contour interval
C2 / Very low-frequencyHighly technical (specialised)
Definition
Meaning
The constant vertical distance (difference in elevation) between adjacent contour lines on a topographic map.
In a broader sense, the specific, recurring difference between successive values in a sequence of measurements or data points, providing a quantifiable increment of change.
Linguistics
Semantic Notes
This is a compound noun where 'contour' refers to a line on a map and 'interval' refers to the space or difference between two things. The meaning is fixed within cartography and geology. It is often preceded by a determiner (e.g., 'a contour interval of 10 feet').
Dialectal Variation
British vs American Usage
Differences
No significant difference in meaning. British usage may more commonly cite vertical distance in metres, while US usage may cite feet. The spelling of 'contour' and 'interval' is identical.
Connotations
No difference in connotation. It is a purely technical term.
Frequency
Extremely rare in general discourse in both variants, used exclusively within cartography, geology, surveying, and related technical fields. Frequency is identical.
Vocabulary
Collocations
Grammar
Valency Patterns
The contour interval is [number + unit] (e.g., is 5 metres).A map has a contour interval of [number + unit].Use a [descriptor] contour interval (e.g., a standard contour interval).Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “None. It is a technical term and does not feature in idiomatic expressions.”
Usage
Context Usage
Business
Not used.
Academic
Used in geography, geology, civil engineering, and environmental science papers and textbooks when describing topographic maps.
Everyday
Virtually never used. An everyday speaker would describe a map as 'steep' or 'hilly' rather than reference the contour interval.
Technical
Core term in cartography, surveying, hiking map guides, geological surveys, and military planning.
Examples
By Part of Speech
verb
British English
- Not applicable. 'Contour interval' is exclusively a noun phrase. One can 'contour' land, but 'contour interval' is not verbalised.
American English
- Not applicable. 'Contour interval' is exclusively a noun phrase. One can 'contour' land, but 'contour interval' is not verbalised.
adverb
British English
- Not applicable.
American English
- Not applicable.
adjective
British English
- Not applicable as an adjective. It can be used attributively in a noun phrase: 'contour-interval selection'.
American English
- Not applicable as an adjective. It can be used attributively in a noun phrase: 'contour-interval specification'.
Examples
By CEFR Level
- (Not applicable for this C2-level term. A simpler alternative would be used.) On a map, lines show hills. The space between them shows how steep it is.
- (Rare at this level. Simplified explanation.) The map's key said the contour interval was 10 metres, meaning each line was 10 metres higher than the last.
- For easier reading of the gentle slopes, the cartographers used a contour interval of just 5 feet.
- The geological survey map, with a contour interval of 20 metres, clearly revealed the fault line's dramatic escarpment. A smaller interval would have added unnecessary detail for this regional study.
Learning
Memory Aids
Mnemonic
Imagine a CONTOUR line tracing the shape of a hill. The INTERVAL is the regular VERTICAL step between these lines, like the equal spacing between rungs on a ladder going up the hill.
Conceptual Metaphor
THE LANDSCAPE IS A TOPOGRAPHICAL MAP: The abstract representation (map lines with a fixed interval) conceptually structures our understanding of the physical landscape's elevation changes.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid direct calque from Russian 'контурный интервал' as it is not a standard term. The correct equivalent is 'высота сечения' or 'сечение рельефа'.
- Do not confuse with 'интервал' meaning a time period; here it is exclusively a spatial/vertical difference.
Common Mistakes
- Using 'contour interval' to refer to the horizontal distance between lines (that is the 'contour spacing', which varies with slope).
- Pronouncing 'contour' as /kənˈtaʊə(r)/ (like the beauty term) instead of /ˈkɒn.tɔː(r)/ or /ˈkɑːn.tʊr/.
- Treating it as a general term for any gap or space.
Practice
Quiz
What does 'contour interval' specifically refer to on a topographic map?
FAQ
Frequently Asked Questions
Not exactly. It is specifically the vertical (elevation) difference. The horizontal space on the map between lines varies depending on how steep the actual terrain is.
Typically, a single, standard contour interval is used for consistency across a map sheet. However, supplementary contour lines (like intermediate or index lines) may use a multiple or fraction of the main interval for added detail in specific areas.
There is no single 'typical' value. It depends on the map's scale and purpose. A large-scale hiking map might use a 10-metre interval, while a small-scale atlas map of a continent might use a 500-metre interval. Common intervals are 1, 2, 5, 10, 20, 50, 100 (in metres or feet).
It allows you to quantify the steepness of slopes (gradient) and calculate elevation gains/losses precisely. Without knowing the interval, contour lines only show shape, not magnitude of elevation change.