Obsidian is a naturally occurring volcanic glass that forms when viscous rhyolite magma, which is rich in silica, erupts as a lava flow then cools rapidly. The rapid cooling and high viscosity of the ...

X-ray technology has given researchers a glimpse at the reaches of this landmark and its importance to Indigenous people. Natalie Behring for The New York Times Obsidian is among the most prized tool ...

Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week's contribution is from Mark Stelten, research geologist with ...

Thousands of years before Euro-Americans “discovered” the bubbling mudpots and eruptive geysers of what is now Yellowstone National Park, early Americans were spending part of their summer camping in ...

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