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Laccolith identification and geology

A concordant intrusive igneous body that has domed up the overlying strata, creating a mushroom-shaped or lens-shaped mass with a flat floor and an arched roof. Laccoliths form when viscous magma typically felsic to intermediate is injected along a bedding plane and inflates, pushing the overlying rock upward. They are typically 1–10 km in diameter and less than 1 km thick. Field: petrology. Example: The Henry Mountains in Utah are the type locality for laccoliths, first described by G.K. Gilbert in 1877. The intrusions have domed the overlying sedimentary rocks into visible structural domes.. Related terms: Sill, Concordant, Intrusion, Lopolith.

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
2026-03-30T15:19:42.027557+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 Laccolith mean in geology?
A concordant intrusive igneous body that has domed up the overlying strata, creating a mushroom-shaped or lens-shaped mass with a flat floor and an arched roof. Laccoliths form when viscous magma typically felsic to intermediate is injected along a bedding plane and inflates, pushing the overlying rock upward. They are typically 1–10 km in diameter and less than 1 km thick.
What is an example of Laccolith?
The Henry Mountains in Utah are the type locality for laccoliths, first described by G.K. Gilbert in 1877. The intrusions have domed the overlying sedimentary rocks into visible structural domes.
Which earth-science field uses the term Laccolith?
Laccolith is used in petrology.
Which terms are related to Laccolith?
Related terms in this reference are Sill, Concordant, Intrusion, Lopolith.

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