They’re selling an extreme young-earth book at the Grand Canyon explaining how it’s only a few thousand years old, and have prevented park Rangers from publishing a rebuttal of said book.

Fortunately, a rebuttal by an actual geologist is available online. That some religious kooks believe the world is 4,000 years old is one thing; they’re certainly free to do that. However, the Park Service has no business peddling this anti-science pablum from its gift shops, even along side real analysis. It lends respect to a point of view that deserves none.