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Solifluction
Solifluction
Solifluction
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Garland-like solifluction formed in the Swiss National Park
Possible solifluction lobes in Acidalia Planitia on Mars as seen by HiRISE
Solifluction sheets near Eagle Summit, Alaska

Solifluction is a collective name for gradual processes in which a mass moves down a slope ("mass wasting") related to freeze-thaw activity. This is the standard modern meaning of solifluction, which differs from the original meaning given to it by Johan Gunnar Andersson in 1906.[1][2]

Origin and evolution of the concept

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In the original sense it meant the movement of waste saturated in water found in periglacial regions. However it was later discovered that various slow waste movements in periglacial regions did not require saturation in water, but were rather associated to freeze-thaw processes.[1][2] The term solifluction was appropriated to refer to these slow processes, and therefore excludes rapid periglacial movements.[1] In slow periglacial solifluction there are not clear gliding planes,[3] and therefore skinflows and active layer detachments are not included in the concept.[1] On the other hand, movement of waste saturated in water can occur in any humid climate, and therefore this kind of solifluction is not restricted to cold climates.[citation needed]

Slow periglacial solifluction is classified into four types:[1]

Slow solifluction acts much slower than some geochemical fluxes or than other erosion processes.[1] The relatively low rates at which solifluction operates contrast with its occurrence over wide mountain areas and periglaciated lowlands.[1][2] Since solifluction is associated with humidity and cold climates it can be used to infer past climates.[1]

Deposits

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Deposits of slow periglacial solifluction compromise poorly stratified diamicton and diamicton where stratification is wholly lacking. When stratification can be seen it is often distinguished by a buried organic soil.[3] Some other solifluction deposits that have a more defined stratification consist of alternating layers of diamicton and open-work beds, these last representing buried stone-banked lobes and sheets. A common feature in solifluction deposits is the orientation of clasts parallel to the slope.[3]

Landforms

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Solifluction lobes and sheets are types of slope failure and landforms. In solifluction lobes sediments form a tongue-shaped feature due to differential downhill flow rates.[4] In contrast, solifluction sheet sediments move more or less uniformly downslope, thus being a less selective form of erosion than solifluction lobes.[5]

  • An oblique view of lobate soil landforms in a grass-vegetated slope.
    Solifluction lobes in Wyoming
  • A photograph depicting a barren and stony mountain landscape of rounded hills. A slope seen in the background is dominated by lobate stone and soil landforms
    Solifluction lobes on a slope devoid of vegetation - Nunavut, Canada

Extraterrestrial solifluction

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It has been suggested that solifluction might be active on Mars,[6][7] even relatively recently (within the last few million years), as observed Martian lobates bear many similarities with solifluction lobes known from Svalbard.[7]

See also

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Wikimedia Commons has media related to Solifluctions.

Notes

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Notes

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References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Solifluction

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from Grokipedia
Solifluction is a periglacial geomorphic process characterized by the slow, downslope flow of water-saturated and , typically at rates of millimeters to tens of centimeters per year, occurring in environments subject to seasonal freeze-thaw cycles. This mass-wasting phenomenon primarily affects fine-textured s on gentle slopes ranging from less than 1° to 20°, where the active layer above thaws in summer, leading to excess and gravitational flow. It encompasses components such as frost creep, where individual particles move due to ice lens expansion and contraction, and gelifluction, involving the sliding of thawed sediment over underlying frozen ground. The process is most active during and summer when thawing saturates the , often forming distinctive landforms like solifluction lobes, sheets, and terraces that create step-like with of centimeters to meters. These features are common in high-latitude and high-altitude regions, including polar tundras, alpine zones, and areas influenced by past glaciations, such as deposits in and . Solifluction deposits typically consist of diamictons—unsorted mixtures of clasts in silty or sandy matrices—with clasts often oriented parallel to the or vertically at lobe fronts, reflecting the influence of and downslope transport. Key environmental controls include slope angle, which correlates positively with movement rates (e.g., 20–50 cm³ cm⁻¹ yr⁻¹ on non- slopes and up to 230 cm³ cm⁻¹ yr⁻¹ in areas), thaw depth, cover that can stabilize lobes, and the presence of excess from seasonal melting. While solifluction is a dominant slow mass-wasting process in periglacial settings, its rates and forms vary globally, with higher activity in wetter, steeper terrains like the Canadian Arctic or alpine . Understanding solifluction is crucial for assessing landscape evolution, soil stability, and hazards in cold-climate regions amid ongoing , with recent studies (as of 2024) documenting accelerated rates due to degradation and thaw subsidence.

