The Vermilion Cliffs owe their existence to three processes separated by hundreds of millions of years: the slow accumulation of sand, mud, and silt during the Triassic and Jurassic periods; the broad tectonic uplift of the Colorado Plateau that pushed those buried sediments thousands of feet above sea level; and the relentless erosion that carved a dramatic escarpment from what had been flat-lying rock. Each step left its signature in the cliffs, from the chemistry that paints them red to the landslides that still reshape them today.
Sand Dunes on the Edge of a Supercontinent
The uppermost rock in the Vermilion Cliffs area is the Navajo Sandstone, and its origin story reads like science fiction. Around 190 million years ago, what is now the American Southwest sat near the equator on the western margin of the supercontinent Pangaea. A vast desert, sometimes compared in scale to the modern Sahara, blanketed the region with wind-blown sand that piled into enormous dunes.1Nature. Annual monsoon rains recorded by Jurassic dunes Most of that sand arrived as dry grain flows driven by winter winds, with moisture limited to brief summer episodes of rain or dew.2Trace Fossils: Concepts, Problems, Prospects. Ichnofacies of an Ancient Erg: A Climatically Influenced Trace Fossil Association in the Jurassic Navajo Sandstone, Southern Utah, USA
The resulting sand sea, known to geologists as an erg, left deposits hundreds of meters thick. You can still see the original dune structure frozen in the rock: sweeping cross-beds where sand cascaded down the slip faces of ancient dunes. These cross-bedded layers are what give formations like the Coyote Buttes their swirling, wave-like appearance. The sand was eventually buried under younger sediments, compressed, and cemented into stone by mineral-laden groundwater percolating through the pore spaces.
The Older Layers Beneath
The Navajo Sandstone caps the cliffs, but the bulk of the Vermilion Cliffs escarpment is built from older formations deposited during the Late Triassic and earliest Jurassic. At the base sits the Chinle Formation, a sequence of mudstones and shales laid down in river floodplains and shallow lakes roughly 225 to 200 million years ago. Above the Chinle lie the Moenave and Kayenta formations, recording a transition from lake and stream environments to increasingly arid conditions as the Jurassic desert expanded.
The Moenave Formation has drawn attention for what its chemistry reveals about the end-Triassic extinction, one of Earth’s five major mass extinctions. Researchers dating the formation found that the base of the thickest measured section formed around 203.7 million years ago, and the extinction interval is recorded as a sharp negative carbon-isotope shift within the middle to upper part of the sequence.3GSA Bulletin. A revised chronostratigraphy of the Triassic-Jurassic Moenave Formation, western USA: Implications for timing of continental climate change In other words, the Vermilion Cliffs contain a record of one of the most catastrophic biological crises in Earth’s history, locked inside relatively unassuming-looking mudstones.
This layered cake of rock types matters for how the cliffs look and behave. Hard sandstones form steep, vertical faces. Softer shales and mudstones erode into slopes and ledges. The Vermilion Cliffs owe their stepped, terraced profile to these contrasts in rock hardness, with resistant beds holding up cliff faces and weaker beds crumbling away beneath them.
How the Colorado Plateau Rose
Depositing the sediments was only half the story. For roughly a hundred million years after the Navajo sand sea disappeared, younger deposits buried the Vermilion Cliffs rocks under thousands of feet of additional sediment. Those layers had to be removed, and the buried rocks had to be brought up to an elevation where rivers and weather could attack them. That job fell to the Colorado Plateau’s slow, episodic rise.
Modeling of river profiles across the region shows the uplift happened in at least three major pulses. The first occurred between about 80 and 50 million years ago, generating roughly a kilometer of elevation gain at a modest pace. A second, faster phase between about 35 and 15 million years ago added approximately another 1.5 kilometers. A final phase began around 5 million years ago and continues today.4Tectonics. An uplift history of the Colorado Plateau and its surroundings from inverse modeling of longitudinal river profiles The cause of this uplift remains debated, with explanations ranging from the removal of dense rock beneath the plateau’s base to the lingering effects of ancient tectonic plate subduction. Whatever the driver, the result was a broad, flat-topped highland sitting well above sea level, with rivers now flowing steeply enough to cut deep canyons and expose buried rock layers.
As the plateau rose, rivers like the Colorado and its tributaries gained the energy to slice downward through the stacked sediments. The same uplift that made the Grand Canyon possible also exposed the rock units that form the Vermilion Cliffs. Without that elevation gain, the ancient dune sands and river muds would still be buried and invisible.
