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]
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 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]
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]
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]
Utopia Planitia is a large plain within Utopia, the largest recognized impact basin on Mars and in the Solar System with an estimated diameter of 3,300 km (2,100 mi). It is the Martian region where the Viking 2 lander touched down and began exploring on September 3, 1976, and the Zhurong rover touched down on May 14, 2021, as a part of the Tianwen-1 mission. It is located at the antipode of Argyre Planitia, centered at 46.7°N 117.5°E. It is also in the Casius quadrangle, Amenthes quadrangle, and the Cebrenia quadrangle of Mars.
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth. Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture and a large supply of unconsolidated sediments. Although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts.
Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. Talus deposits typically have a concave upwards form, where the maximum inclination corresponds to the angle of repose of the mean debris particle size. The exact definition of scree in the primary literature is somewhat relaxed, and it often overlaps with both talus and colluvium.
Mass wasting, also known as mass movement, is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in a moving medium, such as water, wind, or ice. Types of mass wasting include creep, solifluction, rockfalls, debris flows, and landslides, each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth, Mars, Venus, Jupiter's moon Io, and on many other bodies in the Solar System.
Gelifluction, very similar to solifluction, is the seasonal freeze-thaw action upon waterlogging topsoils which induces downslope movement. Gelifluction is prominent in periglacial regions where snow falls during six to eight months of the year. In spring, the snow and ice melt, and the landscape is effectively inundated with half a year's worth of rainfall in the space of a couple of days. The top soil becomes waterlogged, and flows like a liquid. Because the wet soil behaves like a fluid, gelifluction is a form of mass movement that can occur on slopes with a slope angle of less than half a degree.
Rock glaciers are distinctive geomorphological landforms, consisting either of angular rock debris frozen in interstitial ice, former "true" glaciers overlain by a layer of talus, or something in-between. Rock glaciers are normally found at high latitudes and/or elevations, and may extend outward and downslope from talus cones, glaciers or terminal moraines of glaciers.
Nivation is the set of geomorphic processes associated with snow patches. The primary processes are mass wasting and the freeze and thaw cycle, in which fallen snow gets compacted into firn or névé. The importance of the processes covered by the term nivation with regard to the development of periglacial landscapes has been questioned by scholars, and the use of the term is discouraged.
A periglacial lake is a lake bordering a glacier, usually found along the fringes of large ice sheets.
Patterned ground is the distinct and often symmetrical natural pattern of geometric shapes formed by the deformation of ground material in periglacial regions. It is typically found in remote regions of the Arctic, Antarctica, and the Outback in Australia, but is also found anywhere that freezing and thawing of soil alternate; patterned ground has also been observed in the hyper-arid Atacama Desert and on Mars. The geometric shapes and patterns associated with patterned ground are often mistaken as artistic human creations. The mechanism of the formation of patterned ground had long puzzled scientists but the introduction of computer-generated geological models in the past 20 years has allowed scientists to relate it to frost heaving, the expansion that occurs when wet, fine-grained, and porous soils freeze.
Astapus Colles is a group of hills in the Casius quadrangle of Mars, located at 35.5 North and 272.3 West. It is 580 km across and was named after an albedo feature at 35N, 269W. The term "Colles" is used for small hills or knobs.
Scalloped topography is common in the mid-latitudes of Mars, between 45° and 60° north and south. It is particularly prominent in the region of Utopia Planitia, in the northern hemisphere, and in the region of Peneus and Amphitrites Paterae in the southern hemisphere. Such topography consists of shallow, rimless depressions with scalloped edges, commonly referred to as "scalloped depressions" or simply "scallops". Scalloped depressions can be isolated or clustered and sometimes seem to coalesce. A typical scalloped depression displays a gentle equator-facing slope and a steeper pole-facing scarp. This topographic asymmetry is probably due to differences in insolation. Scalloped depressions are believed to form from the removal of subsurface material, possibly interstitial ice, by sublimation. This process may still be happening at present. This topography may be of great importance for future colonization of Mars because it may point to deposits of pure ice.
A frost boil, also known as mud boils, a stony earth circles, frost scars, or mud circles, are small circular mounds of fresh soil material formed by frost action and cryoturbation. They are found typically found in periglacial or alpine environments where permafrost is present, and may damage roads and other man-made structures. They are typically 1 to 3 metres in diameter.
A blockfield, felsenmeer, boulder field or stone field is a surface covered by boulder- or block-sized angular rocks usually associated with alpine and subpolar climates and periglaciation. Blockfields differ from screes and talus slope in that blockfields do not apparently originate from mass wastings. They are believed to be formed by frost weathering below the surface. An alternative theory that modern blockfields may have originated from chemical weathering that occurred in the Neogene when the climate was relatively warmer. Following this thought the blockfields would then have been reworked by periglacial action.
Glaciers, loosely defined as patches of currently or recently flowing ice, are thought to be present across large but restricted areas of the modern Martian surface, and are inferred to have been more widely distributed at times in the past. Lobate convex features on the surface known as viscous flow features and lobate debris aprons, which show the characteristics of non-Newtonian flow, are now almost unanimously regarded as true glaciers.
The Mars Reconnaissance Orbiter's HiRISE instrument has taken many images that strongly suggest that Mars has had a rich history of water-related processes. Many features of Mars appear to be created by large amounts of water. That Mars once possessed large amounts of water was confirmed by isotope studies in a study published in March 2015, by a team of scientists showing that the ice caps were highly enriched with deuterium, heavy hydrogen, by seven times as much as the Earth. This means that Mars has lost a volume of water 6.5 times what is stored in today's polar caps. The water for a time would have formed an ocean in the low-lying Mare Boreum. The amount of water could have covered the planet about 140 meters, but was probably in an ocean that in places would be almost 1 mile deep.
The landscape polewards of around 30 degrees latitude on Mars has a distinctively different appearance to that nearer the equator, and is said to have undergone terrain softening. Softened terrain lacks the sharp ridge crests seen near the equator, and is instead smoothly rounded. This rounding is thought to be caused by high concentrations of water ice in soils. The term was coined in 1986 by Steve Squyres and Michael Carr from examining imagery from the Viking missions to Mars.
In geomorphology, cryoplanation or is a term used to both describe and explain the formation of plains, terraces and pediments in periglacial environments. Uncertainty surrounds the term, and the effectiveness of the cryoplanation process is held to be limited meaning it can only produce small terraces. Instead, many of so-called cryoplanation terraces are likely an expression of the underlying lithology and rock structure rather than being unique products of cold-climate processes.
Periglaciation describes geomorphic processes that result from seasonal thawing and freezing, very often in areas of permafrost. The meltwater may refreeze in ice wedges and other structures. "Periglacial" originally suggested an environment located on the margin of past glaciers. However, freeze and thaw cycles influence landscapes also outside areas of past glaciation. Therefore, periglacial environments are anywhere when freezing and thawing modify the landscape in a significant manner.
Polygonal, patterned ground is quite common in some regions of Mars. It is commonly believed to be caused by the sublimation of ice from the ground. Sublimation is the direct change of solid ice to a gas. This is similar to what happens to dry ice on the Earth. Places on Mars that display polygonal ground may indicate where future colonists can find water ice. Low center polygons have been proposed as a marker for ground ice.
Stratified slope deposits or grèzes litées are accumulations of debris that are traditionally associated with periglaciation but that can also form in other settings. The deposits have a weak sorting and a coarse bedding. Stratified slope deposits are usually found at the lower slopes of valleys where thicknesses vary but may exceed 10 meters. Periglacial stratified slope deposits are thought to be the result of rock fragmented by frost being accumulated downslope.
