Editing Sandstone (section)

===Dott's classification scheme===
[[File:Sandstone Classification modified from Dott, 1964.jpg|thumb|Diagram showing a slightly modified version of the Dott (1964) classification scheme]]
Dott's (1964) sandstone classification scheme is one of many such schemes used by geologists for classifying sandstones. Dott's scheme is a modification of Gilbert's classification of silicate sandstones, and it incorporates R.L. Folk's dual textural and compositional maturity concepts into one classification system.<ref name="Dott">{{cite journal|title=Wacke, greywacke and matrix; what approach to immature sandstone classification?|author=Robert H. Dott|url=http://jsedres.geoscienceworld.org/content/34/3/625.abstract|year=1964 |volume=34|issue=3 |pages=625–32|doi=10.1306/74D71109-2B21-11D7-8648000102C1865D|journal=SEPM Journal of Sedimentary Research}}</ref> The philosophy behind combining Gilbert's and R. L. Folk's schemes is that it is better able to "portray the continuous nature of textural variation from mudstone to arenite and from stable to unstable grain composition".<ref name="Dott"/> Dott's classification scheme is based on the mineralogy of framework grains, and on the type of matrix present in between the framework grains.{{Citation needed|date=January 2024}}

In this specific classification scheme, Dott has set the boundary between arenite and wackes at 15% matrix. In addition, Dott also breaks up the different types of framework grains that can be present in a sandstone into three major categories: quartz, feldspar, and lithic grains.<ref name="boggs-2006-119-135"/>
* Arenites are types of sandstone that have less than 15% clay matrix in between the framework grains.
** Quartz arenites are sandstones that contain more than 90% of siliceous grains. Grains can include [[quartz]] or [[chert]] rock fragments.<ref name="boggs-2006-119-135"/> Quartz arenites are texturally mature to supermature sandstones. These pure quartz sands result from extensive [[weathering]] that occurred before and during transport. This weathering removed everything but quartz grains, the most stable [[mineral]]. They are commonly affiliated with rocks that are deposited in a stable cratonic environment, such as aeolian [[beach]]es or shelf environments.<ref name="boggs-2006-119-135"/> Quartz arenites emanate from multiple recycling of quartz grains, generally as sedimentary source rocks and less regularly as first-cycle deposits derived from primary [[igneous]] or [[metamorphic rock]]s.<ref name="boggs-2006-119-135"/>
** Feldspathic arenites are sandstones that contain less than 90% quartz, and more feldspar than unstable lithic fragments, and minor accessory minerals.<ref name="boggs-2006-119-135"/> Feldspathic sandstones are commonly immature or sub-mature.<ref name="boggs-2006-119-135"/> These sandstones occur in association with cratonic or stable shelf settings.<ref name="boggs-2006-119-135"/> Feldspathic sandstones are derived from granitic-type, primary crystalline, rocks.<ref name="boggs-2006-119-135"/> If the sandstone is dominantly plagioclase, then it is igneous in origin.<ref name="boggs-2006-119-135"/>
** Lithic arenites are characterised by generally high content of unstable lithic fragments. Examples include volcanic and metamorphic clasts, though stable clasts such as chert are common in lithic arenites.<ref name="boggs-2006-119-135"/> This type of rock contains less than 90% quartz grains and more unstable rock fragments than feldspars.<ref name="boggs-2006-119-135"/> They are commonly immature to submature texturally.<ref name="boggs-2006-119-135"/> They are associated with fluvial conglomerates and other fluvial deposits, or in deeper water marine conglomerates.<ref name="boggs-2006-119-135"/> They are formed under conditions that produce large volumes of unstable material, derived from fine-grained rocks, mostly [[shale]]s, [[volcanic rock]]s, and [[metamorphic rock]].<ref name="boggs-2006-119-135"/>
* Wackes are sandstones that contain more than 15% clay matrix between framework grains.
** Quartz wackes are uncommon because quartz arenites are texturally mature to supermature.<ref name="boggs-2006-119-135"/>
** Felspathic wackes are feldspathic sandstone that contain a matrix that is greater than 15%.<ref name="boggs-2006-119-135"/>
** Lithic wacke is a sandstone in which the matrix greater than 15%.<ref name="boggs-2006-119-135"/>
* [[Arkose]] sandstones are more than 25 percent [[feldspar]].<ref name=LF/> The grains tend to be poorly rounded and less well sorted than those of pure quartz sandstones. These feldspar-rich sandstones come from rapidly eroding [[granitic]] and metamorphic [[terrain]]s where [[chemical weathering]] is [[subordinate]] to [[physical weathering]].
* [[Greywacke]] sandstones are a [[heterogeneous]] mixture of [[Lithic Fragment (geology)|lithic fragments]] and angular grains of quartz and feldspar or grains surrounded by a fine-grained [[Clay mineral|clay]] matrix. Much of this [[Matrix (geology)|matrix]] is formed by relatively soft fragments, such as [[shale]] and some volcanic rocks, that are chemically altered and physically compacted after deep burial of the sandstone formation.