Obsidian Cliff, YNP.
![Obsidian Cliff, Yellowstone National Park....](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/vhp_img109.jpg?itok=zcbn6L_B)
Detailed Description
Obsidian Cliff exposes the interior of a thick rhyolite lava flow erupted about 180,000 years ago. The vertical columns are cooling fractures that formed as the thick lava flow cooled and crystallized. The flow consists of obsidian, a dark volcanic glass.
Sources/Usage
Public Domain.