Author Craig Childs on the Harding Icefield in Alaska.

(Sarah Gilman)

When I emailed nature writer Craig Childs recently, he sent back a perfectly characteristic reply: "I'm going to be scrambling through the desert for the next week," he wrote. "Let's find each other on the other side."

Childs is an award-winning nature writer and commentator on NPR. Most of his books have been inspired by the desert southwest, where he often explores for weeks on end. Lately, Childs has tackled bigger topics, like how the world will end, and more recently, how people came to the Americas. 

An ice camp on the Harding Icefield in south-central Alaska, where author Craig Childs scoped out ice-crossing conditions.

(Craig Childs)

He has spent the past five years traveling far from his home in Western Colorado to track humans' entry onto this continent during the Ice Age, more than 10,000 years ago. His adventures from what's left of the Bering Ice Bridge to the Florida panhandle are the basis of a book due out next year to be called "Atlas of a Lost World: Travels in Ice Age America." Childs will talk about it Thursday night at Chautauqua in Boulder

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St. Lawrence Island in the Bering Sea between Alaska and Siberia, a remnant of the Bering Land Bridge.

(Craig Childs)

A stone tool found in the Black Rock Desert in Nevada, where author Craig Childs and friends followed the terraces of an ancient Ice Age Lake.

(Craig Childs)