Editing Silt (section)

==Occurrence==
Silt is a very common material, and it has been estimated that there are a billion trillion trillion (10<sup>33</sup>) silt grains worldwide. Silt is abundant in [[Aeolian processes|eolian]] and [[alluvial]] deposits, including [[river delta]]s, such as the [[Nile]] and [[Niger River]] deltas. [[Bangladesh]] is largely underlain by silt deposits of the [[Ganges]] delta. Silt is also abundant in northern China, central Asia, and North America.{{sfn|Assallay|Rogers|Smalley|Jefferson|1998}} However, silt is relatively uncommon in the tropical regions of the world.<ref name=Chesworth1982>{{cite journal |last1=Chesworth |first1=W. |year=1982 |title=Late Cenozoic geology and the second oldest profession |journal=Geoscience Canada |volume=9 |number=1 |url=https://journals.lib.unb.ca/index.php/GC/article/view/3288 |access-date=12 October 2021}}</ref>

Silt is commonly found in suspension in river water, and it makes up over 0.2% of river sand. It is abundant in the matrix between the larger sand grains of [[graywackes]]. Modern [[mud]] has an average silt content of 45%.{{sfn|Blatt|Middleton|Murray|1980|pp=73, 374, 381}} Silt is often found in [[mudrock]] as thin [[Lamination (geology)|laminae]], as clumps, or dispersed throughout the rock. Laminae suggest deposition in a weak current that [[Winnowing (sedimentology)|winnows]] the silt of clay, while clumps suggest an origin as [[fecal pellets]]. Where silt is dispersed throughout the mudrock, it likely was deposited by rapid processes, such as [[flocculation]].{{sfn|Potter|Maynard|Pryor|1980|pp=108-109}} [[Sedimentary rock]] composed mainly of silt is known as [[siltstone]].{{sfn|Blatt|Middleton|Murray|1980|pp=381-382}}

Silt is common throughout the [[geologic record]], but it seems to be particularly common in [[Quaternary]] formations. This may be because deposition of silt is favored by the [[glaciation]] and [[arctic]] conditions characteristic of the Quaternary.{{sfn|Assallay|Rogers|Smalley|Jefferson|1998}} Silt is sometimes known as ''[[rock flour]]'' or ''glacier meal'', especially when produced by glacial action.{{sfn|Jackson|1997|loc="rock flour"}} Silt suspended in water draining from glaciers is sometimes known as ''rock milk'' or ''moonmilk''.{{sfn|Jackson|1997|loc="rock milk"}}