Inside Yellowstone - Sheepeater Cliff
Sheepeater Cliff Photos - Earths Extremophiles Website
Basalt - Wikipedia
Basalt - About.com
Columnar Basalt Photos - Centripetal Notion
Did You Know?
There are more people hurt by bison than by bears each year in Yellowstone. Park regulations state that visitors must stay at least 25 yards away from bison or elk and 100 yards away from bears.