To experience the “forest” of Arizona’s Petrified Forest National Park, visitors must imagine a lush tropical former world from more than 200 million years ago. In this first of two episodes, paleontologist Andrew Heckert prepares us, revealing four former worlds along the route to the park from Gallup, New Mexico. Ranger Hallie Larsen welcomes us at the park visitor center by explaining how logs turned to stone. Professor Heckert then guides us through hoodoos and badlands along the park’s Blue Mesa Loop trail.

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Podcast chapters (M= minutes, S= seconds) are summarized here:

00M 00S OPENING: I compare descending through rock layers to visiting former worlds and explain that the road from Gallup to the park is like an elevator ride into the past.

02M 26S GALLUP, LOUISIANA?: Dr. Heckert and I discuss coal-bearing layers of the Mesa Verde Group in a road cut at the edge of Gallup. He compares its former world, populated by crocodilians, scaly garfish, and horned dinosaurs, to the swamps of today’s Louisiana.

07M 36S SEAWAY & RATTLESNAKES: Outcrops seen from I-40 record the Interior Seaway that divided North America during much of the Cretaceous Period. The Mancos Shale near milepost 13 reveals offshore environments that varied over time with relative sea level. Visible near milepost 5, the Dakota Sandstone blanketed the West with river deposits as the seaway began to flood a deeply eroded landscape.

14M 38S TATOOINE AT YELLOWHORSE: At Yellowhorse Trading Post and the nearby Arizona Welcome Center, we step out of the car to gaze up at the remnants of migrating dune fields. Andy compares the Entrada Sandstone deposits to the Tunisian landscape that stood in for the desert planet Tatooine in Star Wars movies.

19M 21S LOGS TURN TO STONE: Ranger Hallie Larsen welcomes us to the park’s Painted Desert Visitor Center by explaining how giant logs in great rivers formed jams, were buried, and turned to stone. Some wood, with incomplete petrification, is less colorful but preserves cell structure.

26M 36S BLUE MESA BADLANDS: Professor Heckert looks through the images I took hiking the one-mile Blue Mesa Loop Trail, discussing hoodoos and shrink-swell clays that are a nightmare when wet. We see a petrified log that he says most likely has been “let down.”

32M 40S A CLIFF’S STORY: Andy interprets sediment layers (see podcast image) that alternate between rivers dropping sand and gravel with floodplains hosting plant roots.

39M 18S NEXT EPISODE, THANKS: I preview Episode 4 and thank participants.