The morning is cold and crisp at Sunset Crater National Monument. The group hikes a trail from which lava flows, splatter cones, squeeze-ups, and lava tubes are visible. The cinder cone itself is believed to have formed from a series of eruptions that started in 1064 AD. This makes it the most recent episode of volcanism in Northern Arizona. For this reason, this cinder cone is a particularly well preserved example of this geologically ephemeral type of mountain. There's nothing to say there won't be more eruptions in the future.