The Wave, the sweeping sandstone formation tucked into the Coyote Buttes area of northern Arizona, began as sand dunes in a vast desert roughly 190 million years ago, during the Early Jurassic. Those dunes were buried, compressed into rock, uplifted thousands of feet with the Colorado Plateau, and then slowly carved by wind and water into the undulating shapes visitors line up to see today. The story is long and layered, and understanding it means looking at three distinct chapters: how the sand was deposited, how it turned to stone, and how erosion revealed the patterns hidden inside.
A Jurassic Sand Sea Bigger Than the Sahara
During the Early Jurassic, the region that is now the Colorado Plateau sat closer to the equator and was covered by an enormous sand sea, or erg, that rivaled or exceeded the modern Sahara in extent. Geologists call the resulting rock the Navajo Sandstone, and it stretches across parts of Arizona, Utah, Colorado, and Nevada. At its thickest, the formation exceeds 600 meters of nearly pure quartz sand, all deposited grain by grain as wind-driven dunes migrated across the landscape over millions of years.
The dunes were not random heaps. Prevailing winds pushed them in a broadly northeast-to-southwest direction, stacking sand in long, crescent-shaped ridges and massive compound dune fields. Seismic and well-log analyses of equivalent Jurassic formations in Wyoming confirm a dominant paleo-wind direction of approximately 225 degrees (roughly southwest), consistent with what researchers see in the Navajo Sandstone outcrops farther south.1Journal of Natural Gas Science and Engineering. Delineation of early Jurassic aged sand dunes and paleo-wind direction in southwestern Wyoming using seismic attributes, inversion, and petrophysical modeling That persistent wind direction matters because it controlled the internal architecture of the dunes, and it is that architecture you are looking at when you stand inside The Wave.
Cross-Bedding and the Internal Architecture of Dunes
If you sliced a modern sand dune in half, you would not see uniform layers. Instead, you would see angled sheets of sand that record how grains tumbled down the dune’s steep lee face, were carried along in thin curtains by the wind, or avalanched in small collapses. The Navajo Sandstone preserves all of these features in exquisite detail: tabular and wedge-shaped sets of cross-bedding, wind ripples, grainfall and grainflow deposits, avalanche layers, and zones of soft-sediment deformation where wet sand slumped before it could lithify.2Geology of the Intermountain West. The geologic glory of the Lower Jurassic Navajo Sandstone, southern Utah
Cross-bedding is the feature most responsible for The Wave’s visual drama. Each set of angled layers represents a single episode of dune migration: sand blowing up the gentle windward slope and cascading down the steep slip face. When the wind shifted or the dune surface was eroded and rebuilt, a new set of cross-beds formed at a slightly different angle. The boundaries between sets, called bounding surfaces, are where you see the sharpest contrasts in The Wave’s bands. Some layers are fine-grained and tightly packed; others are coarser and more porous. When erosion later cuts across these angled beds at a low angle, the result is the sinuous, flowing pattern that gives the formation its name. The “waves” are not ripples made by water. They are the exposed internal geometry of ancient sand dunes, sliced open and sculpted by millions of years of weathering.
From Loose Sand to Solid Rock
Sand does not become sandstone just by sitting around. After the Navajo dunes were buried under younger sediments, mineral-laden groundwater percolated through the pore spaces between grains. Over millions of years, dissolved silica and calcium carbonate precipitated as thin coatings around individual sand grains, cementing them together. This process, called lithification, turned loose quartz sand into a rock hard enough to hold steep cliffs and overhangs, yet soft enough in many spots that you can crumble it between your fingers.
The cement is not evenly distributed. Some layers received more silica and became quite hard; others retained more of their original porosity and remain comparatively weak. Zones where iron-rich fluids passed through picked up red and orange hues from iron oxide minerals like hematite and goethite, while areas flushed by reducing fluids were “bleached” to white or cream. This patchwork of cementation and coloration happened long after the dunes themselves were deposited, and it introduced a second layer of visual complexity to the rock. When you see contrasting bands of red, orange, yellow, and white sweeping through The Wave, you are seeing both the original dune architecture and the chemical fingerprint of groundwater that moved through the rock tens of millions of years later.
Uplift and Exposure
For most of the last 190 million years, the Navajo Sandstone was buried under hundreds or thousands of meters of younger rock. Starting roughly 70 million years ago, tectonic forces began pushing the Colorado Plateau upward. That uplift accelerated in fits and starts, eventually raising the plateau to its current elevation of around 1,500 to 3,000 meters above sea level. As the land rose, streams cut deeper, and the overlying rock was stripped away. By the time the landscape reached something close to its modern configuration, the Navajo Sandstone was exposed at the surface across broad swaths of southern Utah and northern Arizona, including the Coyote Buttes area where The Wave sits.
