Here's why climbers use supplemental oxygen to climb Mount Everest. Also, the curtailment of the 2014 Everest climbing season following a deadly avalanche.
The vast Altiplano plateau in the South American Andes Mountains formed not gradually, but through rapid growth spurts, a new geological study suggests.
New U.S. government report on climate change - first in five years - due out May 6. It outlines ongoing effects of a warming climate in the U.S. Northeast.
There has been uplift and minor earthquake activity on Mount St. Helens, an active volcano in Washington state, but there are no signs that it is about to erupt.
This video shows happened in Baltimore's busy Charles Village neighborhood Wednesday, when a retaining wall buckled and sent cars and mud tumbling onto railroad tracks below.