Obsidian Cliff, also known as 48YE433, was an important source of lithic materials for prehistoric peoples in Yellowstone National Park near Mammoth Hot Springs, WY. The cliff was named by Philetus Norris, the second park superintendent in 1878. It was declared a National Historic Landmark in 1996. Many studies have been done on the composition of the obsidian from Obsidian Cliff and how the obsidian from Obsidian Cliff was distributed. This research has provided evidence of the direction and extent of prehistoric trade networks.