Kayenta Formation
The dark-red, ledgy river sandstone of the Glen Canyon Group — the Early Jurassic stair-step that caps and protects the Wingate cliff, printed with dinosaur tracks.
Also known as: Kayenta
Jurassic — the golden age of dinosaurs
The world back then
Early Jurassic, about 190 million years ago. A break in the desert: shifting rivers wander a dry-to-semiarid plain, carrying red and lavender silt, leaving behind ledgy channel sands and dinosaur tracks. Wetter than the dunes above and below it, but not by much — a stripe of rivers in the middle of a drought. Braided streams under a hot, big sky.
Now it's the stair-stepping ledges between the Wingate cliff and the Navajo domes, and the current carries you the whole way and asks nothing back. That old stream could barely hold its water; yours does all the work while you loaf. A comfortable float past a fossil of a drier, harder world — the trade of the century.
Recognize it in the field
- Typical color
- red, maroon, brown, and lavender
- Weathers as
- Ledge- and bench-forming — thin-bedded, stair-stepping slabs that stand back between the Wingate cliff below and the Navajo slickrock above, often armoring the Wingate.
- Grain
- fine-grained, locally coarser and well-rounded in channels
Look for
- dark-red to maroon/lavender ledgy band between two massive cliff units
- lenticular fluvial channel sandstones interbedded with siltstone
- abundant dinosaur trackways
- interfingers with the overlying Navajo Sandstone near its top
How this rock was made
Braided-to-meandering river corridors crossing a dry Early Jurassic landscape, representing wetter conditions during the advance of the Navajo dune sea.
The setting: river (fluvial) — shifting streams of fluctuating volume on an arid-to-semiarid plain
About 330–390 ft (100–120 m) typical, to ~400 ft in Glen Canyon (Wikipedia). A New Mexico Geological Society guidebook cites a wider 140–350 ft range that was not independently verified here.
In the rock record
Part of the Glen Canyon Group.
↑ Younger — rests above
↓ Older — sits beneath
Where to see it
Regions: Colorado Plateau
- Comb Ridge (type locality, Arizona)
- Capitol Reef (Waterpocket Fold)
- Zion (ledgy slopes)
- Canyonlands & Glen Canyon
- San Rafael Swell
Float past it: Westwater Canyon · Meander Canyon · Stillwater Canyon