Colorado Plateau

Earth Notes: Martin Litton

Apr 3, 2019
Courtesy John Blaustein

Fifty years ago, a World War Two glider pilot and Sierra Club board member started a successful business offering dory trips down the Colorado River in Grand Canyon. Along the way, he became a warrior for wilderness.

Earth Notes: Moqui Marbles

Mar 27, 2019
Gary Alpert

For those who enjoy pleasantly poking around the Colorado Plateau, there’s an endless array of fascinating geologic curiosities. Among them are intriguing stones called Moqui marbles—brownish-black rocks, often roundish but with a variety of fanciful appendages, ranging from pea to grapefruit-size.

Earth Notes: Cowboy Alcoves

Mar 20, 2019
Michael Engelhard

Throughout the Southwest, range riders camped in stone hollows for the same reason they wore broad-brimmed hats: to shelter from rain, wind, snow, and the sky’s fearsome glare.

U.S. Forest Service

The San Francisco Volcanic Field in northern Arizona is full of spiky lava flows. Some seem as fresh as if they were laid down yesterday. But how old are they, really? Scientists are now dating these ancient volcanic eruptions with a method that involves a curious kind of clock—the cosmic rays emitted by stars.


When people think of sage-grouse, they may think of them as birds of far northern valleys swathed in grey-green sagebrush. But there’s a distinct—and lesser-known—species that lives south of the Colorado River in Utah and Colorado. It’s the Gunnison sage-grouse, a smaller cousin of the greater sage-grouse.