laccolith
C2Formal, Scientific, Technical
Definition
Meaning
A dome-shaped, concordant igneous intrusion that forces the overlying rock layers into a dome.
In geology, a mass of intrusive igneous rock with a flat base and a convex upper surface, typically formed from magma that intruded between sedimentary layers. More broadly, the term can be used metaphorically to describe any structure or force that causes a doming or swelling from below.
Linguistics
Semantic Notes
Highly specific geological term. It denotes a specific structure, not just any intrusive rock. It is a hyponym of 'igneous intrusion' or 'pluton'.
Dialectal Variation
British vs American Usage
Differences
No significant differences in meaning or usage; the term is identical in geological contexts in both varieties.
Connotations
Purely technical and descriptive, with no extra connotations.
Frequency
Extremely low frequency in both varieties, limited to specialist geology texts, papers, and courses.
Vocabulary
Collocations
Grammar
Valency Patterns
[The/An/A] laccolith [VERB: formed/is exposed/has intruded]Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “None”
Usage
Context Usage
Business
Never used.
Academic
Exclusively used in geology and earth science publications, lectures, and fieldwork.
Everyday
Virtually never used.
Technical
Precise term for a specific geological structure.
Examples
By Part of Speech
adjective
British English
- The laccolithic structure was clearly visible in the cliff face.
- Laccolithic doming can create significant topography.
American English
- The laccolithic intrusion created a distinct uplift.
- We studied the region's laccolithic features.
Examples
By CEFR Level
- Geologists study rocks. (Note: 'laccolith' is too advanced for A2.)
- A laccolith is a type of rock formation found underground.
- The geologist explained that the hill was formed by a laccolith, an intrusion of magma that pushed up the overlying rock.
- The emplacement of the Pine Valley laccolith significantly deformed the Cretaceous sedimentary strata, creating a classic example of a bysmalith.
Learning
Memory Aids
Mnemonic
Imagine a LACquer-coated COLumn of rock pushing up from beneaTH, creating a smooth, domed LACColith.
Conceptual Metaphor
A BLISTER or SWELLING in the Earth's crust; a geological PILLOW pushing up the bedding.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'лаколит' (pronounced /lakolit/), which is a direct transliteration but refers to a specific, older type of polymer, not a geological formation. The geological term in Russian is 'лакколит' (/lakkolit/). Ensure correct technical context.
Common Mistakes
- Misspelling as 'lacolith' (single 'c').
- Confusing it with a 'lopolith' (which is concave).
- Using it as a general term for any large rock formation.
Practice
Quiz
What is the defining feature of a laccolith?
FAQ
Frequently Asked Questions
No. A laccolith is an intrusive igneous body that does not reach the surface. A volcano is an extrusive feature where magma erupts onto the surface.
Famous examples include the Pine Valley Mountain in Utah, USA, and the laccoliths of the Henry Mountains, also in Utah. They are often exposed by erosion.
The American geologist Grove Karl Gilbert first introduced the term in 1877 based on his studies in the Henry Mountains.
A laccolith is dome-shaped (convex upward), while a lopolith is saucer-shaped or basin-shaped (concave upward).