Definition and Mechanisms

Definition

Solifluction is a periglacial mass-wasting process characterized by the slow downslope flow of water-saturated, frost-susceptible under the influence of , typically occurring at rates of 1–10 cm per year. This movement primarily affects fine-textured in cold environments where freeze-thaw cycles lead to saturation and reduced , enabling gradual soil displacement without rapid failure. Solifluction encompasses both active forms, which are ongoing in contemporary periglacial settings, and () forms, which are inactive deposits preserved from past climatic conditions. Four main types of solifluction are recognized based on temporal and environmental contexts. Active solifluction involves current downslope movement driven by seasonal or diurnal freeze-thaw processes, often producing features like turf-banked lobes in mid-latitude mountains, with measured rates such as 8.4 mm per year in or 0.4–4.3 cm per year in the Colorado Front Range. Fossil solifluction, in contrast, refers to inactive, landforms from previous periglacial episodes, such as sheet-like terraces in Niwot Ridge dated to 5,800–5,300 years , which retain diagnostic fabrics like slope-parallel clast orientations but show no modern activity. Solifluction over manifests as plug-like flow of thicker soil masses (≥60 cm deep), where the entire active layer slides over the underlying frozen ground during thaw, as observed in High-Arctic sites like the Fosheim Peninsula with active layer thaw depths of 56–65 cm. Solifluction over seasonally frozen ground, meanwhile, features shallower displacements (<60 cm) through mechanisms like annual frost creep and gelifluction, forming medium-sized lobes at rates of 1–30 cm per year, exemplified in regions like the Tien Shan mountains. Solifluction requires specific periglacial conditions to initiate and sustain movement, including mean annual temperatures below 0°C that promote ground freezing, along with the seasonal thaw of the active layer in areas or repeated freeze-thaw cycles in non- settings. These prerequisites ensure the development of excess and frost heave in frost-susceptible materials, distinguishing solifluction from other mass-wasting processes like landslides or creep in temperate zones.

Driving Mechanisms

Solifluction is primarily driven by gravitational acting on water-saturated within the active layer of periglacial environments, where the downslope component of induces deformation once the soil's resistance is overcome. This is enhanced by hydrostatic pressure generated from infiltrating the thawing active layer, which reduces and promotes downslope flow. Frost heave plays a crucial role by uplifting soil particles during freezing, creating unstable, supersaturated layers that become prone to mobilization upon subsequent thawing. Freeze-thaw cycles are central to solifluction initiation and sustenance, involving repeated seasonal and diurnal fluctuations that alter and . During freezing, migrates to the freezing front through , forming lenses and segregation lenses up to several millimeters thick within the upper active layer. These structures, often concentrated in the basal portions of the active layer, cause volumetric expansion and heave of 3–7 cm annually. Upon thawing, the melting of these lenses leads to rapid consolidation, as excess saturates the and generates high pore pressures, resulting in shear deformation and downslope flow; this process, known as thaw consolidation, can produce net surface lowering exceeding heave over multiple cycles. In a conceptual of this cycle, the vertical profile would show -rich zones forming at depth during winter, followed by a saturated, low-strength layer at the thaw front in summer, facilitating basal sliding. The saturated soil during solifluction exhibits rheological behavior akin to a Bingham fluid, characterized by a yield strength that must be exceeded by applied before flow occurs. Once the yield point is surpassed, the material flows viscoplastically with a linear stress-strain rate relationship. The downslope τ\tau driving this flow is given by τ=ρghsin⁡θ\tau = \rho g h \sin \theta where ρ\rho is the , gg is , hh is the thickness of the flowing layer, and θ\theta is the slope angle; this stress increases with layer depth and steepness until it overcomes the yield strength, typically on slopes of 5–15°. Initiation of significant solifluction requires specific thresholds, including high content sufficient for saturation and reduced , often achieved through input. Additionally, the active layer must thaw to a thickness of 0.5–2 m, allowing sufficient depth for ice segregation and subsequent consolidation to generate the necessary pore pressures for flow. These conditions are most readily met in fine-textured soils underlain by , where annual thaw penetrates ice-rich horizons.

