Contour lines - SS1 Geography Lesson Note

Contour lines are lines on a map that connect points of equal elevation above a reference point, typically sea level. They form a continuous loop, and their shape and spacing convey essential information about the landscape.

 

Interpreting Elevation:

Contour lines help us understand the height or depth of the terrain. Each line represents a specific elevation. When you follow a contour line, it means you are staying at a constant elevation above sea level.

 

Intervals:

Contour lines are drawn at regular intervals, known as contour intervals. The contour interval is the vertical distance between adjacent contour lines. For instance, if the contour interval is 10 meters, each contour line represents a change of 10 meters in elevation.

 

Topography and Contour Lines:

The spacing between contour lines provides crucial information about the steepness of the terrain. Closer lines indicate steeper slopes, while widely spaced lines suggest flatter areas.

 

Understanding Features:

Features like hills, valleys, ridges, and depressions can be identified by the pattern of contour lines. For example, a hill is often represented by concentric circles of contour lines, with the innermost circle at the highest point.

 

Contour Line Patterns:

Apart from single circles for hills, other patterns can indicate cliffs, saddles (low points between hills), and spurs (ridges extending from hills). V-shaped lines often mark stream valleys.

 

Depressions and Contour Lines:

In the case of depressions, like craters or sinkholes, contour lines are drawn with hachures (short lines) inside, symbolizing lower elevation within the depression.

 

Closed Contour Loops:

When contour lines form closed loops, it indicates a plateau or a mountain with a flat summit.

 

Reading Elevation Change:

To calculate the elevation change between two points on a map, count the number of contour lines crossed, and multiply it by the contour interval.

 

Map Scale and Precision:

The interpretation of contour lines depends on the map scale. A larger scale map provides more detailed elevation information than a smaller scale map.