Until then fundamentalists had mostly avoided any close study of geology, because a literal reading of the Bible was too difficult to reconcile with the accepted age of the earth. But “The Genesis Flood” served as their version of “The Feminine Mystique,” a generational manifesto that liberated them to explore. In the decades since, a small band of geologists, including Whitmore, have set to work improving on the Morris-Whitcomb model using the modern tools of their field: close examination of rocks and fossils combined with computer models.

Now the movement can count hundreds of scientists with master’s or Ph.D. degrees in the sciences from respectable universities. The change started in part when Christian colleges that used to resist mainstream science started premed programs, which meant they needed trained biologists and chemists. Eventually they added courses in physics, chemistry and geology. Most geologists teaching at Christian colleges in the United States today say they do not believe in a young earth; they typically argue that a “day” in Genesis does not necessarily mean a literal 24-hour day, or that there could have been long gaps between the days. But the young-earthers treat the words of Genesis as irrefutable fact.

Image Rock and mineral specimens from a geology lab at Cedarville University. Credit... Brian Ulrich

Their ideas are being showcased in the new Creation Museum in Petersburg, Ky., opened in May by a creationist group called Answers in Genesis, whose headquarters are nearby. With its wide-open spaces and interactive exhibits, the place feels like a slick museum of natural history, updated for the Hollywood age. Many of the exhibits were designed by Patrick Marsh, who helped create the “Jaws” and “King Kong” attractions at Universal Studios in Florida. Giant dinosaurs guard the courtyard entrance, promising fun and adventure. Inside, a replica of the ark leads you from seaboard to bottom deck, a rumbling theater replicates the flood, James Cameron-style. Lifelike models of Adam and Eve (who looks like the Brazilian supermodel Gisele Bündchen) frolic in a lush garden among the animals, including several dinosaurs.

The museum expected about 250,000 visitors in the first year. Instead, despite its $20 entry fee, it has had that many in six months, according to Michael Matthews, the museum’s content manager. Almost every day, minivans and buses from Christian schools fill the parking lot, sometimes after 10-hour road trips. The museum’s target group is the 45 percent of Americans who, for 25 years, have consistently agreed with the statement in a Gallup poll that “God created human beings pretty much in their present form at one time within the last 10,000 years or so.”

The museum sends the message that belief in a young earth is the only way to salvation. The failure to understand Genesis is literally “undermining the entire word of God,” Ken Ham, the founder of Answers in Genesis, says in a video. The collapse of Christianity believed to result from that failure is drawn out in a series of exhibits: school shootings, gay marriage, drugs, porn and pregnant teens. At the same time, it presents biblical literalism as perfectly defensible science. A fossil shows a perch eating a herring, evidence, they claim, of animals instantaneously trapped by catastrophic events after the flood. In a video, geologists use evidence from Mount St. Helens to show how a mud flow can cut a deep canyon in a single day. “This is what I see based on science,” said Andrew Snelling, one of the many creationist geologists at the conference in July who consulted with the museum.

At the conference, participants got together to tackle some difficult questions: How is radioisotope dating flawed? How was the Grand Canyon formed? If all those animals died in one cataclysmic event, why do their fossils appear in such distinct order? Their discussions recall a pre-Darwinian age, before science and faith became enemies. The old-earthers see their discipline as more pure than intelligent design; the intelligent-design people focus on a notion of a mystery “designer,” without specifying who that might be and what the mechanisms are. To the young-earth creationists, this is both unscientific and dubiously religious. “We don’t subscribe to this idea of the ‘God of gaps,’ meaning if you can’t explain something, then blame God,” Whitmore told me before describing a method that hardly seemed more scientific. “Instead, we think: ‘Here’s what the Bible says. Now let’s go to the rocks and see if we find the evidence for it.’ ”