How old is California's Yosemite Valley?

First-time visitors to Yosemite Valley gape in awe at the sheer granite wall of El Capitan and the neatly sliced face of Half Dome, aware, perhaps vaguely, that rain and glaciers must have taken a long time to cut and sculpt ...

Some asteroids 'aged early' by sun, NASA finds

Scientists from NASA's OSIRIS-REx mission recently learned that surface regeneration happens a lot quicker on asteroids than on Earth. By analyzing rock fractures on asteroid Bennu from high-resolution images taken by the ...

Mars Express peers into Mars' 'Grand Canyon'

The latest image release from ESA's Mars Express takes us over two ruptures in the Martian crust that form part of the mighty Valles Marineris canyon system.

Biologists' fears confirmed on the lower Colorado River

For National Park Service fisheries biologist Jeff Arnold, it was a moment he'd been dreading. Bare-legged in sandals, he was pulling in a net in a shallow backwater of the lower Colorado River last week, when he spotted ...

Expanding drought leaves western US scrambling for water

Tumbleweeds drift along the Rio Grande as sand bars within its banks grow wider. Smoke from distant wildfires and dust kicked up by intense spring winds fill the valley, exacerbating the feeling of distress that is beginning ...

Dwindling water levels of Lake Powell seen from space

After decades of drought, water levels in Lake Powell, the second-largest human-made reservoir in the United States, have shrunk to its lowest level since it was created more than 50 years ago, threatening millions of people ...

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