Environmental Factors

Solifluction occurs predominantly on slopes with gradients between 5° and 15°, where gravitational forces are sufficient to drive slow mass movement without transitioning to faster landslides, though rates increase with steeper angles up to moderate inclines. In the Northern Hemisphere, north-facing aspects favor solifluction due to reduced solar insolation, cooler temperatures, and prolonged snow cover that enhances freeze-thaw cycles and moisture retention. Regolith composition plays a critical role, with fine-grained, frost-susceptible materials such as silts and clays promoting ice lens formation and soil saturation, whereas coarser substrates limit movement to superficial creep. Climatic factors strongly influence solifluction rates, particularly precipitation regimes that supply summer for saturation in periglacial settings. The presence of can stabilize slopes by restricting thaw depth or destabilize them through active layer deepening, with cold permafrost encouraging deeper, plug-like flows and warmer variants supporting shallower frost creep. Vegetation cover, such as turf or sparse , inhibits flow by binding particles and reducing diurnal freeze-thaw penetration to the uppermost layers. Substrate characteristics further modulate solifluction, including depth to , which confines movement to depths of 5-60 cm in shallow , and drainage patterns that, when impeded, enhance gelifluction through prolonged saturation. Spatially, solifluction is most prevalent in high-latitude regions like the and , as well as high-altitude alpine zones above the treeline, where periglacial conditions persist.

Historical Development

Origin of the Concept

The concept of solifluction was first introduced by Swedish geologist Johan Gunnar Andersson in his seminal 1906 paper, where he coined the term to describe the slow downslope movement of water-saturated soil and weathered material on slopes. Drawing from observations during the Swedish South Polar Expedition to the in 1901-1903, Andersson emphasized the role of saturation in forming a semifluid mass that flows gradually under , distinguishing it from faster erosional processes. He proposed the term "solifluction" (from Latin solum for soil and fluction for flow) specifically for this phenomenon, noting its prevalence in cold, humid environments where fine-grained debris becomes mobile upon thawing or wetting. Andersson's early observations linked solifluction to periglacial conditions during the Pleistocene, interpreting widespread slope deposits in as remnants of ice-age driven by saturated flows rather than glacial advance alone. In his publication, he described field evidence from northern regions, including and lobate accumulations, as products of this process interacting with fluvial erosion, providing the first systematic documentation of such features in settings. However, initial usage of the term showed some confusion with other mass-wasting events, such as mudflows or rapid debris streams, as Andersson occasionally referenced "mud-streams" in transitional contexts without strict separation. Pioneering studies by fellow Swedish geologists, such as Axel Hamberg, complemented these ideas through investigations of related frost phenomena during the 1898 Nathorst expedition to , offering foundational field evidence from on freeze-thaw dynamics and instability. Hamberg's work on glacial and periglacial features in highlighted cryogenic processes that preconditioned slopes for movement, though not explicitly termed solifluction. A key initial misconception in Andersson's formulation was the heavy emphasis on water saturation as the primary driver, with limited recognition of frost action's role in structuring and heave; this was later refined to incorporate freeze-thaw cycles as essential for modern understandings of the process.

