Nature
Amethyst Mountain, a 9,609-foot summit in Yellowstone National Park, stands at the center and highest point of a ridge between the Lamar River and Deep Creek in northwestern Wyoming. Named in 1872 for amethysts found on its summit, it is also known for opal and especially for its exposed petrified forests. Its slopes include part of the Yellowstone Petrified Forest and the long-studied Fossil Forest, where silicified wood and buried forest beds reveal how volcanic mudflows, streams, and lahars preserved and redeposited ancient trees. The mountain’s rocks, laid down in the Eocene from eroded volcanic material, make it important both scenically and for geological and paleobotanical research.
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Mammoth, Wyoming · United States
