Attrition (erosion)

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File:Haast River at Roaring Billy Falls.jpg|Pebbles tend to be larger upstream...

File:Haast River 14.jpg|...and decrease farther downstream...

File:Haast River 18.jpg|until they are reduced to sand and silt at the mouth.

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The amount of attrition is dependent on a number of factors: particle properties such as size, shape, surface, porosity, hardness, and cracks, as well as environmental properties such as time, velocity, pressure, shear, and temperature.Bemrose, C.R.; Bridgwater, J. (January 1987). "A review of attrition and attrition test methods". Powder Technology. 49 (2): 97–126. doi:10.1016/0032-5910(87)80054-2. ISSN 0032-5910.

Generally, particles are more affected by attrition farther downstream, as the rivers' velocity tends to be higher, and therefore its competence (ability to carry sediment) is increased. This means that the load rubs against itself more and with more force when suspended in the river, thus increasing erosion by attrition. Although there is a point after transport over a certain distance that pebbles reach a size that is relatively immune to further attrition. Grain-size distribution of sediments produced by attrition will also be controlled by the lithology of the rock from which they are derived. Particle sizes generally decrease continuously as the river flows farther downstream, in a process called downstream fining.Gomez, Basil; Rosser, Brenda J.; Peacock, David H.; Hicks, D. Murray; Palmer, Julie A. (June 2001). "Downstream fining in a rapidly aggrading gravel-bed river". Water Resources Research. 37 (6): 1813–1823. Bibcode:2001WRR....37.1813G. doi:10.1029/2001wr900007. ISSN 0043-1397. Since attrition affects pebble size it also affects the movement of the pebbles, and the size and condition of pebbles can explain past conditions of waterways, such as flow.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126.

Rates of erosion by attrition are affected by the rocks shape, lithology, and the energy of impact,Miller, K. L. and Jerolmack, D.: Controls on the rates and products of particle attrition by bed-load collisions, Earth Surf. Dynam. Discuss. [preprint], https://doi.org/10.5194/esurf-2020-86, in review, 2020. therefore, softer rocks are more susceptible to attrition erosion.Jim E. O’Connor, Joseph F. Mangano, Daniel R. Wise, Joshua R. Roering; Eroding Cascadia—Sediment and solute transport and landscape denudation in western Oregon and northwestern California. GSA Bulletin 2021; DOI: https://doi.org/10.1130/B35710.1 As attrition and breakage occur on a bedrock it becomes suspended: down-stream of a river or waterway the bedload increases due to attrition. The suspended sediment is greatly affected by lithology, basin slope, precipitation, and wildfires;Jim E. O’Connor, Joseph F. Mangano, Daniel R. Wise, Joshua R. Roering; Eroding Cascadia—Sediment and solute transport and landscape denudation in western Oregon and northwestern California. GSA Bulletin 2021; DOI: https://doi.org/10.1130/B35710.1 wildfires in general significantly disturb environments and therefore their geology.Jim E. O’Connor, Joseph F. Mangano, Daniel R. Wise, Joshua R. Roering; Eroding Cascadia—Sediment and solute transport and landscape denudation in western Oregon and northwestern California. GSA Bulletin 2021; DOI: https://doi.org/10.1130/B35710.1 Erosion rates, with respect to attrition, are greatest in waterways that are steep with soft rocks,Jim E. O’Connor, Joseph F. Mangano, Daniel R. Wise, Joshua R. Roering; Eroding Cascadia—Sediment and solute transport and landscape denudation in western Oregon and northwestern California. GSA Bulletin 2021; DOI: https://doi.org/10.1130/B35710.1 such as shale, mudstone, or other common sedimentary rocks.Assis Kanji, Milton. “Critical Issues in Soft Rocks.” ScienceDirect, vol. 6, no. 3, June 2014, pp. 186–195.

File: River Bed Attrition.png

The rounding of rocks and sand grains happens much slower in water environments than from wind.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126 This is because the water molecules around the sand protects it from collisions and because the density of water lowers the impact energy.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126. Additionally, the more irregular (compared to rounded) a sediments particle is the more it is susceptible to erosion. However, rounded particles are often the result of severe erosional environments.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126.

Differences in lithology affect how quickly erosion (attrition) changes a shoreline. It has been observed that schist rocks round quickly but then are quickly eroded away. While quartzite stays rounded for a longer time.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126. Quartzite has been found to round easily compared to schist and sandstone. Schists often erode into a flat surface under high energy attrition, not a rounded particle. Sandstone erodes to a shape between quartzite and schist. Rocks that have undergone chemical alterations, like lithification, tend to strongly resist erosion.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126.

