Contours, relief and cross-sections revision notes

Edexcel International GCSE Geography (4GE1), chapter 11: Geographical skills, specification point G5. Free lesson.

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Contours show the height and shape of the land, while a cross-section shows the land from the side along a line on a map. Reading these features helps you describe slopes and landforms, calculate gradient and interpret relief.

How contours show height and slope

A contour line joins places at the same height above sea level. The height difference between neighbouring contour lines is the contour interval. A spot height gives the exact height at one point. The spacing of the lines shows how quickly the land rises or falls. Close contour lines mean the height changes over a short distance, so the slope is steep. Contours far apart mean the slope is gentle. Almost no contours show land that is flat.

How to identify landforms from contour patterns

The shapes made by contours help you recognise landforms. For a valley or spur, use the direction of the V and compare it with the height numbers. Valley: V shapes point uphill, towards higher numbers. There is often a river at the bottom. Spur: a finger of high ground sticking out from a hillside. Its V shapes point downhill, towards lower numbers. Ridge: long, narrow high ground, shown by long, narrow contour loops. The land falls away on both sides. Plateau: high ground with a flat top and steep edges. Contours are close together at the edges and scarce on top. **Flood…

How to describe a slope using map evidence

A strong answer says both what you can see and what it means. This earns one mark for the map evidence and one for the interpretation. For example: “The contours here are packed tightly, so the slope is steep.” Describe features shown on the map. Do not base your answer on features that are missing.

How to calculate gradient

Gradient describes how steep a slope is. Divide the change in height by the distance, using the same unit for both. Give the result as a ratio.

How to read and draw a cross-section

A cross-section is a side view of the land along a line on the map. Distance along the line goes on the bottom axis and height goes up the side. A transect is the line itself. You can record features found along it, such as land use, underneath the section. A river at the lowest point of a section marks the valley bottom. Close contours on one side of a valley mean that side appears steeper in the cross-section.

How to read other isolines

An isoline joins places with the same value. Contours are isolines for height. The same idea applies to other map lines. Isobars join places with equal air pressure, measured in millibars (mb). Isotherms join places with equal temperature. Lines on sea charts join places with equal depth. A place between two lines has a value between them. Close lines mean the value changes quickly.