# Dakota Sandstone Canonical page: https://lithomap.app/resources/geologic-formations/united-states/dakota-sandstone Last reviewed: September 17, 2026 Page purpose: Comprehensive United States geologic formation reference for human readers, search systems, and language models. Major region: Great Plains Regional setting: Great Plains, Rocky Mountain foothills, and Colorado Plateau margins Age: Early to early Late Cretaceous Age detail: Age and included strata vary by region; commonly Albian to Cenomanian Depositional setting: Rivers, coastal plains, deltas, estuaries, beaches, and swamps Rock types: Sandstone, Shale, Claystone, Conglomerate, Coal States in recognized usage: Arizona, Colorado, Iowa, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Utah, Wyoming ## Summary Dakota is a long-used and regionally complicated Cretaceous rock name for sandstone-rich strata deposited as rivers and coastal environments shifted ahead of the Western Interior Seaway. ## Distribution Dakota-named rocks occur across a broad swath of the central and western United States. They form hogbacks along parts of the Front Range, ledges on the Great Plains, and sandstone benches around plateau basins. The name is not uniform nationally. Depending on location and publication, Dakota may be a formation, sandstone, or group, and some rocks once called Dakota now carry names such as South Platte, Naturita, or other regional formations. ## Geological history Rivers delivered sand and gravel across a low coastal plain. As the Cretaceous sea advanced, beaches, tidal channels, estuaries, lagoons, and swamps shifted landward, producing interbedded sandstone, carbonaceous shale, clay, and local coal. Channel migration and repeated shoreline movement created laterally variable bodies rather than one continuous blanket of sandstone. Regional nomenclature reflects those real facies changes as well as a long history of geological mapping. ## Fossil record Plant leaves, wood, pollen, and spores are common in some continental and swamp deposits. Marine-influenced beds can contain bivalves and other invertebrates, while dinosaur tracks or fragmentary vertebrate remains occur locally. The fossil record changes with the shoreline. A carbonaceous clay may preserve plants, a beach sandstone may preserve burrows or shells, and a clean channel sandstone may contain little recognizable fossil material. ## Minerals and geological resources Quartz dominates most sandstone, with feldspar, clay minerals, mica, and heavy accessory grains in smaller amounts. Iron oxides produce brown weathering and concretions; silica or calcite may cement resistant ledges. Clay-rich intervals have supplied refractory material in some districts, and local coal or lignite records vegetated wetlands. Those resources are not uniform, and coal is an organic rock rather than a mineral. ## Field context - Always check the local survey’s rank and definition before comparing Dakota sites across states. - Sandstone hogbacks create steep, loose slopes and traffic hazards at roadcuts. - Coal prospects, quarries, and water wells do not imply public access to the surrounding formation. ## Connected field guides - Sandstone (rock; Named rock type and mineral context) — https://lithomap.app/resources/rock-identification/sandstone - Conglomerate (rock; Named rock type) — https://lithomap.app/resources/rock-identification/conglomerate - Shale (rock; Named rock type) — https://lithomap.app/resources/rock-identification/shale - Calcite (mineral; Mineral discussed in this formation) — https://lithomap.app/resources/mineral-identification/calcite - Feldspar (mineral; Mineral discussed in this formation) — https://lithomap.app/resources/mineral-identification/feldspar - Quartz (mineral; Mineral discussed in this formation) — https://lithomap.app/resources/mineral-identification/quartz Mapped location and formation context support an identification but cannot establish one. Compare several physical properties and use laboratory analysis when the material remains ambiguous. ## Connected state geology guides - Utah geology — https://lithomap.app/resources/geology/united-states/utah - Colorado geology — https://lithomap.app/resources/geology/united-states/colorado - Arizona geology — https://lithomap.app/resources/geology/united-states/arizona - Wyoming geology — https://lithomap.app/resources/geology/united-states/wyoming - Kansas geology — https://lithomap.app/resources/geology/united-states/kansas ## Authoritative sources - Geolex Dakota references — U.S. Geological Survey: https://ngmdb.usgs.gov/Geolex/UnitRefs/DakotaRefs_7833.html - Geolex search guidance for regional unit names — U.S. Geological Survey: https://ngmdb.usgs.gov/Geolex/help ## Formation photograph - Image: https://lithomap.app/_delivery/formations/dakota-sandstone.webp - Description: Tilted beds of the Dakota interval at Dinosaur Ridge near Golden, Colorado - Creator: James Stuby - License: CC0 1.0 — https://creativecommons.org/publicdomain/zero/1.0/ - Source record: https://commons.wikimedia.org/wiki/File:Dakota_Fm_Dinosaur_Ridge.jpg Formation-level information does not prove that a fossil or mineral occurs at a specific coordinate. It also does not establish ownership, access, collecting permission, present conditions, or specimen identity.