Moab’s desert landscape is held together by a nearly invisible living organism called biological soil crust (also known as cryptobiotic soil) — a community of fungi, lichens, cyanobacteria, and algae that takes 50+ years to develop and can be destroyed by a single footstep. This crusty, dark, bumpy surface covers virtually every square foot of undisturbed ground in canyon country, and it’s the reason Moab’s desert supports a lush pinyon-juniper forest instead of barren sand dunes. As the locals say: Don’t Bust The Crust.
What Is Biological Soil Crust?
Biological soil crust goes by several names — cryptobiotic, cryptogamic, microbiotic, or microphytic — but it all describes the same thing: living soil. The area around Moab sits on the Colorado Plateau and is almost entirely composed of sandstone. As that sandstone erodes, it creates sand. Lots of sand.
And yet Moab is not a sea of wind-swept sand dunes like the Sahara. Most of the land around Moab and throughout the surrounding canyonlands is covered in a thriving forest of pinyon pine, juniper, sage, blackbrush, yucca, rice grass, and hundreds of other species collectively called the Pinyon-Juniper Forest. In certain places and at certain times of year, it can look surprisingly green and lush for a “desert.”
The reason? Biological soil crust.
How Biological Soil Crust Works
This synergistic community of microscopic organisms performs several critical functions that make life possible in the desert:
Soil stabilization: The crust binds loose sand particles together, preventing wind erosion. Without it, the soil would simply blow away.
Moisture retention: Left undisturbed for 50 years, the crust develops into a surface of small inch-tall protrusions — like dark fingers poking up from the earth, almost mossy in appearance. This textured surface captures and retains even the slightest moisture, storing it for the plants that desperately need it.
Nitrogen fixation: Perhaps most critically, the cyanobacteria in the crust deposit nitrogen into the sand, converting what would otherwise be sterile mineral grains into fertile soil capable of supporting plant life.
In the ultra-dry environment around Moab — with average rainfall below 10 inches per year and average humidity around 20% — biological crust develops extremely slowly. That 50-year timeline is not an exaggeration. Some mature crusts may be centuries old.
Why It Matters for Visitors
Here’s the problem: if biological soil crust is disturbed — by a single tennis shoe print, a tire track, or even a dog’s paw — it is instantly crushed and reverts to loose blow sand. The 50+ years of slow biological development are erased in a fraction of a second.
With Moab now attracting well over a million visitors each year, the potential for widespread crust destruction is enormous. If everyone hiked and biked indiscriminately across undisturbed desert, canyon country would gradually transform from the lush, varied landscape you came to see into a denuded, dusty wasteland.
This is why staying on established trails is not just good etiquette in Moab — it’s ecologically critical. On every Rim Tours guided ride, our guides explain the importance of biological soil crust and ensure riders stay on designated trails. It’s one of the first things we teach.
How to Identify Biological Soil Crust
When you’re out on the trails, look for:
- Dark, bumpy surfaces between plants — the crust is usually much darker than the surrounding sand
- Small raised protrusions that look like tiny dark pinnacles or fingers
- A crusty, almost mossy texture that feels stiff to the touch
- In early stages, it may just look like darker, slightly textured sand
Once you know what to look for, you’ll see it everywhere. It’s literally in every square foot of undisturbed backcountry around Moab.
Don’t Bust The Crust: Practical Tips
- Stay on established trails at all times — this is the single most important thing you can do
- When stopping on a trail, lay your bike down with tires inside the trail edges to avoid widening the path
- Don’t create shortcuts between trail sections, even if the ground looks like “just sand”
- Watch where you walk when you step off your bike for photos or rest stops — step on rock surfaces whenever possible
- Educate your group — many visitors have never heard of biological soil crust
- On guided tours, our guides handle this naturally, pointing out crust and explaining its importance throughout the ride
Frequently Asked Questions
How long does it take for biological soil crust to recover after being damaged?
Full recovery takes 50 to 250 years, depending on the severity of disturbance and local conditions. In Moab’s extremely dry climate with less than 10 inches of annual rainfall, recovery is at the slower end of that range. A single footprint can set the clock back by half a century.
Can you walk on biological soil crust without damaging it?
No. Even a single step crushes the fragile crust structure and kills the organisms. Always stay on established trails, rock surfaces, or dry washes. If you must leave the trail, step on rocks whenever possible.
What happens to the desert if biological soil crust is destroyed?
Without crust, the soil loses its ability to retain moisture, resist wind erosion, and fix nitrogen. Plants can no longer establish and survive. The area gradually becomes barren, sandy, and prone to erosion — essentially reverting to lifeless sand dunes. This process is already visible in heavily trafficked areas around Moab.
Is biological soil crust found only in Moab?
No — biological soil crust exists across the Colorado Plateau and in arid regions worldwide. But the concentration and importance of crust in the Moab area is particularly significant because the underlying geology is almost entirely sandstone, meaning without crust, there is essentially no soil at all.
How can I help protect biological soil crust during my visit?
Stay on trails, educate yourself and your group, and consider booking a guided tour where expert guides ensure minimal impact. When stopping to take photos, step onto rock surfaces rather than soil. And spread the word — the more visitors who understand the crust, the better our chances of preserving this landscape.