NASA's Mars rover Opportunity has reached its next destination — a valley called Perseverance, where the long-lived robot will scour the surface for clues about how the vast crevice formed.

Much of Yosemite Valley's impressive depth was carved since 10 million years ago, and most likely even more recently—over the past 5 million years.

Geologists have seen ridges and valleys form in real time and -- even though the work was a fast-forwarded operation done in a laboratory setting -- they now have an idea of how climate change may ...

Because Monument Valley was formed from several layers of rock with varying hardness, we are left with magnificently sculpted buttes, the result of millions of years of simple erosion by water ...

If voters approve Valley secession Nov. 5, they would create a major American city fully formed from another municipality, starting life with a built-in population of 1.35 million and an economy ...

The results suggest that valley networks formed on Mars during a semi-arid to arid climate that persisted for tens of thousands to hundreds of thousands of years.

Many of Mars’ stream valleys might have formed under an ice sheet Analysis of valley shapes might alter your mental image of a wet Mars.

The results suggest that valley networks formed on Mars during a semiarid to arid climate that persisted for tens of thousands to hundreds of thousands of years.