Deserts host a surprisingly wide range of landforms shaped by wind, sporadic water, chemical weathering, and the sheer passage of time. Sand dunes get most of the attention, but they cover only about a quarter of the world’s desert surfaces. The rest is a mix of rocky plains, dry lake beds, wind-sculpted ridges, gravel-armored pavements, steep-walled canyons, and features so unusual they were first mistaken for alien terrain when spotted on Mars. What makes desert landscapes distinctive is not one dominant process but the interplay of several, all operating in an environment where sparse vegetation and extreme aridity leave the ground exposed.
Sand Dunes and What Controls Their Shape
Sand dunes are the landform most people picture when they think of a desert, and they come in a striking variety of forms: crescent-shaped barchans, long parallel ridges called linear dunes, star-shaped dunes with arms radiating from a central peak, and massive transverse ridges. The shape a dune takes is not random. Research has shown that two factors largely determine dune type: the wind regime (how many directions the wind blows from and how often) and how much sand is available. When both of these variables are accounted for, the four basic dune types each occupy a distinct zone defined by those conditions.
Sand availability deserves special emphasis because it is often overlooked. Numerical modeling experiments have confirmed that sand supply affects not just dune shape but also dune orientation relative to the prevailing wind. For a given level of sand availability, the wind regime alone determines both shape and alignment, meaning dunes in the same region can look completely different if the local sand budget changes from one patch to another.1Scientific Reports. Phase diagrams of dune shape and orientation depending on sand availability Earlier field-based work quantified this relationship by measuring equivalent sand thickness across dune fields and correlating it with wind directional variability, establishing that the four elemental dune types arise in areas uniquely defined by both variables.2Nature. Factors determining desert dune type
Not all desert dunes are built entirely by wind acting on bare sand. In the gobi deserts of northern China, shrubs and grasses slow wind near the ground just enough to trap blowing sediment, building small mounds called nebkhas, or coppice dunes. These form throughout gravelly desert regions wherever vegetation is present, and they can grow to several meters high. Nebkhas are significant because they link biological activity to landform creation; the plant anchors the dune, and the dune in turn shelters the plant.3Sedimentology. Nebkha dune morphology in the gobi deserts of northern China and potential implications for dust emission
Wind-Carved Rock and Gravel
Wind does not just pile sand up; it also carves rock down. Two of the most distinctive wind-eroded landforms in deserts are yardangs and ventifacts, and they operate at very different scales.
Yardangs are streamlined hills or ridges, sometimes tens of meters tall, carved from bedrock or consolidated sediment by the abrasive action of wind-blown sand. Their elongated shape develops because wind and saltating grains are funneled into the troughs between ridges, concentrating erosion there while the crests remain relatively protected. Field measurements at Ocotillo Wells in California confirmed that sediment fluxes peak in the troughs, consistent with this focusing mechanism.4Journal of Geophysical Research: Earth Surface. Controls on Yardang Development and Morphology: 1. Field Observations and Measurements at Ocotillo Wells, California The material removed per sand-grain impact depends on the mechanical properties of the target rock, with softer, weaker materials eroding faster.5PubMed. Abrasion of yardangs
Ventifacts are much smaller: individual pebbles, cobbles, or boulders that have been sculpted by wind-blown sand. Their surfaces develop polished, flattened facets and sometimes deep pits or flutes. The key sign of a ventifact is uneven wear on surfaces with mixed rock hardness, because the softer parts erode faster under direct sand impact. Wind-driven sand grains do not just hit surfaces head-on; they also spiral into cavities and rebound off walls, meaning that even recessed areas get carved deeper over time.6Comptes Rendus Geoscience. Criteria for the identification of ventifacts in the geological record: A review and new insights Ventifacts in desert settings often develop thin coatings of desert varnish, a dark mineral glaze, over their abraded surfaces. These coatings can be confusing because they mask the erosion features beneath them and have historically been misidentified as something other than wind-worn rock.6Comptes Rendus Geoscience. Criteria for the identification of ventifacts in the geological record: A review and new insights
Desert Pavement
One of the most widespread yet least flashy desert landforms is desert pavement: a tightly interlocking mosaic of pebbles and stones covering the ground surface, almost like a cobblestone road laid by nature. For a long time, the standard explanation was that wind and water simply stripped away fine material, leaving the heavier stones behind as a residual lag. The reality turns out to be more interesting.