Evolution of Understanding

In the mid-20th century, particularly during the 1940s and 1950s, periglacial geomorphology advanced through field studies in regions, where researchers like J.R. Mackay began integrating solifluction with dynamics, emphasizing its role in active-layer movements over . Mackay's early observations in the Mackenzie Delta highlighted how solifluction involved downslope flow influenced by seasonal thaw, distinguishing it from gelifluction, a frost-creep-dominant process driven by ice lens melting and soil saturation. This period marked a shift from descriptive accounts to process-oriented analyses, linking solifluction to broader stability and environmental controls like slope angle and vegetation cover. By the 1950s, theoretical models recognized solifluction as encompassing multiple components, often categorized into four primary types: needle ice creep (diurnal superficial movement), diurnal frost creep (shallow daily cycles), annual frost creep (seasonal deeper heave), and gelifluction (thaw-induced plastic flow). These distinctions, built on field measurements in regions like and , underscored varying freeze-thaw frequencies and depths as key drivers. A.L. Washburn's seminal 1973 work further classified solifluction as a dominantly flow process within periglacial environments, synthesizing observations of soil rheology and . In the , global mapping efforts compiled data from over 40 sites, revealing solifluction's prevalence in high-latitude and alpine zones, such as the Tien Shan, where the solifluction belt has a width of 900–1400 m at elevations with a lower limit of about 2500–3800 m. Debates in the and resolved earlier views limiting solifluction to saturation-driven flow, incorporating frost heave as a primary mechanism through cyclic expansion and downslope ratcheting. By the , refinements incorporated rheological models, treating saturated soils as non-Newtonian fluids to explain plug-like flows up to 60 cm deep in settings. Post-1980s advancements enabled paleoclimate reconstruction by dating relict periglacial features using cosmogenic nuclides, such as ¹⁰Be. In the , remote sensing techniques like InSAR and GPS monitoring have quantified contemporary solifluction rates (e.g., 1–10 cm/year in alpine settings) and linked them to warming, as observed in studies from the European Alps and Canadian Arctic as of the 2020s.

Terrestrial Features

Solifluction Deposits

Solifluction deposits consist primarily of poorly sorted diamictons, characterized by a mixture of clay, , , and gravel-sized clasts in a matrix-supported fabric, derived from weathered and pre-existing on slopes. These sediments exhibit high retention due to saturation from thaw-induced pore , which facilitates and results in low or absent stratification, with clasts embedded in a fine-grained, cohesive matrix often rich in organic . The internal fabric of solifluction deposits shows a preferred slope-parallel orientation of clast long axes, reflecting the downslope shear during movement. Structures include lobate fronts formed by frontal bulging and internal shear zones parallel to the slope surface, often with weakly stratified layers or folds from episodic flow. Deposit thickness generally varies from 0.5 to 3 meters, though it can reach up to 6 meters in areas of prolonged accumulation, depending on slope gradient and sediment supply. These deposits form through the progressive downslope flow and accumulation of saturated at bases, where gelifluction or plug-like flow transports material in thin sheets or lobes during seasonal thaw, building up over multiple cycles without significant sorting. They are distinguished from glacial by the absence of striated or faceted clasts, which are common in till due to abrasion, and by the presence of cracks or ice-wedge pseudomorphs indicating periglacial freeze-thaw origins rather than subglacial transport. Identification in the field relies on criteria such as undisturbed upper surfaces with intact or horizons, and the presence of buried organic layers marking episodic deposition pauses. For relict deposits, dating methods include radiocarbon analysis of incorporated from buried soils or layers, and optically stimulated (OSL) on grains to determine the last exposure age of the sediments. Micromorphological examination can further confirm oblique grain fabrics and rotated caps indicative of solifluction.

