page_title: Geological formation
hierarchical_section_title: Geological formation
caption_attribution_description: Key 6 - Hermit, Coconino, Toroweap, and Kaibab 6d - en:Kaibab Limestone 6c - en:Toroweap Formation 6b - en:Coconino Sandstone 6a - en:Hermit Shale 5 - en:Supai Group 5d - en:Esplanade Formation 5c - en:Wescogame Formation 5b - en:Manakacha Formation 5a - en:Watahomigi Formation 4 - Temple Butte, Redwall, and Surprise Canyon 4c - en:Surprise Canyon Formation 4b - en:Redwall Limestone 4a - en:Temple Butte Limestone 3 - en:Tonto Group 3c - en:Muav Limestone 3b - en:Bright Angel Shale 3a - en:Tapeats Sandstone 2 - en:Grand Canyon Supergroup 1 - en:Vishnu Group 1b - en:Zoroaster Granite 1a - en:Vishnipou Schist Photo of a display in the Grand Canyon visitor's center. Taken and modified by Daniel Mayer.
context_page_description: A geological formation, or formation, is a body of rock having a consistent set of physical characteristics that distinguish it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region. It is the fundamental unit of lithostratigraphy, the study of strata or rock layers.
  A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology, or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock.
  The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Werner in his theory of the origin of the Earth, which was developed over the period from 1774 to his death in 1817.
context_section_description: A geological formation, or formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguish it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers.
  A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock.
  The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Werner in his theory of the origin of the Earth, which was developed over the period from 1774 to his death in 1817.  The concept became increasingly formalized over time and is now codified in such works as the North American Stratigraphic Code and its counterparts in other regions. 
  Geologic maps showing where various formations are exposed at the surface are fundamental to such fields as structural geology, allowing geologists to infer the tectonic history of a region or predict likely locations for buried mineral resources.
caption: A geologic cross section of the Grand Canyon. Black numbers correspond to groups of formations and white numbers correspond to formations (click on picture for more information)
exif: {}