a deep lake that has since dried up. A meteorite impact ...

This surprising connection between Arizona's world-renowned geological features stretches back 56,000 years, to when a ...

Many visitors expect to see stalactites and stalagmites galore in Mammoth Cave but are surprised when they don't see many of ...

A new study suggests ancient wood floated into a cave far above the Colorado River when a meteorite-induced earthquake ...

Oregon's growing list of dark sky places makes it one of the most ideal states for stargazers. Oregon has seven dark sky ...