Slopes are identified using the contour lines on Ordnance Survey maps. Remember that the contour lines are spaced 10 metres apart, so the closer the contour lines are to each other, the steeper the slope. There are four types of slope: even, concave, convex and compound.
Even slope
This slope is even and the contour lines are evenly spaced out.
A Concave slope
This shape of slope is shown using contour lines that are spaced out at the base and getting closer together as they near the peak. The slope is gentle at first and then gets steep.
C
B Convex slope
This shape of slope is shown using contour lines that are closer together at the base and become more spread out as they near the peak. The slope is steep at first and then gets gentle near the top.
Compound slope
The contour lines for this slope are sometimes spaced out and sometimes close together, showing that the slope is steep in places and not steep in other areas. It is also called a stepped slope.
G E F H
D
ACT VITY
Read these descriptions of walking up a hill or mountain, and decide what sort of slope each of them describes. It may help you to make drawings.
(a) It was a tough walk. It was quite steep from the beginning and stayed like that all the way to the top.
(b) It wasn't too hard most of the time, but there were several tough, steep sections where we had to use our hands.
(c) It was easy going at first, but the walking got harder and harder as we got closer to the summit.
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Geographical Skills for Second Years: Ordnance Survey and aerial photograph skills
