Contours

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Contours

  1. 1. Contours NEXT  Click the NEXT  only when you are ready to move onto the next slide These slides will slowly tell you about contours wait until you see the NEXT  button to move on.
  2. 2. Relief or shape of the land is shown by Contours <ul><li>Contours are those light brown or orange lines you can see on OS maps. </li></ul><ul><li>A contour line is an imaginary line that joins points of equal height above sea level. </li></ul><ul><li>The lines are numbered giving the height above sea level in metres. </li></ul><ul><li>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. </li></ul>NEXT  xxxxxx XXXXX XXXX
  3. 3. What use are contours? <ul><li>They can be used to learn about the shape of the land (the relief). </li></ul><ul><li>A map with only a few contour lines will be flat (and often low lying) </li></ul><ul><li>If a map has lots of contours it is a mountainous or hilly area. </li></ul><ul><li>The actual pattern of the lines will tell you more detail about the area too. </li></ul>NEXT  XXX XXX XXX
  4. 4. <ul><li>It is important to remember that the closer together the contour lines the steeper the slope. </li></ul><ul><li>Let’s have a look at why that is. </li></ul>Steep slopes Area that is flatter with only a gentle slope NEXT  XXXX XXXX XXXX
  5. 5. <ul><li>This is the side view of a hill. </li></ul>Sea level 100m 150m 200m 250m Let’s see where this hill reaches these heights 300m Now let’s plot those points See how these lines are closer together on the steeper slope NEXT  Now if we plotted those points on paper. XXXX
  6. 6. Let’s look at some other examples NEXT 
  7. 7. Think where is the steepest slope on this island? Click here to see if you’re right xxx XXXX XXXX 50 100 150 200
  8. 8. Sometimes spot heights can be shown as a dot with a note of the height of that particular place. A trigonometrical point (or trig point) shows the highest point in an area (in meters) and is shown as a blue triangle Steepest slope – contour lines are closest together Sparrow point 227 . 76 xxx XXXX XXXX NEXT  50 100 150 200
  9. 9. You can spot other features by the shape and pattern of the contours NEXT 
  10. 10. A valley may look like this… Often with a river running down through the valley 150 120 90 NEXT 
  11. 11. However a spur can look very similar ! But here the heights are increasing in the opposite direction – always double check which way the contours are increasing or decreasing. 90 120 150 NEXT 
  12. 12. NEXT  Valley Spur 90 120 150 90 120 150
  13. 13. Now Try your hand at a short test or click on the return button to re-run this presentation. RETURN For test click here

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