Exposure is what set the stage for the sculpting. Buried rock does not erode. But once the Navajo Sandstone was open to the sky, the combined forces of wind, rain, freezing temperatures, and biological activity began working on it. The specific shape of The Wave reflects millions of years of that ongoing interaction between rock and climate.
How Wind and Water Carved the Shape
Erosion at The Wave is not the work of a single dramatic force. It is slow, persistent, and varied. Wind carries fine sand and silt that abrades exposed surfaces, gradually rounding edges and scooping out hollows. Rainwater, though rare in this arid landscape, flows across the rock in thin sheets during storms, exploiting the weakest layers and dissolving the carbonate cement that holds some beds together. Frost wedging during cold desert nights pries grains loose from cracks. Together, these processes operate on different timescales but all contribute to the same result: the selective removal of weaker rock and the preservation of harder layers.
The key word is “selective.” Because the Navajo Sandstone is not uniform, different layers erode at different rates. A bed with strong silica cement stands proud as a ridge; the softer layer beside it is carved into a trough. When the surface being eroded cuts across cross-bedding at a shallow angle, this differential erosion traces out the sweeping, curved lines that define The Wave. The shape is not carved by any single gust or flood. It emerges from the interplay between the rock’s internal structure and the forces wearing it down.
The Role of Biological Rock Crusts
One of the less obvious factors shaping sandstone landscapes is biology. Many exposed sandstone surfaces in arid environments develop a thin, hardened rind that geologists call a biologically-initiated rock crust. This crust forms when microorganisms, including cyanobacteria and fungi, colonize the rock surface. Their metabolic byproducts and organic matter bind with mineral grains and create a shell that is dramatically tougher than the rock beneath it. Laboratory testing of these crusts on sandstone has shown them to be up to twelve times less erodible and three to thirty-five times higher in tensile strength than the soft sandstone just below the surface.3Geomorphology. Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion
This crust acts as armor. Where it is intact, the underlying sandstone is shielded from rain splash, sheet wash, and wind abrasion. Where it is breached, whether by foot traffic, freeze-thaw cycles, or simply the passage of time, the soft interior is suddenly exposed and erodes rapidly. The result is the kind of sharp-edged, sculpted topography you see at The Wave: hard-crusted fins and ridges alternating with deeply scooped troughs where the protective layer has been lost. This is part of why walking off designated paths at The Wave is so damaging. A single footstep can break through a crust that took decades or centuries to form, triggering accelerated erosion of the rock beneath. The organic component of the crust is a major contributor to its hardness; when researchers removed it with heat or enzymes, the surface strength dropped significantly.3Geomorphology. Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion
Thermal Stress and Desert Weathering
Desert sandstone faces another persistent assault that is invisible: rapid temperature swings. In arid environments, rock surfaces can heat up fast under direct sun and cool quickly once shade hits or the sun sets. These thermal cycles generate stresses at the grain scale. If the temperature changes fast enough, the outer skin of the rock expands or contracts at a different rate than the interior, and over thousands of cycles, grains loosen and flake off. High-frequency measurements in hyper-arid deserts have recorded surface temperature changes exceeding two degrees Celsius per minute for a meaningful fraction of the day, with extreme spikes reaching roughly ten degrees per minute over one-second intervals.4Geomorphology. High-frequency rock temperature data from hyper-arid desert environments in the Atacama and the Antarctic Dry Valleys and implications for rock weathering
At The Wave, where summer surface temperatures can be extreme and shade is minimal, thermal stress contributes to the gradual granular disintegration of the sandstone. The effect is subtle compared to water erosion during a flash flood, but it never stops. Every sunny day chips away at the surface, loosening individual quartz grains that the next breeze carries away. Over geological time, this slow attrition has helped smooth the undulating surfaces and round the edges of the cross-bed ridges into the organic, flowing shapes that make the formation so visually striking.
Where the Colors Come From
The Wave’s palette of reds, oranges, yellows, whites, and even purplish hues is entirely a product of iron chemistry. The Navajo Sandstone is composed almost entirely of quartz, which is colorless. The colors come from trace amounts of iron oxide minerals coating the grain surfaces. Hematite produces the deep reds and purples; goethite and limonite contribute yellows and oranges. Where iron has been removed by reducing fluids, the rock appears white or pale cream.
