Sub Aerial Processes

What is Sub Aerial Process?

Sub-aerial procedures additionally help the pace of erosion of coasts. Sub-aerial procedures allude to the procedures of weathering and mass development. Weathering is the separating of rock in situ. It tends to be separated into mechanical and synthetic weathering. Mechanical weathering alludes to physical procedures like freeze-defrost activity and organic weathering. Freeze-defrost weathering splits up rock as water freezes in breaks. The ice applies to weight and breaks the stone. Organic weathering is brought about by the underlying foundations of vegetation and settling winged animals. A progressively regular sort of mechanical weathering found at coasts is salt crystallization. This happens as waves store salt crystals in splits, and after some time, the salt like ice applies strain to the break. Concoction weathering happens because of a powerless compound response among water and rock—e.g. with limestone. Carbonic corrosive, formed from rainwater and carbon dioxide, will respond with calcium carbonate in limestone to form calcium bicarbonate. Since calcium bicarbonate is dissolvable in water, the limestone adequately gets endured when carbonation happens. The job of weathering is to debilitate precipices. This debilitating velocity increases the pace of erosion. Another sub-aerial procedure is mass development. A mass development alludes to the development of material downslope affected by gravity. They can be fast occasions, landslides and rockfalls or they can be reasonable procedures, for example, soil creep. A typical sort of mass development at coasts is rotational droops. Droops happen because of a mix of components. Marine procedures dissolve and undermine the base of the cliff. This evacuates the help of the cliff.

What is more, precipitation penetrates the slant through unconsolidated permeable material and afterward makes a slip plane as it arrives at an impermeable material, for example, dirt. The mud and aggregating water empower the weighted immersed material above to droop. This procedure can be found in the outline underneath. 

Tides are brought about by the gravitational draw of the moon and, to a lesser degree, the sun. Tides are a significant factor in thinking about coastal procedures, as their association with the coastal environment, to an enormous degree, decides the area of numerous coastal landforms. Feeble tidal flows and a small tidal range will decide the shape and degree of stream deltas just as the size of beach profiles. The degree of the tidal range will likewise impact the paces of erosion found at precipices. There are two significant tides to observe; the Spring tide and the Neap tide. The Springtide forms twice in the lunar cycle and builds the tidal range by elevating the elevated tide imprint and bringing down the low tide mark. This is brought about by the arrangement of the moon and sun, which adjusts their gravitational draw. The Neap tide delivers a low tidal range, in that the higher tide is lower than ordinary and low tide more elevated. This again happens twice in the lunar cycle because of the sun and moon acting against one another. 

Sub-Aerial Processes 

The sub-aerial procedure is land-based procedures that adjust the state of the coastline. These are a mix of weathering and mass development. 

Sub-aerial procedures – weathering 

Weathering is the rot and crumbling of rock in situ. There are two primary kinds of weathering that influence the coast. These are mechanical and organic weathering. 

Mechanical (physical) weathering 

Mechanical or physical weathering is the crack and breakdown of rocks into sections. Along the coast, it might be brought about by icebreaking (freeze-defrost), salt crystallization, wetting and drying, or even naturally. 

Mechanical weathering alludes to physical procedures, for example, freeze-defrost and natural weathering. Freeze-defrost happens when water gets into breaks in rocks and freezes. This, at that point, grows by around 10%. The rehashed freeze-defrost activity squeezes the stones until they inevitably split and break the stone. Freeze-defrost, for the most part, happens when the temperature wavers around the point of solidification. The broke precise pieces of rock collect around the base of the cliff as scree (bone). As coastal atmospheres will, in general, be milder, this procedure is just extremely compelling during freezing winters. 

Freeze-defrost weathering 

A typical kind of mechanical weathering found at coasts is salt crystallization. This is when precious salt stones are kept in splits and, after some time, the salt amasses and applies strain to the break (like freeze-defrost weathering). 

Wetting and drying are regular along coastlines. Mud rich rocks are inclined to grow when they are wet and agreement when they dry—this outcome in splits which are defenseless against both freeze-defrost and salt crystallization. 

Organic weathering is mechanical when there is a physical impact. A case of this is when developing plant roots enlarge breaks, as does the influence made by shrubs and trees influencing in strong breezes. Tunnelling creatures and settling fowls exhume material in incompletely endured and dissolved precipices. 

Substance weathering 

Substance weathering include decay of rocks (truly, changing the minerals). Concoction weathering happens because of a powerless substance response among water and rock. E.g. with limestone. Rainwater blended in with carbon dioxide in the climate forms Carbonic corrosive. This, at that point, responds with calcium carbonate in limestone to form calcium bicarbonate. Bicarbonate is dissolvable in water, and the limestone gets endured when carbonation happens. 

The job of weathering is to debilitate precipices. This debilitating paces up the paces of erosion. 

Sub-aerial procedures – mass development 

Mass development is the development of material downslope as a consequence of gravity. This can be a reasonable procedure on account of soil creep or quick on account of rockfalls. Water usually goes about as an ointment in mass development. 

