Reading a topographic map

Reading a Topographic Map

What are topographic maps used for?

Topographic Maps:

• Show surface features of the Earth such as mountains, valleys, craters, lakes, etc

• Show elevation (height above or below sea level)

A picture of elevation:

Sea Level

How to Read a Topographic Map:

Contour Line:

• Connect points of equal elevation

• Each line represents a change in elevation

Contour Interval:

• The amount of elevation between 2 contour lines.

Example:

If the contour interval on this map is 10 feet, what is the elevation of “A”?

Relief:

The difference between the highest and lowest point on the map.

What is the relief on this map?

(Remember the contour interval is 10 feet)

Index Contour:

Darker, heavier lines – usually about every 5-10 lines. These are often the only lines labeled

Golden Rules of Reading Topographic Maps:

1. Contour lines NEVER cross

2. All points on one contour line represent one elevation

3. Closely spaced contour lines mean steep slope

4. Contour lines that are far apart mean gentle slop or flat land

5. Contour lines that cross a valley or stream are v-shaped

a.The v points to higher elevation

b.The v points upstream

Example:

6. Contour lines form closed circles around hills, mountains, and depressions

7. Depressions are marked with short straight lines inside the circle

Example:

You Try It…

Draw a topographic map for a “pretend landscape” that has a relief of 200 ft, 2 hills, 1 depression, a river, a city, and some wooded areas. Use a contour interval of 20 ft.