Open map List

Contour line

A contour line is a line on a map that connects points of equal elevation above or below a reference point, usually sea level. Contour lines are used in topographic maps to represent the shape, height, and slope of the terrain, helping users visualize landforms in a two-dimensional format.

Basic

Introduction

Key Characteristics of Contour Lines:

  1. Equal Elevation – Every point along a contour line has the same height above sea level.
  2. Contour Interval – The vertical distance between two adjacent contour lines, which remains constant on a given map (e.g., 10 meters or 50 feet).
  3. Close vs. Wide Spacing:
    • Closely spaced lines indicate steep slopes.
    • Widely spaced lines indicate gentle slopes or flat terrain.
  4. Never Cross Each Other – Since one point cannot have two different elevations, contour lines never overlap or intersect (except at vertical cliffs).
  5. Form Closed Loops – Even if they extend off the map, contour lines always form a continuous loop.
  6. V-Shape in Valleys & Streams – Contour lines form a "V" shape pointing upstream when crossing rivers or valleys.

Explanation

Types of Contour Lines:

🔹 Index Contours – Thicker lines with labeled elevations, appearing at regular intervals.
🔹 Intermediate Contours – Thinner lines between index contours, providing finer detail.
🔹 Supplementary Contours – Dashed or dotted lines used for minor elevation changes in flat areas.
🔹 Depression Contours – Indicated with hachure marks, showing sinkholes or craters.

📍 Example: A topographic map of the Grand Canyon uses contour lines to illustrate the steep cliffs and deep valleys.

Outgoing relations