Associated Landforms

Solifluction primarily produces distinctive lobate and sheet-like landforms on slopes in periglacial environments, where saturated flows downslope due to freeze-thaw cycles above . The most prominent features are solifluction lobes, which appear as tongue- or arcuate-shaped masses with steep frontal risers typically ranging from 20° to 40° and treads that extend 5 to 50 meters in length, often with widths of 10 to 20 meters and riser heights up to 1.5 meters. These lobes form through the slow downslope movement of the active layer, creating U-, V-, or crescent-shaped fronts that advance at rates of 0.6 to 11.2 cm per year in active settings. Solifluction sheets represent broader, more uniform flows, covering areas greater than 100 meters wide and extending downslope without pronounced lobate margins, often resulting in smooth, featureless slopes in arid zones. These sheets can span hundreds of meters to kilometers in extent, with thicknesses varying from less than 0.3 meters to several meters, depending on the depth of the active layer and supply. Secondary features associated with solifluction include terraces formed by successive flow episodes, which create stepped profiles with risers indicating the depth of prior movements, often 0.5 to 2 meters high. Garlands manifest as transverse ridges perpendicular to the , typically arc-shaped and less than 10 meters wide, developing where solifluction converges around or patches. pits, small depressions 5 to 20 cm deep on lobe surfaces, arise from differential action and on exposed treads. These landforms are most common in discontinuous permafrost zones, where annual freeze-thaw cycles drive active layer deformation on slopes of 5° to 25°. Representative examples include stone-banked lobes in Ugledalen, , with movements up to 11 cm annually; turf-banked sheets and lobes near Eagle Summit, , covering areas up to several hundred meters; and extensive solifluction terraces on the southeastern , mapped over landscapes exceeding 1 km². Over time, solifluction landforms evolve from active flows during peak periglacial conditions to relict features preserved in stabilized landscapes. Relict lobes and terraces from the , dating to approximately 26,500 to 19,000 years ago, are widespread in formerly glaciated mid-latitudes, such as southern Britain and unglaciated , where they indicate past extensive and solifluction belts. In contrast, active forms persist in contemporary periglacial belts, including high and alpine regions, with ongoing deformation tied to current distribution.

Modern Observations and Implications

Contemporary Research

Contemporary research on solifluction since the 2000s has advanced through innovative monitoring techniques that capture slow surface movements with high spatiotemporal resolution. (GPS) measurements, often differential for centimeter-level precision, have been employed to track surface elevation changes over terrains, though their utility is limited for rates below 1-2 cm/year due to instrumental constraints. (InSAR), particularly Persistent Scatterer InSAR (PSInSAR) and Small Baseline Subset (SBAS) approaches using data, enables landscape-scale detection of seasonal displacements associated with active layer thaw, revealing subsidence velocities up to several millimeters per year in regions. Complementing these, (GPR) surveys at frequencies like 500-800 MHz provide subsurface imaging of anomalies such as cavities and frost penetration depths, validating InSAR findings in permafrost-adjacent areas by identifying internal structures influencing flow. (UAV)-based with image co-alignment and correlation software like COSI-Corr has emerged as a semi-automated method for site-specific monitoring, achieving resolutions of one point per square meter and detecting movements as low as 0.5 cm/year. In studies, such as those on , these combined approaches have documented typical solifluction rates of 1-5 cm/year on moderate slopes (5-10%). Recent findings from the highlight the complexity of solifluction dynamics, including transitions to more fluid-like behaviors under intensified thaw. Studies using time-series InSAR have shown that solifluction lobes often exhibit hybrid characteristics, blending slow creep with episodic surges akin to flows during rapid active layer deepening, particularly in discontinuous zones. For global inventories, platforms like and UAV-derived orthomosaics have facilitated semi-automated mapping of solifluction landforms across periglacial environments, such as in the and , enabling detection of widespread movements exceeding 2 cm/year over multi-year periods. These efforts, leveraging tools like Engine for processing large datasets, have produced high-resolution inventories that quantify solifluction coverage and variability at regional scales. Post-2022 advancements, including 2023–2025 InSAR studies, have refined detections of solifluction surges linked to extreme thaw events. Advances in numerical modeling have improved predictions of solifluction under varying thaw conditions, incorporating finite element methods (FEM) to simulate coupled thermo-hydro-mechanical processes. FEM-based simulations resolve stress-strain responses in freezing-thawing soils, accounting for frost heave and downslope flow by discretizing the active layer into elements that evolve with seasonal gradients. These models predict flow initiation and rates based on thaw depth and pore pressure buildup, with applications to predict movements under projected warming scenarios. Studies integrating outputs, such as from CMIP6, demonstrate that Arctic amplification—enhanced regional warming at 2–4 times the global average—intensifies solifluction by accelerating active layer thaw, leading to higher velocities in simulations of northern high-latitude slopes. Case studies from , , illustrate these advances in a discontinuous setting. Multi-year field surveys combined with reported solifluction velocities of 1-5 cm/year, peaking during summer thaw when active layer depths reach 50-100 cm, driven by gravitational loading on saturated tills; subsurface profiling via GPR revealed ice-rich layers contributing to episodic surges up to twice annual averages. Similarly, in , , continuous monitoring from 2002-2006 using displacement transducers and sensors on a non-permafrost slope measured surface velocities of 0.5-1.6 cm/year, with seasonal peaks during spring snowmelt-induced artesian pressures that elevated pore levels by 10-20 kPa, facilitating downslope transport rates up to 46 cm³ cm⁻¹ year⁻¹ at lobe fronts. These examples underscore the role of thaw consolidation in velocity variations, informed by integrated geophysical data.

