Topography

What is topographic map? A map showing the surface features of an area Topography is based on an area’s elevation, relief, and landforms

Example:

How to read a topographic map Contour lines Contour intervals Reliefs

Contour Lines A line that connects points of equal elevation. Image an island. (land surrounded by water on all sides). If you walked along the beach where the water and land meet would you be at the same elevation line? If you traced out your path on a map you would have traced out a contour line. A line that follows equal elevation. It might look like this:

Now image that the water rose 10 meters and you walked along the path where the water and land meet up. What would your path look like then?

What if the water rose another 10 meters What if the water rose another 10 meters? How would the contour lines continue to look?

Stacking Contour Lines Contour lines by themselves do not tell you much about the shape of the land but stacking the contour lines together can.

Estimating Elevation

Contour interval The change in elevation from one contour line to the next The shorter the distance between two contour lines, the steeper the slope

Contour Intervals The change in elevation between contour lines. The contour interval is the same for a given map. The index contours are usually given in round numbers. ( ie. 600 meters or 20 meters) Usually index contours are a bolder looking line. The units of the contour are usually given on the map or located within the legend of the map.

How can you find the contour interval?

Interpreting Topographical Maps Contour lines that are close together would represent what? A steep slope – the lines being close together means the elevation is changing a lot in a small distance. Contour lines that are far apart would represent what? A gentle slope – the lines being far apart would represent that the slope is not changing much over a large area.

Interpreting Topographical Maps If you are walking in a direction where the contour lines are decreasing, are you walking uphill or downhill? Downhill If you are walking in a direction where the contour lines are increasing, are you walking uphill or downhill? Uphill

Uphill or Downhill?

Interpreting Topographical Maps Contour lines in the shape of a V indicate a valley or a ridge line. If the V is pointed downhill, that indicates a ridge line. If the V is pointed uphill, that indicates a valley. ( A possible location of a steam or river)

Ridge or Valley?

Relief The difference between the highest and lowest elevations in an area

Real world applications Many uses in science, business, government, and everyday life GPS (hiking climbing, navigating) Planning trips Planning buildings, parks, schools, churches