Depression contours
Contour lines with short ticks on one side mark a depression: a closed hollow or basin. The ticks are on the downhill side, pointing into the hollow.
Easily confused with
How to read it
The USGS symbol sheet lists depression contours among its contour symbols, drawn as closed brown loops with short ticks (hachures). Esri’s GIS dictionary defines a hachured contour as concentric contour lines with right-angle ticks marking a closed depression or basin, the ticks on the downslope, inside edge of the line. Maricopa Community Colleges’ geography text says the same: the hachures are on the downhill side. Natural Resources Canada’s legend has index and intermediate depression contours, as for ordinary contours.
Also searched as: closed depression, contour with ticks, depression contour, hachured contour, hachure marks.
These pages describe what each symbol on a map shows. They are not navigation instructions: the map’s own legend says what each of its symbols means, and symbols differ between map series and editions.
Look-alikes
Rings of plain Contour lines without ticks are a hill, Esri’s dictionary notes: the land rises towards the smallest ring. With ticks, it falls. On a weather map, closed rings without ticks are isobars round a pressure centre.
Read next
- Next in Topographic map symbolsBenchmark symbolBM on a topographic map marks a benchmark: a permanent survey mark, often a metal tablet, whose elevation has been measured. The number beside it is that elevation.
- The same shape in African flagsFlag of EthiopiaEthiopia’s flag is green, yellow and red in equal horizontal stripes with a blue disc in the centre holding a yellow star of equal lines with yellow rays. Ethiopia’s Flag Proclamation makes the green labour, fertility and development, the yellow hope, justice and equality, and the red sacrifice and heroism for freedom and equality; the blue disc is peace and the star the unity of Ethiopia’s nations, nationalities and peoples.
More topographic map symbols
The same shape elsewhere
Browse symbols drawn with circles or lines.
Sources
- Topographic Map Symbols, USGS General Information Product (first posted 2005), U.S. Geological Survey, Contours: Topographic
- Toporama Legend, Edition 1.2, 2013 (after the NTS 1:50,000 standards and specifications), Natural Resources Canada, Legend
- Hachured contour, GIS Dictionary, Esri, Definition
- Contour Lines, Physical geography lab text (GLG 102), Maricopa Community Colleges (Open Maricopa), Hills and depressions
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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