Black Sand Basin

One of Yellowstone National Park's most colorful geothermal features is the Black Sand Basin. It is named for the small granules of obsidian which are distributed throughout the area.

Yellowstone National Park--the first and oldest national park in the world--is located in the western states of Wyoming, Montana and Idaho. It covers 3,845 square miles (8879 kilometers²), mostly in the northwest corner of Wyoming. It is most famous for its geothermal attractions--geysers, hot springs, among them the world's most famous geyser, Old Faithful.

Image credit: Gwendolyn E. Morgan