These color patterns did not form when the sand was first deposited. They were imposed much later, as iron-bearing groundwater migrated through the rock during burial. The fluid pathways followed zones of higher porosity and permeability, which in turn were controlled by the original dune structure. Coarser-grained avalanche layers, for instance, allowed more fluid flow than tightly packed wind-ripple layers. The result is that the color banding at The Wave roughly tracks the cross-bedding, reinforcing the visual effect of the undulating lines. In some spots, though, the color patterns cut across the bedding, creating swirling effects where fluid migration followed fractures or other secondary pathways rather than the original dune geometry.
The interplay between structural banding and chemical banding is what gives The Wave its almost painted appearance. You are simultaneously seeing the ghost of a 190-million-year-old sand dune and the record of underground water flow that happened perhaps 50 to 100 million years later. The two patterns overlap but do not perfectly align, creating a visual richness that neither would produce alone.
Why The Wave Looks Different From Its Neighbors
The Navajo Sandstone covers a vast area, so a reasonable question is why The Wave looks so distinctive when it is surrounded by cliffs and mesas made of the same rock. Several local factors converge at Coyote Buttes. The sandstone there is relatively weakly cemented compared to some nearby exposures, which allows erosion to work more aggressively and produce deeper sculpting. The particular orientation of the outcrop exposes cross-beds at just the right angle for differential erosion to trace out the flowing shapes, rather than cutting perpendicular to the beds and producing flat walls or blocky cliffs. And the semi-enclosed trough geometry of The Wave itself channels wind and occasional water flow in ways that enhance the scooping and polishing of the rock surface.
Elevation and microclimate also play a part. The Coyote Buttes area sits at a transitional elevation where freeze-thaw cycles are common in winter but intense solar heating dominates in summer. That combination maximizes the variety of weathering processes acting on the rock. A formation at lower elevation might experience less frost; one at higher elevation might be covered by soil or vegetation that shields the rock from wind abrasion. The Wave sits in a sweet spot for erosion.
How Quickly Is The Wave Changing
Geologists sometimes talk about “geological time” as if it means nothing is happening at a human scale, but sandstone erosion in arid environments is not always imperceptibly slow. Rates vary widely depending on local conditions, but weakly cemented sandstone in exposed desert settings can lose measurable amounts of surface material in decades rather than millennia. The biological crusts described earlier slow this process dramatically where they are intact, but any disturbance resets the clock. Flash floods, which occasionally funnel through the drainage where The Wave sits, can remove material in hours that took thousands of years to shape.
This is partly why access to The Wave is so tightly controlled. The Bureau of Land Management limits daily visits to a small number of permit holders. The restrictions are not just about preserving a pristine experience; they are about limiting physical damage to an actively eroding landform. Foot traffic breaks biological crusts, compresses soft surfaces, and introduces moisture from shoes. Over the decades since the formation became widely known in the 1990s, some areas of The Wave have shown visible wear along commonly walked paths. The formation will continue to evolve regardless of human activity, but unmanaged foot traffic accelerates the very erosion that created it, pushing it toward a different shape faster than natural processes would.
Fossils and Traces of Life in the Ancient Dunes
Although the Navajo Sandstone was deposited in a harsh desert environment, it was not entirely lifeless. Scattered through the formation are trace fossils, including trackways left by small reptiles and invertebrates that crossed the dune surfaces, as well as burrows made by insects or other organisms in the moist interdune areas between the major dune ridges. These traces tell geologists that the Jurassic erg, while dominated by barren sand, had oases and wet interdune flats where life could survive, at least intermittently.
At The Wave itself, visible trace fossils are not a major feature, but they do appear in the broader Coyote Buttes area and in Navajo Sandstone exposures throughout southern Utah. The presence of these traces influenced the cementation of the rock in subtle ways: organic material from burrows and microbial mats created localized chemical environments that affected how minerals precipitated. In some cases, ancient burrows are now harder or softer than the surrounding rock and stand out as bumps or pits on eroded surfaces, adding another layer of texture to the sculpted landscape.
The interdune deposits are often recognizable as thin, flat-bedded layers of finer sediment between the massive cross-bedded dune sets. At The Wave, some of the sharp horizontal breaks between sets of sweeping cross-beds may represent these interdune surfaces, where the sand was briefly stabilized by moisture or vegetation before the next dune rolled over it. These breaks are among the most prominent visual features, creating the horizontal “pauses” between the flowing bands that give the formation its rhythmic appearance.