“Ah. This is what I wanted to show you.”
The dozen teens sat in what shade could be found. The day was hot, and the sun high in the light blue, cloudless sky. The counsellor broke out Quaker bars and Pretzels and encouraged the campers to drink water.
There was a crumbling, sandy bluff which rose out of the desert and chaparral and ran along a ragged line north west. The counsellor pressed his hand against the face, shading beneath his wide-brimmed hat. The bluff face was lightly scribed with lines, which ran parallel in bands of alternating light and dark colours. He traced his finger slowly down the lines as he spoke.
“These are strata, layers of rock and sand and dirt built up over the Earth’s history. They’re a record of the planet. See here?” He stood on his tiptoes and pointed arbitrarily to lines only a few inches from the edge of the face. “The American Civil War.” And, less than an inch further down, “Christopher Columbus finds America.”
“Whoa! It’s like a tree ring.”
He traced his finger along a thick, dark line which ran only a few inches above where the rest of the face was buried below the mean ground level. He chipped a few pieces from the face with his fingernail; in his palm, he showed them to the campers.
“Does this look like anything to you guys?”
“Soot? Ash? Like the Witch Creek and Cedar fires.”
“Exactly. This layer – ” he pointed again to the dark band “ – is what scientists call the K-T boundary. It’s from about sixty-five million years ago. And no matter where scientists go in the world, no matter where they look for strata like this, they find this layer of ash. Because, sixty-five million years ago, the entire world was on fire.”

