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 XXXXX 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 NEXT remember to check.
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.XXX NEXT XXX XXX
• It is important to remember that the closer together the contour lines the steeper the slope.XXXX Steep slopesXXXX Area that is flatter with only a gentle slopeXXXX•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 Now let’s plot those points XXXX Now if we plotted those points on paper. 300m 250m 200m 150m 100mSea level See how these lines are closer together on the steeper slope NEXT
Think where is the steepest slope on this island? Click here to see if you’re rightxxx 200 150 100 50 XXXX XXXX
Steepest slope – contour lines are closest togetherxxx Sparrow point 227 200 . 76 150 100 50 Sometimes spot heights can be shown as a dot with a note of XXXX the height of that particular place. 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 theshape and pattern of the contours NEXT
A valley may look like this… 150 12090Often with a river running down through the valley NEXT
However a spur can look very similar ! 90 120150 But here the heights are increasing in the opposite direction – always double check which way the NEXT contours are increasing or decreasing.