# Sediment

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Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification.

## Contents

Sediments are most often transported by water (fluvial processes), but also wind (aeolian processes) and glaciers. Beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. Glacial moraine deposits and till are ice-transported sediments.

## Classification

Sediment can be classified based on its grain size, grain shape, and composition.

### Grain size

Sediment size is measured on a log base 2 scale, called the "Phi" scale, which classifies particles by size from "colloid" to "boulder".

φ scaleSize range
(metric)
Size range
(inches)
Aggregate class
(Wentworth)
Other names
< −8> 256 mm> 10.1 in Boulder
−6 to −864–256 mm2.5–10.1 in Cobble
−5 to −632–64 mm1.26–2.5 inVery coarse gravel Pebble
−4 to −516–32 mm0.63–1.26 inCoarse gravelPebble
−3 to −48–16 mm0.31–0.63 inMedium gravelPebble
−2 to −34–8 mm0.157–0.31 inFine gravelPebble
−1 to −22–4 mm0.079–0.157 inVery fine gravel Granule
0 to −11–2 mm0.039–0.079 inVery coarse sand
1 to 00.5–1 mm0.020–0.039 inCoarse sand
2 to 10.25–0.5 mm0.010–0.020 inMedium sand
3 to 2125–250 μm 0.0049–0.010 inFine sand
4 to 362.5–125 μm0.0025–0.0049 inVery fine sand
8 to 43.9–62.5 μm0.00015–0.0025 in Silt Mud
> 8< 3.9 μm< 0.00015 in Clay Mud
> 10< 1 μm< 0.000039 in Colloid Mud

### Shape

The shape of particles can be defined in terms of three parameters. The form is the overall shape of the particle, with common descriptions being spherical, platy, or rodlike. The roundness is a measure of how sharp grain corners are. This varies from well-rounded grains with smooth corners and edges to poorly rounded grains with sharp corners and edges. Finally, surface texture describes small-scale features such as scratches, pits, or ridges on the surface of the grain. [1]

#### Form

Form (also called sphericity) is determined by measuring the size of the particle on its major axes. William C. Krumbein proposed formulas for converting these numbers to a single measure of form, [2] such as

${\displaystyle \psi _{l}={\sqrt[{3}]{\frac {D_{S}D_{I}}{D_{L}^{2}}}}}$

where ${\displaystyle D_{L}}$, ${\displaystyle D_{I}}$, and ${\displaystyle D_{S}}$ are the long, intermediate, and short axis lengths of the particle. [3] The form ${\displaystyle \psi _{l}}$ varies from 1 for a perfectly spherical particle to very small values for a platelike or rodlike particle.

An alternate measure was proposed by Sneed and Folk: [4]

${\displaystyle \psi _{p}={\sqrt[{3}]{\frac {D_{S}^{2}}{D_{L}D_{I}}}}}$

which, again, varies from 0 to 1 with increasing sphericity.

#### Roundness

Roundness describes how sharp the edges and corners of particle are. Complex mathematical formulas have been devised for its precise measurement, but these are difficult to apply, and most geologists estimate roundness from comparison charts. Common descriptive terms range from very angular to angular to subangular to subrounded to rounded to very rounded, with increasing degree of roundness. [5]

#### Surface texture

Surface texture describes the small-scale features of a grain, such as pits, fractures, ridges, and scratches. These are most commonly evaluated on quartz grains, because these retain their surface markings for long periods of time. Surface texture varies from polished to frosted, and can reveal the history of transport of the grain; for example, frosted grains are particularly characteristic of aeolian sediments, transported by wind. Evaluation of these features often requires the use of a scanning electron microscope. [6]

### Composition

Composition of sediment can be measured in terms of:

This leads to an ambiguity in which clay can be used as both a size-range and a composition (see clay minerals).

## Sediment transport

Sediment is transported based on the strength of the flow that carries it and its own size, volume, density, and shape. Stronger flows will increase the lift and drag on the particle, causing it to rise, while larger or denser particles will be more likely to fall through the flow.

