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Shale identification and geology

A fine-grained clastic sedimentary rock composed predominantly of clay minerals and silt-sized particles, characterized by fissility—the ability to split into thin, roughly parallel layers along bedding or lamination planes. Shale is the most abundant sedimentary rock type, comprising approximately 50% of all sedimentary rocks. It forms in low-energy environments such as deep marine basins, lakes, lagoons, and floodplains. Field: sedimentology. Example: The Marcellus Shale in the Appalachian Basin is a Middle Devonian organic-rich black shale that has become one of the largest natural gas-producing formations in the world through hydraulic fracturing technology.. Related terms: Mudstone, Fissility, Clay mineral, Lamination.

Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

Editorial owner
GeoMiner
Last updated
2026-03-30T15:19:42.096023+00:00
Review status
Published; not independently peer-reviewed
  • USGS Thesaurus — U.S. Geological Survey. Controlled earth-science terminology used to describe USGS information resources.
  • Glossary of Geologic Terms — U.S. National Park Service. Geologic definitions prepared by the NPS Geologic Resources Inventory.

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Common questions

What does Shale mean in geology?
A fine-grained clastic sedimentary rock composed predominantly of clay minerals and silt-sized particles, characterized by fissility—the ability to split into thin, roughly parallel layers along bedding or lamination planes. Shale is the most abundant sedimentary rock type, comprising approximately 50% of all sedimentary rocks. It forms in low-energy environments such as deep marine basins, lakes, lagoons, and floodplains.
What is an example of Shale?
The Marcellus Shale in the Appalachian Basin is a Middle Devonian organic-rich black shale that has become one of the largest natural gas-producing formations in the world through hydraulic fracturing technology.
Which earth-science field uses the term Shale?
Shale is used in sedimentology.
Which terms are related to Shale?
Related terms in this reference are Mudstone, Fissility, Clay mineral, Lamination.

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