A closer look at most desert pavements in hot deserts reveals a striking feature: directly beneath the stone layer sits a thick deposit of fine, almost stone-free dust and silt that bears no resemblance to the rocky surface above it. This contrast is hard to explain by erosion alone. Instead, the prevailing model is that the rough stone surface acts as a dust trap, slowing the wind just enough for fine airborne particles to settle. When rain comes, it flushes the dust down through the gaps between stones. Over time, the accumulation of fine material beneath the stones actually pushes them upward through cycles of soil swelling and shrinking, keeping them at the surface while the underlying mantle of dust grows thicker.7Earth Surface Processes and Landforms. Desert pavements: A hidden key to Earth surface processes The result is a two-layer system that builds itself from the top down, the opposite of what most people assume.
Water-Shaped Features in a Dry Land
It sounds paradoxical, but water is one of the most powerful landscape-shaping forces in deserts. Rain is rare, yet when it falls it often arrives as intense, short-lived storms that generate flash floods. Because there is little vegetation to slow runoff and desert soils often have poor infiltration, water moves fast and carries enormous amounts of sediment.
Wadis and Dry Valleys
Wadis are the channels carved by these episodic floods. They may be bone-dry for months or years, then fill bank to bank in a matter of hours. In the Wadi Al-Sirhan catchment of northern Saudi Arabia, a region with low drainage density typical of arid landscapes, analysis found that roughly half the catchment area is highly vulnerable to soil erosion and nearly nine-tenths of it faces high to very high flash-flood risk.8Open Geosciences. Flash flood and erosion hazards in Wadi Al-Sirhan catchment, northern Saudi Arabia The severity varies sharply from one sub-catchment to another depending on slope, stream frequency, and drainage density, which is why neighboring valleys in the same desert can look so different.
Alluvial Fans and Bajadas
Where a wadi exits a mountain canyon and reaches flatter terrain, it dumps its sediment load in a fan-shaped deposit called an alluvial fan. When several fans from adjacent canyons merge along a mountain front, the combined surface is called a bajada. Studies in the Sonoran Desert near Tucson, Arizona, describe bajadas as complex mosaics of distinct geological surfaces, produced by episodes of sediment buildup separated by intervals of erosion.9Ecological Monographs. Landscape Evolution, Soil Formation, and Ecological Patterns and Processes in Sonoran Desert Bajadas Each episode leaves behind a different generation of surface material, so a single bajada can contain patches of wildly different soil age, texture, and vegetation.
Climate plays a direct role in how bajadas evolve. Work in Oman has shown that bajada sediments record a long transition from wetter conditions, when seasonal or year-round river flow could transport coarse gravel long distances, to the flash-flood-dominated regime of today’s arid climate.10Sedimentary Geology. Bajada formation by monsoonal erosion of a subaerial forebulge, Sultanate of Oman High water tables during wetter periods helped cement the gravel, making those older layers more resistant and influencing the bajada’s shape long after the rains stopped.
Playas and Salt Flats
In the lowest points of desert basins, where water collects but has no outlet to the sea, evaporation concentrates dissolved minerals into flat, dazzlingly white or pale crusts known as playas (or sabkhas in the Middle East and North Africa). These are among the flattest natural surfaces on Earth, which is why several have been used as racetracks and rocket-testing grounds.