### Fluvial processes: rivers, streams, and overland flow

#### Particle motion

Rivers and streams carry sediment in their flows. This sediment can be in a variety of locations within the flow, depending on the balance between the upwards velocity on the particle (drag and lift forces), and the settling velocity of the particle. These relationships are shown in the following table for the Rouse number, which is a ratio of sediment settling velocity (fall velocity) to upwards velocity. [7] [8]

${\displaystyle {\textbf {Rouse}}={\frac {\text{Settling velocity}}{\text{Upwards velocity from lift and drag}}}={\frac {w_{s}}{\kappa u_{*}}}}$

where

• ${\displaystyle w_{s}}$ is the settling velocity
• ${\displaystyle \kappa }$ is the von Kármán constant
• ${\displaystyle u_{*}}$ is the shear velocity
Mode of transportRouse number

If the upwards velocity is approximately equal to the settling velocity, sediment will be transported downstream entirely as suspended load. If the upwards velocity is much less than the settling velocity, but still high enough for the sediment to move (see Initiation of motion), it will move along the bed as bed load by rolling, sliding, and saltating (jumping up into the flow, being transported a short distance then settling again). If the upwards velocity is higher than the settling velocity, the sediment will be transported high in the flow as wash load. [9]

As there are generally a range of different particle sizes in the flow, it is common for material of different sizes to move through all areas of the flow for given stream conditions.

#### Fluvial bedforms

Sediment motion can create self-organized structures such as ripples, dunes, or antidunes on the river or stream bed. These bedforms are often preserved in sedimentary rocks and can be used to estimate the direction and magnitude of the flow that deposited the sediment.

#### Surface runoff

Overland flow can erode soil particles and transport them downslope. The erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions.

• If the initial impact of rain droplets dislodges soil, the phenomenon is called rainsplash erosion.
• If overland flow is directly responsible for sediment entrainment but does not form gullies, it is called "sheet erosion".
• If the flow and the substrate permit channelization, gullies may form; this is termed "gully erosion".

#### Key fluvial depositional environments

The major fluvial (river and stream) environments for deposition of sediments include:

### Aeolian processes: wind

Wind results in the transportation of fine sediment and the formation of sand dune fields and soils from airborne dust.

### Glacial processes

Glaciers carry a wide range of sediment sizes, and deposit it in moraines.

### Mass balance

The overall balance between sediment in transport and sediment being deposited on the bed is given by the Exner equation. This expression states that the rate of increase in bed elevation due to deposition is proportional to the amount of sediment that falls out of the flow. This equation is important in that changes in the power of the flow change the ability of the flow to carry sediment, and this is reflected in the patterns of erosion and deposition observed throughout a stream. This can be localized, and simply due to small obstacles; examples are scour holes behind boulders, where flow accelerates, and deposition on the inside of meander bends. Erosion and deposition can also be regional; erosion can occur due to dam removal and base level fall. Deposition can occur due to dam emplacement that causes the river to pool and deposit its entire load, or due to base level rise.

## Shores and shallow seas

Seas, oceans, and lakes accumulate sediment over time. The sediment can consist of terrigenous material, which originates on land, but may be deposited in either terrestrial, marine, or lacustrine (lake) environments, or of sediments (often biological) originating in the body of water. Terrigenous material is often supplied by nearby rivers and streams or reworked marine sediment (e.g. sand). In the mid-ocean, the exoskeletons of dead organisms are primarily responsible for sediment accumulation.

Deposited sediments are the source of sedimentary rocks, which can contain fossils of the inhabitants of the body of water that were, upon death, covered by accumulating sediment. Lake bed sediments that have not solidified into rock can be used to determine past climatic conditions.

### Key marine depositional environments

The major areas for deposition of sediments in the marine environment include:

• Littoral sands (e.g. beach sands, runoff river sands, coastal bars and spits, largely clastic with little faunal content)
• The continental shelf (silty clays, increasing marine faunal content).
• The shelf margin (low terrigenous supply, mostly calcareous faunal skeletons)
• The shelf slope (much more fine-grained silts and clays)
• Beds of estuaries with the resultant deposits called "bay mud".

One other depositional environment which is a mixture of fluvial and marine is the turbidite system, which is a major source of sediment to the deep sedimentary and abyssal basins as well as the deep oceanic trenches.

Any depression in a marine environment where sediments accumulate over time is known as a sediment trap.

The null point theory explains how sediment deposition undergoes a hydrodynamic sorting process within the marine environment leading to a seaward fining of sediment grain size.

## Environmental issues

### Erosion and agricultural sediment delivery to rivers

One cause of high sediment loads is slash and burn and shifting cultivation of tropical forests. When the ground surface is stripped of vegetation and then seared of all living organisms, the upper soils are vulnerable to both wind and water erosion. In a number of regions of the earth, entire sectors of a country have become erodible. For example, on the Madagascar high central plateau, which constitutes approximately ten percent of that country's land area, most of the land area is devegetated, and gullies have eroded into the underlying soil to form distinctive gulleys called lavakas . These are typically 40 meters (130 ft) wide, 80 meters (260 ft) long and 15 meters (49 ft) deep. [10] Some areas have as many as 150 lavakas/square kilometer, [11] and lavakas may account for 84% of all sediments carried off by rivers. [12] This siltation results in discoloration of rivers to a dark red brown color and leads to fish kills.

