Contours These slides will slowly tell you about contours wait until you see the NEXT  button to move on. NEXT  Click the NEXT only when you are ready to move onto the next slide

Relief or shape of the land is shown by Contours XXXX xxxxxx Contours are those light brown or orange lines you can see on OS maps. A contour line is an imaginary line that joins points of equal height above sea level. The lines are numbered giving the height above sea level in metres. On an OS 1:50000 map the contours will be drawn for every 10 metre rise. Although on this map they are every 3m so always remember to check. XXXXX NEXT 

What use are contours? They can be used to learn about the shape of the land (the relief). A map with only a few contour lines will be flat (and often low lying) If a map has lots of contours it is a mountainous or hilly area. The actual pattern of the lines will tell you more detail about the area too. NEXT  XXX XXX XXX

Let’s have a look at why that is. It is important to remember that the closer together the contour lines the steeper the slope. XXXX Steep slopes XXXX Area that is flatter with only a gentle slope XXXX Let’s have a look at why that is. NEXT 

This is the side view of a hill. Let’s see where this hill reaches these heights XXXX Now let’s plot those points Now if we plotted those points on paper. 300m 250m 200m 150m 100m Sea level See how these lines are closer together on the steeper slope NEXT 

Let’s look at some other examples NEXT 

Think where is the steepest slope on this island? Click here to see if you’re right xxx 200 150 100 50 XXXX XXXX

. 76 Steepest slope – contour lines are closest together xxx Sparrow point 227 200 . 76 150 100 50 Sometimes spot heights can be shown as a dot with a note of the height of that particular place. XXXX XXXX A trigonometrical point (or trig point) shows the highest point in an area (in meters) and is shown as a blue triangle NEXT 

You can spot other features by the shape and pattern of the contours NEXT 

A valley may look like this… 150 120 90 Often with a river running down through the valley NEXT 

However a spur can look very similar ! 90 120 150 But here the heights are increasing in the opposite direction – always double check which way the contours are increasing or decreasing. NEXT 

Valley Spur 150 90 120 120 90 150 NEXT 

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