The chemistry of a playa depends on temperature, evaporation rate, and the depth to groundwater. During hot, dry months, minerals with retrograde solubility, meaning they become less soluble as temperature rises, precipitate out. Gypsum, anhydrite, and calcite form this way. Meanwhile, evaporation near the surface concentrates other minerals like halite (common salt) in the uppermost sediment layers, provided the air is dry enough relative to the water’s salt content.11Earth-Science Reviews. Hydrogeologic processes in saline systems: playas, sabkhas, and saline lakes The result can be a complex, layered mineral crust that records seasonal and long-term climate fluctuations. Some playas hold shallow ephemeral lakes after storms that vanish within weeks, leaving behind fresh layers of salt.
Mesas, Buttes, and Badlands
Where horizontally layered rock is exposed in a desert, differential erosion creates some of the most dramatic scenery on the planet. A mesa is a flat-topped hill capped by a resistant rock layer, its sides dropping off steeply where softer rock below has been stripped away. Shrink the mesa enough and it becomes a butte, a tall, narrow remnant. The process is straightforward: a hard caprock protects the layers beneath it, but wherever the cap is breached, the softer material erodes quickly. At Jabal Al-Qarah in Saudi Arabia, the hillsides show evidence of spectacular collapses where harder overlying strata gave way after weaker material beneath was removed, eliminating the vertical support.12Geoheritage. Jabal Al-Qarah, Saudi Arabia—from a Local Tourist Spot and Cultural World Heritage to a Geoheritage Site of Possible Global Relevance
Badlands form in a related but messier way, typically in soft sedimentary rock like marl or shale. The terrain is a maze of deeply incised gullies, knife-edge ridges, and steep ravines with almost no soil or vegetation. What makes badlands in marl particularly tricky is that much of the erosion happens underground. Dispersive, sodium-rich clays swell and break apart when wet, creating subsurface pipes that can collapse into gullies. Infiltration rates change rapidly as clays swell, and surface crusts form when sodium migrates to the top layer. Large gullies with dramatic headcuts often started as collapsed subsurface pipes, and the erosion network grows by pipe capture rather than by surface runoff carving new channels.13Elsevier (CATENA). Badlands in marl lithologies: A field guide to soil dispersion, subsurface erosion and piping-origin gullies In other words, most of the sediment moving through the landscape is traveling beneath the surface, not across it.
Inverted Relief
One of the more counterintuitive features found in extremely arid deserts is inverted relief, where ancient stream channels now stand as raised ridges instead of valleys. This happens when the sediment filling a channel becomes more resistant to erosion than the surrounding material. Over time, the softer rock around the old channel wears away, leaving it perched above the landscape in positive relief.14Journal of African Earth Sciences. Inverted topography in the southeastern part of the Western Desert of Egypt
How does channel sediment become harder than its surroundings? There are several mechanisms, and they can operate independently or together. In many arid environments, wind strips fine material from old fluvial deposits, leaving a lag of coarse gravel that armors the surface against further erosion. This clast-armoring effect has been documented on a bajada in Chile’s Atacama Desert, where researchers identified inverted channels consisting of fluvial sediment deposits that resisted erosion better than the surrounding terrain.15Geomorphology. Inverted channel variations identified on a distal portion of a bajada in the central Atacama Desert, Chile Chemical cementation, where minerals precipitated by groundwater bind the channel gravel together, also contributes. These inverted channels are valuable records of ancient water flow in places that are now hyper-arid, and they have become important features in the study of Mars as well.
Volcanic Landforms Preserved by Aridity
Deserts can preserve volcanic landforms far longer than wetter environments would. Cinder cones, lava flows, and volcanic craters that would be buried under vegetation and deep soil elsewhere remain exposed and recognizable for tens of thousands of years in arid settings. The preservation is not uniform, though. A study comparing cinder cones and pahoehoe lava flows of similar age (about 12,000 years old) found dramatic differences: the cinder cone sites had developed up to a meter of continuous soil cover, while the pahoehoe flows remained largely bare, with roughly 60 percent of the surface still visibly unweathered basalt.16Elsevier (Geoderma). Controls on ecohydrologic properties in desert ecosystems: Differences in soil age and volcanic morphology Volcanic morphology matters: porous cinder weathers and develops soil more easily than dense, smooth lava.
