My first glimpse at the fortress-like spires near Antelope, Oregon came late in the day on September 23rd. It looked like I’d just landed on an alien planet. This is the Clarno unit of the John Day Fossil beds. The Clarno is home to the oldest rocks in the fossil beds–the solidified remains of volcanic mudflows–known as lahars–that inundated what were then tropical forests, between 40 and 54 million years ago.