Soil Creep 

Soil creep a reasonable, however ceaseless procedure. It commonly happens on most inclines more than 5 degrees. Soil creep once in a while surpasses velocities of 1cm every year. Creep happens as the aftereffect of rehashed development and compression of the material. Patterns of freeze-defrost hurl particles after freezing and permit them to fall further downslope when the ice liquefies. Rotating hydration and drying out have a similar impact. 

Earth streams 

Earth streams will, in general, be quicker than moderate jerk yet less sporadic. Earth flows have a trademark “hourglass” shape. The slant material melts and runs out, forming a bowl or despondency at the head. The stream itself is lengthened and, for the most part, happens in fine-grained materials or mud bearing rocks on moderate slants and under immersed conditions. Be that as it may, dry progressions of granular material are additionally conceivable. 

Land Slide 

This is the downslope development of an enormous square of material that moves as a rational mass. This implies it holds its inward structure until hitting the base of the slant and breaking into little pieces. It is progressively typical over wet periods, on soak slants, and frequently happens on coastlines. 

A land slide at Port Mulgrave, Yorkshire and Cleveland Heritage Coast. 


A mudflow is an earthflow comprising of material that is sufficiently wet to stream quickly, and that contains in any event 50 percent sand, sediment, and dirt estimated particles. In some instances, for instance, in numerous paper reports, mudflows and flotsam and jetsam streams are usually alluded to as “landslides.” 


One of the most widely recognized kinds of mass development along the coast is rotational droops. 

Droops happen on account of various elements. Initially, marine procedures disintegrate and undermine the base of the precipice. Rainwater penetrates the precipice through unconsolidated, permeable material (for example, stone mud). This, at that point, makes a slip plane. The heaviness of the immersed dirt makes the material droop along the slip plane. The procedure is represented in the graph beneath. 


Rockfalls usually are connected with vertical inclines. Just increasingly safe stone can continue these points on the coast. They are most regularly activated by undermining in the between tidal zone or freeze-defrost weathering. 


Run-off can move excellent material downslope, especially where the overland stream happens as a thin, persistent layer (sheet stream) and washes sediment and mud estimated particles.


Sub-aerial procedures are land-based procedures that modify the state of a coastline. They are a mix of both weathering and mass development. 



Freeze defrost weathering includes water entering breaks in rocks and freezing. At the point when the water freezes, it grows, cracking the stone. 


The rehashed activity of warming and cooling rocks, making them “shed” off layers. 

Natural Weathering 

Plant seeds get into splits in rocks and start developing. As they develop, they apply pressure on the rocks, making them crack. Ocean growth, under the ocean, can join itself to rocks so that, as the ocean moves the kelp, pieces of rock are pulled away. 

Substance Weathering 

Consumption is, in fact, a form of weathering and not erosion. Procedures, for example, hydrolysis and oxidation, can climate away shakes. Hydrolysis includes the parting of minerals because of their reactivity with water. Oxidation is, essentially, rusting. Components, for example, iron, are powerless to oxidation and can be found inside minerals on coastlines. 

Mass Movement 

Mass development can be characterized as the vast scope development of endured material because of gravity. It is the point at which a cliff or other structure that is not evenly orientated has been endured to where it begins to crumble. There are five sorts of mass development: rockfall, soil creep, landslides, mudflow and drooping. 


Freeze defrost weathering on a cliff splits the stones up into little pieces, which would then be able to free fall. This happens regularly on cliffs with bunches of joints as the joints make it simpler to separate the stone. On the off chance that the ocean undermines the cliff, it can free a portion of its steadiness, improving the probability that a rockfall will happen. 

Soil Creep 

Soil creep an extraordinarily reasonable procedure. It happens on delicate inclines and delivers an undulated (wavy) surface. Clammy soil moves gradually downslope because of the expansion in its mass (since it is wet). 


In the wake of being drenched by water, cliffs produced using soft stone will start to slip because of the stone being greased up. Landslides are fundamentally the same as droops. 

(Rotational) Slumping 

Drooping occurs for comparative motivations to landslides. Substantial precipitation makes the stone heavier because of it retaining the water, and the water additionally goes about as an ointment. The distinction with drooping is that it occurs on a curved surface, which makes the precipice form a sickle shape. 


A mudflow is a hazardous form of mass development that happens on soak inclines with immersed soil and little vegetation. The absence of vegetation implies that there is nothing to tie the dirt together, advancing mass squandering. The wet soil gets more massive and is greased up, prompting the fast development of a ton of mud downhill.


  • Coastal Processes. (n.d.). Retrieved from British Geographer:
  • Sub-Aerial Processes. (n.d.). Retrieved from Geography AS Notes:
  • Sub-Aerial Processes. (n.d.). Retrieved from A Level Geography:
  • Subaerial processes and types of mass movement . (n.d.). Retrieved from Prezi:
  • Sub-Aerial Processes Flashcards Preview . (n.d.). Retrieved from Brainscape:

Cite/Link to This Article

  • "Sub Aerial Processes". Geography Revision. Accessed on March 3, 2021.

  • "Sub Aerial Processes". Geography Revision, Accessed 3 March, 2021.

  • Sub Aerial Processes. Geography Revision. Retrieved from