Obsidian Cliff

Obsidian Cliff, also known as 48YE433, was an important source of lithic materials for prehistoric peoples in Yellowstone National Park near Mammoth Hot Springs, Wyoming, United States. The cliff was named by Philetus Norris, the second park superintendent in 1878. It was declared a National Historic Landmark in 1996.

Geography
It is located about 13 mi south of Mammoth Hot Springs, on the east side of the Mammoth-Norris section of the Grand Loop Road. The Obsidian Cliff Kiosk, just north, is also listed on the National Register. Obsidian Cliff is also located on the northern end of Beaver Lake in Yellowstone National Park. A 1988 wildfire cleared trees from the site, allowing further archaeological expeditions.

Geology
The cliff was formed from thick rhyolite lava flow that occurred about 180,000 years ago. The vertical columns are cooling fractures that formed as the thick lava flow cooled and crystallized. The Cliffs stands at an elevation of nearly 7400 ft above sea level and goes on for about half a mile. The cliffs also extend between 150 and 200 feet above Obsidian Creek. The flow consists of obsidian, a dark volcanic glass. The obsidian is most abundant at the base of the cliff and slowly tapers off to larger concentrations of pumice at the top.

Significance to Native Americans
Obsidian has been quarried from the site for the past 12,000 years. Highly valued for its sharpness, Obsidian was used by Native Americans throughout the Western United States and Canada as knives, spear/arrow tips, and other ceremonial and sharp-edged objects. Thousands of pounds of obsidian was transported thousands of miles to Ohio using the Missouri, Mississippi, and Ohio rivers between ~200BC and ~400AD for use as ceremonial goods by the Hopewell Culture.