Erosion is also an issue in areas of modern farming, where the removal of native vegetation for the cultivation and harvesting of a single type of crop has left the soil unsupported. [13] Many of these regions are near rivers and drainages. Loss of soil due to erosion removes useful farmland, adds to sediment loads, and can help transport anthropogenic fertilizers into the river system, which leads to eutrophication. [14]

The Sediment Delivery Ratio (SDR) is fraction of gross erosion (interill, rill, gully and stream erosion) that is expected to be delivered to the outlet of the river. [15] The sediment transfer and deposition can be modelled with sediment distribution models such as WaTEM/SEDEM. [16] In Europe, according to WaTEM/SEDEM model estimates the Sediment Delivery Ratio is about 15%. [17]

### Coastal development and sedimentation near coral reefs

Watershed development near coral reefs is a primary cause of sediment-related coral stress. The stripping of natural vegetation in the watershed for development exposes soil to increased wind and rainfall, and as a result, can cause exposed sediment to become more susceptible to erosion and delivery to the marine environment during rainfall events. Sediment can negatively affect corals in many ways, such as by physically smothering them, abrading their surfaces, causing corals to expend energy during sediment removal, and causing algal blooms that can ultimately lead to less space on the seafloor where juvenile corals (polyps) can settle.

When sediments are introduced into the coastal regions of the ocean, the proportion of land, marine and organic-derived sediment that characterizes the seafloor near sources of sediment output is altered. In addition, because the source of sediment (i.e. land, ocean, or organically) is often correlated with how coarse or fine sediment grain sizes that characterize an area are on average, grain size distribution of sediment will shift according to relative input of land (typically fine), marine (typically coarse), and organically-derived (variable with age) sediment. These alterations in marine sediment characterize the amount of sediment that is suspended in the water column at any given time and sediment-related coral stress. [18]

### Biological considerations

In July 2020, marine biologists reported that aerobic microorganisms (mainly), in "quasi-suspended animation", were found in organically-poor sediments, up to 101.5 million years old, 250 feet below the seafloor in the South Pacific Gyre (SPG) ("the deadest spot in the ocean"), and could be the longest-living life forms ever found. [19] [20]

• Bar (river morphology)   Elevated region of sediment in a river that has been deposited by the flow
• Beach cusps   Shoreline formations made up of various grades of sediment in an arc pattern
• Biorhexistasy
• Bioswale   Landscape elements designed to manage surface runoff water
• Decantation   A process for the separation of mixtures
• Deposition (geology)   Geological process in which sediments, soil and rocks are added to a landform or landmass
• Depositional environment   Processes associated with the deposition of a particular type of sediment
• Erosion   Natural processes that remove soil and rock
• Exner equation   Law of sediment aggradation
• Grain size, also known as particle size  Diameter of individual grains of sediment, or of lithified particles in clastic rocks
• Rain dust, also known as sediment precipitation
• Regolith   A layer of loose, heterogeneous superficial deposits covering solid rock
• Sand   Granular material composed of finely divided rock and mineral particles
• Sedimentology   The study of natural sediments and of the processes by which they are formed
• Sediment trap   Any topographic depression where sediments substantially accumulate over time
• Settling   Process by which particulates settle to the bottom of a liquid and form a sediment
• Surface runoff   Flow of excess rainwater not infiltrating in the ground over its surface

## Related Research Articles

Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus. The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies. Sedimentation may also occur as dissolved minerals precipitate from water solution.

Till or glacial till is unsorted glacial sediment.

An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but are also found in more humid environments subject to intense rainfall and in areas of modern glaciation. They range in area from less than 1 square kilometer (0.4 sq mi) to almost 20,000 square kilometers (7,700 sq mi).

In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used.

Deposition is the geological process in which sediments, soil and rocks are added to a landform or landmass. Wind, ice, water, and gravity transport previously weathered surface material, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of sediment.

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.

Conglomerate is a clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel-size clasts. A conglomerate typically contain a matrix of finer grained sediments, such as sand, silt, or clay, which fills the interstices between the clasts. The clasts and matrix are typically cemented by calcium carbonate, iron oxide, silica, or hardened clay.

A turbidite is the geologic deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean.

Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to the forces acting on them: these forces can be due to gravity, centrifugal acceleration, or electromagnetism. Settling is the falling of suspended particles through the liquid, whereas sedimentation is the final result of the settling process.

Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than 116 mm and are too small to study readily in the field. At first sight, the rock types appear quite similar; however, there are important differences in composition and nomenclature.

Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Geologists use the term clastic with reference to sedimentary rocks as well as to particles in sediment transport whether in suspension or as bed load, and in sediment deposits.

An overbank is an alluvial geological deposit consisting of sediment that has been deposited on the floodplain of a river or stream by flood waters that have broken through or overtopped the banks. The sediment is carried in suspension, and because it is carried outside of the main channel, away from faster flow, the sediment is typically fine-grained. An overbank deposit usually consists primarily of fine sand, silt and clay. Overbank deposits can be beneficial because they refresh valley soils.

In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The original depositional layering is tilted, such tilting not being the result of post-depositional deformation. Cross-beds or "sets" are the groups of inclined layers, which are known as cross-strata.

In geology, a graded bed is one characterized by a systematic change in grain or clast size from one side of the bed to the other. Most commonly this takes the form of normal grading, with coarser sediments at the base, which grade upward into progressively finer ones. Such a bed is also described as fining upward. Normally graded beds generally represent depositional environments which decrease in transport energy as time passes, but these beds can also form during rapid depositional events. They are perhaps best represented in turbidite strata, where they indicate a sudden strong current that deposits heavy, coarse sediments first, with finer ones following as the current weakens. They can also form in terrestrial stream deposits.

Sediment transport is the movement of solid particles (sediment), typically due to a combination of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained. Sediment transport occurs in natural systems where the particles are clastic rocks, mud, or clay; the fluid is air, water, or ice; and the force of gravity acts to move the particles along the sloping surface on which they are resting. Sediment transport due to fluid motion occurs in rivers, oceans, lakes, seas, and other bodies of water due to currents and tides. Transport is also caused by glaciers as they flow, and on terrestrial surfaces under the influence of wind. Sediment transport due only to gravity can occur on sloping surfaces in general, including hillslopes, scarps, cliffs, and the continental shelf—continental slope boundary.

In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record. In most cases, the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the further back in geological time sediments were deposited, the more likely that direct modern analogues are not available.

The suspended load of a flow of fluid, such as a river, is the portion of its sediment uplifted by the fluid's flow in the process of sediment transportation. It is kept suspended by the fluid's turbulence. The suspended load generally consists of smaller particles, like clay, silt, and fine sands.

Sedimentary structures include all kinds of features in sediments and sedimentary rocks, formed at the time of deposition.

A bedrock river is a river that has little to no alluvium mantling the bedrock over which it flows. However, most bedrock rivers are not pure forms; they are a combination of a bedrock channel and an alluvial channel. The way one can distinguish between bedrock rivers and alluvial rivers is through the extent of sediment cover.

In hydrology stream competency, also known as stream competence, is a measure of the maximum size of particles a stream can transport. The particles are made up of grain sizes ranging from large to small and include boulders, rocks, pebbles, sand, silt, and clay. These particles make up the bed load of the stream. Stream competence was originally simplified by the “sixth-power-law,” which states the mass of a particle that can be moved is proportional to the velocity of the river raised to the sixth power. This refers to the stream bed velocity which is difficult to measure or estimate due to the many factors that cause slight variances in stream velocities.