Erosion can affect the cosmogenic exposure dating of boulders by altering the cosmogenic isotope concentration.Lim, Michael, et al. “Quantifying the Controls and Influence of Tide and Wave Impacts on Coastal Rock Cliff Erosion.” Journal of Coastal Research, vol. 27, 2011, pp. 46–56. So, by finding the cosmogenic exposure for two samples of the same rock the exposure time and rate of erosion can be found.Wood, A. “Coast Erosion at Aberystwyth; the Geological and Human Factors Involved.” Wiley Online Library, vol. 13, no. 1, Apr. 1978, pp. 61–72. The more accurate and isotope measurement is the more accurate the erosion rate or exposure time will be.

Cosmogenic exposure dating is a powerful tool in understating the process rocks undergo and can lead to a greater understanding in geomorphological studies.Wood, A. “Coast Erosion at Aberystwyth; the Geological and Human Factors Involved.” Wiley Online Library, vol. 13, no. 1, Apr. 1978, pp. 61–72.

Attrition in ocean environments is described as “the oceans consuming the land” because the high impact energy of waves and high sedimentation allow the ocean-land contact points to be significantly eroded.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126. Ocean attrition causes shorelines to retreat and ocean depths are increased to the depth of the wave base.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126.

File: Attrition Erosion, Langeland Denmark.png

The rising of sea levels has led to an increase in coastal erosion. This causes concern to policymakers, coastal researchers, and real estate planners due to erosions effect on flooding.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126.

Rocky coastlines tend to lack vegetation: this leads to little or no humic acid (organic compounds like soil). No humic acid means there is less chemical erosion, so the erosion on coastlines are almost exclusively caused by particle collisions.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126.

As ash and volcanic pyroclasts erupt from a volcano they undergo attrition.Putkonen, Jaakko, and Terry Swanson. “Accuracy of Cosmogenic Ages for MorainesJaakko.” ScienceDirect, vol. 59, no. 2, Mar. 2003, pp. 255–261. Attrition is one of the reasons why volcanic ash is very fine-grained. The more attrition erosion the more fine-grained ash produced.Putkonen, Jaakko, and Terry Swanson. “Accuracy of Cosmogenic Ages for MorainesJaakko.” ScienceDirect, vol. 59, no. 2, Mar. 2003, pp. 255–261. The consequence of this is the disruption of a volcano's geologic stability, varied tephra (rock and particles expelled from the volcano during the eruption), and more particles in the atmosphere affecting climate.Putkonen, Jaakko, and Terry Swanson. “Accuracy of Cosmogenic Ages for MorainesJaakko.” ScienceDirect, vol. 59, no. 2, Mar. 2003, pp. 255–261.

The rate of attrition on tephra is affected by the size of the volcano- specifically the depth and height of the volcanic column.Jones, T.J., Russell, J.K. Ash production by attrition in volcanic conduits and plumes. Sci Rep 7, 5538 (2017). https://doi.org/10.1038/s41598-017-05450-6

The effects of attrition can be mistaken for the effects of sorting, in which the grain size of sediments is affected by sediment transport mechanisms e.g. suspension vs. bed load. This affects pebble beaches the most as the pebbles smash into each other, which causes them to smooth.Miller, Kimberly Litwin; Szabó, Tímea; Jerolmack, Douglas J.; Domokos, Gábor (November 2014). "Quantifying the significance of abrasion and selective transport for downstream fluvial grain size evolution". Journal of Geophysical Research: Earth Surface. 119 (11): 2412–2429. Bibcode:2014JGRF..119.2412M. doi:10.1002/2014jf003156. ISSN 2169-9003.

Attrition of particulate material is also observed in the chemical industry, where it is undesirable. Products can be lost through the process and contaminants can be created, requiring additional filtration.

Attrition occurring in an industrial application stems from a wide range of mechanisms: mechanical, thermal, and chemical.Bemrose, C.R.; Bridgwater, J. (January 1987). "A review of attrition and attrition test methods". Powder Technology. 49 (2): 97–126. doi:10.1016/0032-5910(87)80054-2. ISSN 0032-5910.

In abrasive blasting, the useful life of the abrasive (sand or shot) is limited by attrition because as the workpiece surface is worn down, the abrasive breaks down as well.Bemrose, C.R.; Bridgwater, J. (January 1987). "A review of attrition and attrition test methods". Powder Technology. 49 (2): 97–126. doi:10.1016/0032-5910(87)80054-2. ISSN 0032-5910.

Attrition contributes to other types of erosion such as deflation and corrasion.Anim, Mabel, and Benjamin Kofi Nyarko. “Lithological Responses to Sea Erosion along Selected Coastlines between Komenda and Saltpond, Ghana .” Ghana Journal of Geography, vol. 9, no. 1, 2017, pp. 109–126. Although attrition is often considered a type of corrasion they differ because attrition does not move stationary surfaces and instead erodes them through transited materials.

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Category:Sedimentology

Category:Erosion