PRACTICE READING Topographic Maps

sea level

0 feet/meters in elevation

Contour Line

A line on a topographic map connecting points with the same elevation.

topographic map

A map that shows elevation surface Also shows features (topography) of the earth. Natural features like rivers, lakes, mountains. Man made features like cities, roads, bridges.

Depression Contours

Contour lines with a short, straight lines drawn along the inside of the loop pointing towards its center that indicates a depression.

Relief

Difference in elevation between the highest and lowest points of an area.

Index Contours

Every fifth contour line on a topographic map that is printed bolder for reference. Index Contours are usually labeled.

Depression Contours

Represented on a topographic map by a series of concentric closed contours with the inner contours having lower elevation than their outer surrounding. There are small tick marks or hachures on these contour lines pointing towards lower elevation. Such contours are called hachured contour lines or depression contour lines.

Contour Interval

The difference in elevation between one contour line and the next. SOMETIMES THE CONTOUR INTERVAL IS LABELED ON YOUR MAP - LOOK FOR IT, AS THIS WILL SAVE YOU A LOT OF WORK! However, if it is not, you can easily calculate it. To calculate the contour interval, count how many contour lines are between labeled index contours, and divide equally between the difference between these labeled index contours. Example: if one labeled index contour is 300m and the next labeled index contour is 400m, and there are five contour lines between them, calculate 400-300=100; then divide 100 into 5 equal parts, which is 20. The contour interval is 20m

The scale used on your map

When hiking, it is important to note this piece of information, when planning your hike.

steep slope

When the contour lines on a topographical map are close together

Cross-section view (profile) of land surface

a "side view" of the landscape along a specific line on the map. Because maps are two-dimensional but represent three dimensions, a cross section view helps you visualize what the land surface looks like from the side

elevation

height above sea level

gentle slope

shown by widely spaced contour lines

stream valley

shown when contour lines form a "v" or "u" shape - the "v" points to the area with higher elevation.