Erosion and the Grand Staircase
The Vermilion Cliffs are one step in the “Grand Staircase,” a series of cliff-and-terrace retreats that ascend northward from the Grand Canyon toward Bryce Canyon. Each step is defined by a resistant rock layer forming a cliff face, with softer rock eroding into the flat terrace below. The Chocolate Cliffs sit at the lowest level, followed by the Vermilion Cliffs, then the White Cliffs (mostly Navajo Sandstone), the Gray Cliffs, and finally the Pink Cliffs at Bryce. Early geologists mapping central Kane County, Utah, described the Vermilion Cliffs, White Cliffs, and associated landforms as conspicuous topographic features shaped by two long cycles of regional erosion punctuated by shorter periods of sediment deposition and removal.5GSA Bulletin. GEOLOGY AND GEOGRAPHY OF CENTRAL KANE COUNTY, UTAH
This staircase pattern exists because the rock layers tilt gently northward. Rivers and weathering attack the exposed edges of each resistant layer, causing the cliff face to retreat over time. Where you stand determines which “step” you see towering above you. At Lee’s Ferry along the Colorado River, you look up at the Vermilion Cliffs. Farther north, those same rocks have been eroded away and the White Cliffs dominate the skyline.
Thermochronology studies (which estimate when buried rock cooled as overlying layers were stripped away) suggest that the retreat of the Cretaceous-age “Gray Cliffs” exposed about 1.7 kilometers of rock in some areas, and subsequent retreat of the Jurassic and Triassic cliff lines removed an additional kilometer or more in places like Lees Ferry.6Geosphere. Cenozoic incision history of the Little Colorado River: Its role in carving Grand Canyon and onset of rapid incision in the past ca. 2 Ma in the Colorado River System The Vermilion Cliffs, in other words, are not static. They are a retreating cliff line, slowly migrating northward as softer rocks beneath the cliff face give way.
Landslides and the Slippery Layer at the Base
If you drive along Highway 89A beneath the Vermilion Cliffs in northern Arizona, you’ll notice the terrain at the base of the escarpment is lumpy and irregular rather than smoothly sloped. Much of this hummocky ground is actually landslide debris. Large rotational block slides mantle most of the Vermilion and Echo Cliffs escarpment, and while geologists have noted them for over a century, the mechanism was only recently studied in detail.7Environmental & Engineering Geoscience. A New Look at Landslides of the Vermilion and Echo Cliffs, Northern Arizona
The culprit is the Petrified Forest Member of the Chinle Formation, a shale layer sitting at the base of the cliff sequence. This shale contains smectite clay weathered from ancient volcanic ash. Smectite is notorious for swelling when it absorbs water and shrinking when it dries out. That repeated expansion and contraction weakens the layer, turning it into a natural slip surface. When the heavy sandstone units above lose their foundation, enormous blocks rotate and slide downhill. These are not small rockfalls. Some of the landslide blocks are massive enough to form their own ridges and valleys at the cliff base.
This process is one of the main mechanisms by which the cliff face retreats. Rather than eroding grain by grain, the Vermilion Cliffs periodically shed entire sections as the shale beneath them fails. The result is an escarpment that looks abrupt and dramatic precisely because it loses ground in sudden, large-scale events rather than through slow, uniform weathering alone.
Groundwater Sapping and Hidden Alcoves
Water also works on the cliffs from within. The Navajo Sandstone is extremely porous and acts as a natural aquifer, soaking up rainfall and snowmelt like a sponge. But that water cannot pass downward through the much less permeable formations beneath it, particularly the Kayenta Formation’s tighter siltstones. The result is a perched water table where groundwater moves laterally through the sandstone until it seeps out at the contact between the two rock units.
Where that seepage is concentrated, it undermines the sandstone from behind, dissolving cement and carrying away sand grains. Over time, this process, called groundwater sapping, carves deep alcoves and theater-headed canyons with vertical headwalls. Research in the Glen Canyon region found that groundwater sapping is the predominant mechanism forming these distinctive canyon shapes in the Navajo Sandstone, which functions as a highly transmissive aquifer sitting on essentially impermeable rock.8GSA Bulletin. Sapping processes and the development of theater-headed valley networks on the Colorado Plateau
These alcoves and spring lines are ecologically important. In an otherwise arid landscape, the seeps support hanging gardens of ferns, columbines, and mosses clinging to the damp sandstone walls. They are also the reason you’ll find narrow slot canyons and amphitheater-shaped recesses scattered throughout the Vermilion Cliffs National Monument, features that attract hikers and photographers from around the world.
