Contour — Science definition

A line connecting locations of equal elevation.

Where it is taught

In use

A topographic map uses contour lines to connect points at equal elevation.

Topographic Maps & Gradients

Questions using contour

Problem 1

Two maps have different contour intervals. Can line spacing alone rank their slopes?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

No. Convert each map's elevation change and horizontal scale first; spacing is comparable only with compatible scales.

Problem 2

Closed contours can enclose either a hill or a depressionClosed contours can enclose either a hill or a depressionHillDepression150 m170 m150 m130 mHeights rise inward.Hachures and labels show inward fall.Closed contours alone are insufficient; inspect symbols and elevations.
These paired original maps isolate the difference between hills and depressions at the same 20 m interval. Hachure direction and labeled elevation together support the interpretation. The diagrams omit streams; the valley-V convention is explained in the adjoining prose rather than inferred from these circular contours.
Interpret the supplied visual model. Which central region is lower than its surrounding outer contour, and what two clues support that answer?
Answer and explanation

The right panel: its inner contour is 130 m compared with 150 m outside, and its hachures point inward toward lower ground.

The nested shape is similar in both panels. The tick marks and different height sequence change the interpretation.

The right panel: its inner contour is 130 m compared with 150 m outside, and its hachures point inward toward lower ground.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 3

Contour values are 100, 120, and 140 m. Find the contour interval.
Answer and explanation

20 m

Successive values differ by 20 m.

Problem 4

Contour lines close together indicate
  1. gentle slope
  2. steep slope
  3. flat ground
  4. a depression
Answer and explanation

steep slope

The same height change over a shorter horizontal distance means a steeper gradient.

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