Climate Change Impacts

Global warming is intensifying permafrost thaw, which deepens the active layer—the seasonally thawed surface soil above permafrost—thereby enhancing solifluction by increasing soil saturation and downslope mobility. Observations indicate that active layer thickness in the Northern Hemisphere has increased at an average rate of about 0.65 cm per year from 2000 to 2018, with projections suggesting further acceleration in ice-rich permafrost regions. In central Siberia, this degradation has led to a notable rise in mass movement events, including solifluction-related flows, since the early 2000s, driven by warmer ground temperatures and prolonged thaw periods. These changes amplify geohazards, particularly in infrastructure-vulnerable areas. Along the Qinghai-Tibet Railway, InSAR monitoring has detected widespread solifluction movements linked to degradation, posing risks of embankment instability and enhanced potential that threaten operational safety. Additionally, solifluction disrupts organic-rich soils, releasing stored carbon as CO₂ and , which contributes to loops exacerbating global warming; thawing alone could release 10–100 Gt of carbon by 2100 (medium confidence). Future projections aligned with IPCC assessments forecast significant expansion of solifluction-prone zones into latitudes by 2050-2100, as distribution shifts southward under RCP4.5 to RCP8.5 scenarios, potentially affecting up to 70% of infrastructure through thaw-induced instability. strategies, such as stabilization using reinforcement and drainage improvements, can reduce flow rates and erosion in high-risk areas, though widespread implementation requires adaptive engineering tailored to accelerating thaw. Socioeconomic repercussions disproportionately impact Arctic Indigenous communities, where intensified solifluction contributes to alteration, disrupting traditional , travel routes, and cultural sites. Recent studies highlight rates reaching 1 m per year in permafrost-affected coastal zones, compounding threats to and relocation needs for communities like those along the . These dynamics underscore the urgency of integrating Indigenous knowledge into resilience planning to address both ecological and human vulnerabilities.

