Earth Observation: Grand Canyon Geology Lessons on View

The Grand Canyon in northern Arizona is a favorite for astronauts shooting photos from the International Space Station, as well as one of the best-known tourist attractions in the world. 

The steep walls of the Colorado River canyon and its many side canyons make an intricate landscape that contrasts with the dark green, forested plateau to the north and south.

The Colorado River has done all the erosional work of carving away cubic kilometers of rock in a geologically short period of time.

Visible as a darker line snaking along the bottom of the canyon, the river lies at an altitude of 715 meters (2,345 feet), thousands of meters below the North and South Rims.

Temperatures are furnace-like on the river banks in the summer, but Grand Canyon Village, the classic outlook point for visitors, enjoys a milder climate at an altitude of 2,100 meters (6,890 feet).

The Grand Canyon has become a geologic icon—a place where you can almost sense the invisible tectonic forces within the Earth.

The North and South Rims are part of the Kaibab Plateau, a gentle tectonic swell in the landscape. The uplift of the plateau had two pronounced effects on the landscape that show up in this image.

First, in drier parts of the world, forests usually indicate higher places; higher altitudes are cooler and wetter, conditions that allow trees to grow.

The other geologic lesson on view is the canyon itself. Geologists now know that a river can cut a canyon only if the Earth surface rises vertically.

If such uplift is not rapid, a river can maintain its course by eroding huge quantities of rock and forming a canyon.

Image Credit: NASA

Antarctic ice: UK Geologists find Massive valley deeper than Grand Canyon

Antarctic field camp located on the ice sheet surface directly over the hidden Ellsworth Trough 

Credit: Neil Ross 

A massive ancient subglacial trough, deeper than the Grand Canyon, exists under the ice of Antarctica, a team of UK experts says.

Scientists from Bristol University, Newcastle University and the British Antarctic Survey discovered the massive valley during three seasons of charting the Ellsworth Subglacial Highlands, an ancient mountain range buried beneath several kilometers of antarctic ice.

They used data from satellites and ice-penetrating radars towed behind snowmobiles and on-board small aircraft.

The massive subglacial valley is almost 2 miles deep, almost 190 miles long and up to 15 miles wide. In places, the floor of this valley is more than 6,500 feet below sea level, the researchers said.

Neil Ross

"The discovery of this huge trough, and the characterization of the surrounding mountainous landscape, was incredibly serendipitous," Newcastle University physical geographer Neil Ross said.

"We had acquired ice penetrating radar data from both ends of this huge hidden valley, but we had no information to tell us what was in between," he said.

"Satellite data was used to fill the gap, because despite being covered beneath several kilometers of ice, the valley is so vast that it can be seen from space."

A moving ice field carved the deep valley and its surrounding mountains millions of years ago, the scientists said.

"To me, this just goes to demonstrate how little we still know about the surface of our own planet," Ross said.

"The discovery and exploration of hidden, previously unknown landscapes is still possible and incredibly exciting, even now."

More information: 'Evidence from ice shelves for channelized meltwater flow beneath the Antarctic Ice Sheet' - Nature Geoscience 6, 945–948 (2013) doi:10.1038/ngeo1977

NASA ISS Images: Grand Canyon, Colorado river

NASA: Pictures from ISS - Grand Canyon, Niagara Falls & Arabian Desert