Where the Red Comes From
The name “Vermilion” refers to the intense red and orange color of the cliff faces, and the pigment responsible is iron oxide, essentially rust. When iron-bearing minerals in the original sediment weathered, they released iron that was oxidized and deposited as thin coatings of hematite around individual sand grains. It takes remarkably little hematite to produce a vivid red: even a fraction of a percent by weight is enough to stain an entire outcrop.
The color varies across the escarpment. The reddest sections come from the Moenkopi and Moenave formations, where fine-grained sediment trapped iron-rich mud. The Navajo Sandstone at the top tends to be lighter, ranging from cream to pale orange, because the original dune sand was relatively clean quartz with less iron. Variations in groundwater chemistry after burial also played a role. In some places, reducing fluids (low in oxygen) bleached the red iron coatings to white or yellow, creating the dramatic color bands visible in formations like the Wave at Coyote Buttes. These bleaching patterns are secondary, meaning they formed long after the rock was deposited, as chemically distinct groundwater migrated through fractures and bedding planes.
Deformation Inside the Sandstone
Not everything inside the Navajo Sandstone is neatly cross-bedded. Scattered through the formation are zones where the original layering is thoroughly disrupted, contorted, or erased entirely. Researchers interpret many of these features as the result of liquefaction, the same process that causes sandy ground to behave like a liquid during earthquakes. In the Jurassic dune field, a shallow water table beneath the sand surface created zones of saturated sediment. When those zones were loaded unevenly by migrating dunes, the waterlogged sand could fail, with lateral spreading destroying the original bedding and creating massive, structureless sand sheets with chunks of intact bedding ripped up and carried along in the flow.9Earth Surface Processes and Landforms. Dynamic liquefaction of Jurassic sand dunes: processes, Origins, and implications
These deformation features are visible today as chaotic zones interrupting the otherwise orderly sweep of cross-beds. They tell you that the ancient desert was not uniformly bone-dry. Periods of higher water tables, fed by seasonal rains or shifting climate, left parts of the dune field vulnerable to collapse. The presence of such features in the Vermilion Cliffs area adds nuance to the common image of the Navajo as a simple pile of windblown sand.
Coeval Environments Along the Cliff Line
The landscape that produced the Vermilion Cliffs’ rock units was not one monotonous desert. Geological mapping in the region shows that coastal dune deposits, wadi (dry riverbed) sediments, and organo-sedimentary layers formed by microbial mats existed side by side during the same time interval, recording a patchwork of environments along what was then a coastline.10Geological Society of America. Back to the Jurassic: Architecture of eolian, wadi, microbialite, and disturbed facies, Carmel Formation and Navajo Sandstone, Kane County, south-central Utah Wind-blown dune sands graded laterally into flash-flood deposits in dry valleys, which in turn bordered shallow-water settings where microbial communities built layered mats. This mosaic of environments is frozen in the stratigraphy, and it means that the rock exposed in the Vermilion Cliffs varies laterally as well as vertically. Walk along the escarpment and you transition between what were once very different places on the same ancient landscape.
The “Dinosaur Dance Floor” That Wasn’t
One of the more entertaining scientific debates involving the Vermilion Cliffs concerns a site in the Coyote Buttes area informally known as the “Dinosaur Dance Floor.” The exposed surface of Navajo Sandstone there is covered in small, shallow, roughly circular depressions that were originally interpreted as the footprints of dinosaurs gathering at a water source. The name stuck and became a minor tourist draw.
A reanalysis of the site came to a different conclusion. Researchers found no direct evidence of dinosaur activity and instead interpreted the depressions as weathering pits formed on a modified surface, possibly one that had developed soil-like features while exposed between episodes of dune migration. Modern weathering and erosion then accentuated the pits, making them look more regular and footprint-like than they actually are.11PALAIOS. WEATHERING PITS VERSUS TRAMPLE MARKS: A REINTERPRETATION OF THE “DINOSAUR DANCE FLOOR”: A JURASSIC NAVAJO SANDSTONE SURFACE IN THE VERMILLION CLIFFS NATIONAL MONUMENT, ARIZONA
The episode is a useful reminder of how much interpretation goes into reading rock surfaces. Dinosaurs certainly lived in and around the Jurassic erg; genuine trackways exist elsewhere in the Navajo Sandstone. But a bumpy surface is not automatically a footprint, and the interplay of ancient soil development and modern weathering can produce features that mimic biological traces convincingly enough to fool experienced eyes for years.