## References

1. Boggs, Sam (2006). Principles of sedimentology and stratigraphy (4th ed.). Upper Saddle River, N.J.: Pearson Prentice Hall. p. 65. ISBN   0131547283.
2. Krumbein, Wiliam C. (1941). "Measurement and Geological Significance of Shape and Roundness of Sedimentary Particles". SEPM Journal of Sedimentary Research. 11: 64–72. doi:10.1306/D42690F3-2B26-11D7-8648000102C1865D.
3. Boggs 2006, p. 582.
4. Sneed, Edmund D.; Folk, Robert L. (March 1958). "Pebbles in the Lower Colorado River, Texas a Study in Particle Morphogenesis". The Journal of Geology. 66 (2): 114–150. Bibcode:1958JG.....66..114S. doi:10.1086/626490. S2CID   129658242.
5. Boggs 2006, pp. 66–67.
6. Boggs 2006, pp. 68–70.
7. Ali, Sk Zeeshan; Dey, Subhasish (November 2016). "Mechanics of advection of suspended particles in turbulent flow". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 472 (2195): 20160749. Bibcode:2016RSPSA.47260749A. doi:.
8. Kumbhakar, Manotosh; Ghoshal, Koeli; Singh, Vijay P. (January 2017). "Derivation of Rouse equation for sediment concentration using Shannon entropy". Physica A: Statistical Mechanics and Its Applications. 465: 494–499. Bibcode:2017PhyA..465..494K. doi:10.1016/j.physa.2016.08.068.
9. Whipple, K. X (2004). "12.163 Course Notes, MIT Open Courseware" (PDF). Retrieved 23 September 2021.
10. Sawe, Benjamin Elisha (25 April 2017). "Erosion Landforms: What Is A Lavaka?". WorldAtlas. Retrieved 24 September 2021.
11. Voarintsoa, N. R. G.; Cox, R.; Razanatseheno, M.O.M.; Rakotondrazafy, A.F.M. (1 June 2012). "Relation Between Bedrock Geology, Topography and Lavaka Distribution in Madagascar". South African Journal of Geology. 115 (2): 225–250. doi:10.2113/gssajg.115.225.
12. Cox, Rónadh; Bierman, Paul; Jungers, Matthew C.; Rakotondrazafy, A.F. Michel (July 2009). "Erosion Rates and Sediment Sources in Madagascar Inferred from 10 Be Analysis of Lavaka, Slope, and River Sediment". The Journal of Geology. 117 (4): 363–376. Bibcode:2009JG....117..363C. doi:10.1086/598945. S2CID   55543845.
13. Ketcheson, J. W. (1 March 1980). "Long-Range Effects of Intensive Cultivation and Monoculture on the Quality of Southern Ontario Soils". Canadian Journal of Soil Science. 60 (3): 403–410. doi:10.4141/cjss80-045.
14. Ohlsson, Thomas (2014). "Sustainability and Food Production". In Motarjemi, Yasmine; Lelieveld, Hubb (eds.). Food safety management: a practical guide for the food industry. Elsevier. ISBN   9780128056820 . Retrieved 24 September 2021.
15. Fernandez, C.; Wu, J. Q.; McCool, D. K.; Stöckle, C. O. (2003-05-01). "Estimating water erosion and sediment yield with GIS, RUSLE, and SEDD". Journal of Soil and Water Conservation. 58 (3): 128–136. ISSN   0022-4561.
16. Van Rompaey, Anton J. J.; Verstraeten, Gert; Van Oost, Kristof; Govers, Gerard; Poesen, Jean (2001-10-01). "Modelling mean annual sediment yield using a distributed approach". Earth Surface Processes and Landforms. 26 (11): 1221–1236. Bibcode:2001ESPL...26.1221V. doi:10.1002/esp.275. ISSN   1096-9837. S2CID   128689971.
17. Borrelli, P.; Van Oost, K.; Meusburger, K.; Alewell, C.; Lugato, E.; Panagos, P. (2018-02-01). "A step towards a holistic assessment of soil degradation in Europe: Coupling on-site erosion with sediment transfer and carbon fluxes". Environmental Research. 161: 291–298. Bibcode:2018ER....161..291B. doi:10.1016/j.envres.2017.11.009. ISSN   0013-9351. PMC  . PMID   29175727.
18. Risk, Michael J (April 2014). "Assessing the effects of sediments and nutrients on coral reefs". Current Opinion in Environmental Sustainability. 7: 108–117. doi:10.1016/j.cosust.2014.01.003.
19. Wu, Katherine J. (28 July 2020). "These Microbes May Have Survived 100 Million Years Beneath the Seafloor - Rescued from their cold, cramped and nutrient-poor homes, the bacteria awoke in the lab and grew" . Retrieved 31 July 2020.
20. Morono, Yuki; et al. (28 July 2020). "Aerobic microbial life persists in oxic marine sediment as old as 101.5 million years". Nature Communications . 11 (3626): 3626. Bibcode:2020NatCo..11.3626M. doi:10.1038/s41467-020-17330-1. PMC  . PMID   32724059.
• Prothero, Donald R.; Schwab, Fred (1996), Sedimentary Geology: An Introduction to Sedimentary Rocks and Stratigraphy, W. H. Freeman, ISBN   978-0-7167-2726-2
• Siever, Raymond (1988), , New York: Scientific American Library, ISBN   978-0-7167-5021-5
• Nichols, Gary (1999), Sedimentology & Stratigraphy, Malden, MA: Wiley-Blackwell, ISBN   978-0-632-03578-6
• Reading, H. G. (1978), Sedimentary Environments: Processes, Facies and Stratigraphy, Cambridge, Massachusetts: Blackwell Science, ISBN   978-0-632-03627-1