page_title: Sedimentary rock
section_title: Sandstones
hierarchical_section_title: Sedimentary rock / Classification based on origin / Clastic sedimentary rocks / Sandstones
caption_attribution_description: Deutsch: Sedimentgesteine auf Malta
context_page_description: Sedimentary rocks are types of rock that are formed by the accumulation or deposition of small particles and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. 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 or biological detritus. Before being deposited, the geological detritus was formed by weathering and erosion from the source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers, 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.
  The sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust.
context_section_description: Sandstone classification schemes vary widely, but most geologists have adopted the Dott scheme, which uses the relative abundance of quartz, feldspar, and lithic framework grains and the abundance of a muddy matrix between the larger grains.
  Composition of framework grains
  The relative abundance of sand-sized framework grains determines the first word in a sandstone name. Naming depends on the dominance of the three most abundant components quartz, feldspar, or the lithic fragments that originated from other rocks. All other minerals are considered accessories and not used in the naming of the rock, regardless of abundance.
  Quartz sandstones have >90% quartz grains
  Feldspathic sandstones have <90% quartz grains and more feldspar grains than lithic grains
  Lithic sandstones have <90% quartz grains and more lithic grains than feldspar grains
  Abundance of muddy matrix material between sand grains
  When sand-sized particles are deposited, the space between the grains either remains open or is filled with mud (silt and/or clay sized particle).
  "Clean" sandstones with open pore space (that may later be filled with matrix material) are called arenites.
  Muddy sandstones with abundant (>10%) muddy matrix are called wackes.
  Six sandstone names are possible using the descriptors for grain composition (quartz-, feldspathic-, and lithic-) and the amount of matrix (wacke or arenite). For example, a quartz arenite would be composed of mostly (>90%) quartz grains and have little or no clayey matrix between the grains, a lithic wacke would have abundant lithic grains and abundant muddy matrix, etc.
  Although the Dott classification scheme is widely used by sedimentologists, common names like greywacke, arkose, and quartz sandstone are still widely used by non-specialists and in popular literature.
caption: Sedimentary rock with sandstone in Malta
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