Petrified Dunes is the part of Snow Canyon where the trail more or less stops being a trail. You park at the signed pullout off Snow Canyon Drive, walk a short hardpack approach, and then the path dissolves into a hundred acres of orange and ivory slickrock that you're free to wander across however you please. The "trail" distance the park lists — 1.2 miles — is a loose suggestion rather than a measured route.
What you're walking on
These aren't sand dunes. They're 180-million-year-old Navajo sandstone — Jurassic-era dune fields that lithified, got buried, and then got exhumed by the same uplift that built the Colorado Plateau. The crossbedded swirls in the rock are the original wind layering, frozen in place. Locals who've walked the slickrock at Zion or Sand Hollow recognize the same stone. At Snow Canyon it's been left exposed at human scale: low, walkable swells with shallow basins between them that pond after the rare desert rain.
How families use it
This is the easiest "real" hike in Snow Canyon and the one most St. George parents send first-time visitors to. Kids treat it as a sandstone playground — small drops, side scrambles, hidden pools — and the parking-lot-to-feature distance is short enough that nobody overheats getting there. Sunrise and sunset are the only sane summer windows; by mid-morning in July the rock surface temperature climbs past 130°F and the park literally posts heat warnings at the entrance station. October through April is when the trail is comfortable through the middle of the day.
Routefinding and ethics
There's no marked path across the rock. The park's posture is that you can walk anywhere on the slickrock but should stay off the cryptobiotic soil crust between the rock outcrops — the dark, lumpy living-soil patches that take decades to form and seconds to crush. Cairns are discouraged here; Snow Canyon's rangers knock down decorative ones because they confuse routefinding for the people coming behind. If you wander far enough to lose sight of the road, the easy navigation move is to climb the nearest dune and look for Snow Canyon Drive on the east side.
Where it sits in the park
Petrified Dunes is one of three short walks — with Whiterocks Amphitheater and Hidden Pinyon — that locals string together as a half-day Snow Canyon sampler. The trailhead sits roughly halfway between the south entrance at Ivins and the north entrance at Veyo, and the parking lot is shared with the Butterfly Trail and the lower end of the West Canyon Road network. It's one of three sandstone walks within fifteen minutes of downtown St. George that locals send out-of-towners to when the question is "show me what's actually here."