Desert Landforms on Mars
Many of the same landforms found in Earth’s deserts show up on Mars, which has fascinated planetary scientists for decades. Dunes are the most studied example. Crescent-shaped barchan dunes and massed crescentic ridges are the most common dune types in Mars’s north polar erg and crater-floor dune fields. Early comparisons found that the plan-view shapes of Martian dunes closely resemble those found in Earth’s desert basins, and that scale ratios derived from Martian dunes at specific latitudes were nearly identical to those of gypsum dunes at White Sands, New Mexico.17Journal of Geophysical Research: Solid Earth. Morphology and distribution of common ‘sand’ dunes on Mars: Comparison with the Earth This correspondence suggests that the physics of dune formation works the same way on both planets, even though Mars requires much higher wind velocities to move sand because of its thin atmosphere.
More recent work using satellite imagery to measure thousands of individual barchan dunes has revealed some systematic differences. A study cataloguing over 2,600 Earth barchans and 720 Martian barchans found that terrestrial barchans tend to be smaller and more symmetrical, while Martian barchans more often display convergent horns that are short relative to the central body and tend to be asymmetrical.18Journal of Geophysical Research: Planets. Morphology of Barchan Dunes on Earth and Mars: Classification and Scale‐Invariance These shape differences likely reflect Mars’s distinct wind patterns, lower atmospheric density, and different sand sources. Inverted channels have also been identified on Mars, lending support to the idea that liquid water once flowed across what is now a cold, dry surface.
How Human Activity Reshapes Desert Surfaces
Desert surfaces may look barren, but many are held in place by biological soil crusts, thin layers of cyanobacteria, mosses, and lichens that bind the top few millimeters of soil. Desert pavement, as described earlier, also acts as a natural armor. When vehicles, livestock, construction, or agriculture disturb these stabilizing surfaces, the consequences can extend well beyond the disturbed patch. Damaged desert soils release dust that travels hundreds or thousands of kilometers downwind, affecting air quality, nutrient cycles, and snowmelt timing in distant mountain ranges. Disturbance to desert soil ecosystems can contribute to massive dust mobilization at regional scales.19Biodiversity and Conservation. Disturbance to desert soil ecosystems contributes to dust-mediated impacts at regional scales
Recovery is painfully slow. Desert pavement that took thousands of years to develop can be destroyed in a single off-road pass, and the accretionary dust layer beneath it, once exposed, blows away far faster than it accumulated. Biological soil crusts in some environments take decades to regrow after disturbance. This fragility is not always obvious, which is part of why deserts are sometimes treated as empty wastelands suitable for unrestricted use. The landforms themselves tell a different story: they are the product of processes playing out over millennia, and many are effectively irreplaceable on a human timescale.
Ancient Lakes Hidden Beneath the Sand
Some of the most revealing features in desert basins are not landforms you can see on today’s surface but stratigraphic layers buried beneath dunes and playa sediments. These record past lakes that once filled basins now covered by sand. In the Ulan Buh Desert of northern China, sediment cores show that the entire area was an aeolian dune environment before the Holocene, but around 7,800 years ago a paleolake appeared, covering a wide region that now includes the Jilantai Salt Lake and surrounding desert. By about 7,000 years ago, the lake began to fragment.20ScienceDirect / Elsevier. Early–middle Holocene lake-desert evolution in northern Ulan Buh Desert, China These buried lake deposits are valuable for reconstructing how climate has shifted between wet and dry phases over the past ten thousand years, and they remind us that the desert landscapes we see today are not permanent. They are snapshots of an ongoing oscillation between aridity and conditions wet enough to support large bodies of water.