Extraterrestrial Solifluction

Evidence on Mars

On Mars, solifluction-like processes are evidenced by lobate debris aprons (LDAs) and viscous flow features (VFFs), which exhibit flow-like morphologies extending 10-50 km from source slopes, often with convex-upward profiles and terminal ridges resembling moraines. These features are prominent in regions such as and Deuteronilus Mensae, where they mantle isolated mesas and craters, indicating slow, creep-like movement of ice-rich debris under periglacial conditions. High-resolution imaging from the camera aboard the (2006-present) reveals fresh scarps, blocky flows, and arcuate ridges on these landforms, suggesting ongoing or recent deformation, while spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and subsurface radar from SHARAD indicate ice-rich compositions with high water ice content, often exceeding 80% in buried layers beneath a thin cover. In Deuteronilus Mensae, for instance, images capture lobate extensions with sharp margins and embedded boulders, consistent with viscous flow of ice-cemented material. Crater counting analyses date the formation of LDAs and VFFs primarily to 1-10 million years ago during the Late Amazonian epoch, with low crater densities implying relatively young surfaces compared to surrounding terrains. Some features in mid-latitudes (30°-50°N) show even younger ages, potentially less than 100,000 years, based on the scarcity of small impact craters and correlations with orbital obliquity-driven ice stability changes. These Martian features bear similarities to terrestrial solifluction lobes in , where ice-rich slope flows produce comparable tongue-shaped deposits, though models propose that on Mars, seasonal CO2 frost cycles may facilitate deformation by enhancing basal lubrication or triggering instabilities in the , differing from Earth's water-driven processes.

Occurrences on Other Celestial Bodies

Solifluction-like processes have been proposed as analogs for certain geomorphic features on the , particularly in transiently shadowed regions (TSRs) near the permanently shadowed regions (PSRs) at the poles. High-resolution images from the (LRO) Narrow Angle Camera (NAC), processed using techniques, reveal slope-orthogonal lobate features in these TSRs that visually resemble terrestrial and martian solifluction lobes. These features are interpreted as potential evidence of flow over subsurface ice, facilitated by freeze-thaw cycles in the cold traps adjacent to PSRs, where temperatures remain below -200°C. Due to the 's low (approximately 1/6th of Earth's), inferred movement rates for such regolith creep are extremely slow, on the order of less than 1 mm per year, consistent with the overall low activity of lunar . On Jupiter's icy moons, flow-like terrains observed by the Galileo spacecraft suggest analogous slow-moving slushy subsurface flows that could mimic solifluction. For Europa, lobate flow-like features and chaotic terrains are attributed to the mobilization of near-surface brines or slushy ice layers, potentially driven by tidal heating and interaction with a subsurface ocean. These structures, covering regions up to hundreds of kilometers, indicate viscous deformation of the ice shell, with overlapping lobes resembling downslope soil movement on Earth. Similar interpretations apply to Enceladus, where Cassini data show smooth, resurfaced terrains possibly formed by episodic slush flows from the subsurface ocean venting through tiger stripes, though direct evidence remains limited. On Ganymede, the extensive grooved terrain, spanning much of the surface and dating to billions of years ago, has been modeled as resulting from ancient extensional tectonics involving ductile ice flow, akin to large-scale solifluction in a thicker, warmer ice layer. Beyond Jupiter's system, Saturn's moon Titan exhibits lobate deposits from methane-driven cryovolcanic flows, observed by Cassini RADAR and Visible and Mapping Spectrometer (VIMS) instruments, which bear resemblance to solifluction lobes but are propelled by hydrocarbons rather than water ice. These overlapping flow features, up to tens of kilometers wide, occur in regions like Hotei Regio and are linked to ammonia-water or methane-rich slurries erupting onto the surface. On Saturn's moon Dione, Cassini images reveal subtle lobate scarps and flow-like units potentially from past viscous creep of icy , though less pronounced than on Titan. For Mercury, the bright hollows—irregular depressions formed by the sublimation of volatile-rich minerals—are debated as possible sites of solifluction-like triggered by solar heating and volatile loss, but alternative explanations like impact vaporization dominate current models. Interpreting these extraterrestrial features faces challenges due to extreme low temperatures ranging from -100°C on Titan to -200°C on the outer moons, necessitating triggers like cryovolcanism, tidal stresses, or impacts to initiate flow in otherwise rigid ices. Models indicate that without such mechanisms, solifluction analogs would be negligible on these bodies. Studies as of 2024, including simulations previewing observations from the ESA's () mission—launched in 2023 and en route as of 2025—emphasize ice shell dynamics on Europa and Ganymede, predicting that data from flybys starting in the 2030s could confirm slushy flow contributions to lobate terrains through high-resolution and .

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