Nugget Sandstone
The pale, cross-bedded eolian sandstone of the Dinosaur flanks — the northern correlative of the Navajo / Glen Canyon Group, the slickrock of Island Park and Rainbow Park.
Also known as: Nugget
Mesozoic — the age of dinosaurs
The world back then
Early Jurassic, about 195 million years ago. Same story as the Navajo, just up north — the northern reach of that giant sand sea, dunes marching across what's now Dinosaur country under a hard, dry sky. Hot days, cold nights, wind and sand and more wind. A desert wearing a different name.
Now it's the pale slickrock domes on the flanks of Dinosaur, and you drift past a desert that once seemed to have no end. Yours politely does, at a takeout, with a shuttle waiting. The luck of being the comfortable creature carried through a fossilized Sahara really doesn't get old.
Recognize it in the field
- Typical color
- pale pink to buff and white
- Weathers as
- Cliff- and slickrock-forming — smooth cross-bedded domes on the Mesozoic flanks (Island Park, Rainbow Park).
- Grain
- fine- to medium-grained, well-sorted quartz arenite
Look for
- large-scale eolian cross-bedding
- pale pink-to-buff quartz arenite
- the northern correlative of the Navajo Sandstone
- forms slickrock domes on the Dinosaur flanks
How this rock was made
The northern reach of the same Early Jurassic sand sea that laid down the Navajo across the Colorado Plateau.
The setting: wind-blown dune sea (eolian erg) (sand sea)
Up to ~2,000 ft in Wyoming; thinner across the Dinosaur flanks.
In the rock record
↑ Younger — rests above
↓ Older — sits beneath
Where to see it
Regions: Uinta Mountains / Dinosaur flanks (Middle Rocky Mountains province; NPS files Dinosaur NM under Colorado Plateaus)
- the Mesozoic slickrock flanks around Island Park and Rainbow Park (Dinosaur NM)
Float past it: Rainbow Park · Island Park · Split Mountain