agonic line
TechnicalSpecialized
Definition
Meaning
A line on a map connecting points where the magnetic declination is zero.
A cartographic line denoting where true north and magnetic north align, where a magnetic compass will point directly to the geographic North Pole without correction.
Linguistics
Semantic Notes
Purely scientific/geographical term; no figurative or everyday use. Often used alongside 'isogonic line' (a line connecting points of equal magnetic declination).
Dialectal Variation
British vs American Usage
Differences
No significant difference in definition or usage. Both refer to the same cartographic concept.
Connotations
Neutral, technical term in both dialects.
Frequency
Extremely low frequency in general discourse. Used exclusively in geology, cartography, navigation, and geophysics.
Vocabulary
Collocations
Grammar
Valency Patterns
[Location] is near/on the agonic line.The agonic line [verb: runs/passes/shifts] through [location].Vocabulary
Synonyms
Neutral
Vocabulary
Antonyms
Usage
Context Usage
Academic
Used in geology and geography textbooks and research papers on geomagnetism.
Everyday
Virtually never used.
Technical
Essential in navigation, surveying, cartography, and geophysics.
Examples
By Part of Speech
adjective
British English
- The agonic line's position is constantly shifting.
American English
- Agonic line data is crucial for aviation charts.
Examples
By CEFR Level
- This map has a special line called the agonic line.
- Pilots must account for magnetic declination unless they are flying directly along the agonic line.
- The gradual westward drift of the agonic line across North America has significant implications for historic cartographic analysis.
Learning
Memory Aids
Mnemonic
Agonic sounds like 'a-gone-ic' — think of the magnetic variation being 'gone' along this line.
Conceptual Metaphor
An invisible seam on the Earth where two norths are stitched together.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'изогона' (isogonic line). The Russian equivalent is 'агопическая линия' or 'линия нулевого склонения'.
Common Mistakes
- Mispronouncing as /əˈɡɒnɪk/ (uh-GON-ik).
- Using it to refer to any line of equal magnetic value.
- Confusing with 'isogonic line'.
Practice
Quiz
What is the primary characteristic of the agonic line?
FAQ
Frequently Asked Questions
No, it shifts slowly over time due to changes in the Earth's magnetic field.
No, it is an irregular, curved line on the Earth's surface.
As of recent decades, it runs roughly from the Great Lakes in North America, down through the Gulf of Mexico, and into South America. Its position is continually monitored and updated on navigational charts.
From Greek 'a-' (without) + 'gonia' (angle), meaning 'without angle,' referring to the lack of angular difference between magnetic and true north.