Yellowstone caldera's NW rim at Madison Junction in YNP.

Aerial view of the striking NW rim of the Yellowstone caldera and intracaldera rhyolite lava flows at Madison Junction in Yellowstone National Park. View is looking north. The steep-facing caldera wall, 500 m tall, formed when the area in the foreground collapsed during eruption of the Lava Creek Tuff 640,000 years ago. The thick West Yellowstone rhyolite lava flow erupted about 110,000 years ago, and the Nez Perce Creek flow erupted 160,000 years ago.