Topographic MAPS

What is a topographic map? A topographic map is a map that shows changes and shape in the elevation of land.

Use contour lines to depict accurate changes in elevation.

Contour lines A line on a map representing a corresponding imaginary line on the ground that has the same elevation along its entire length.

Contour Interval Difference in elevation of succeeding contour lines; determined by relief. Contour interval can be calculated by finding the difference in elevation between 2 contour lines. 500

Contour Interval Difference in elevation of succeeding contour lines, determined by relief—the difference in elevation between any 2 points. The contour interval will be given at the bottom of the map.

Rules for Contour Lines 1. Every point on a contour line has the same elevation.

Rules for Contour Lines 2. Contour lines bend upstream or cross a valley (points in direction opposite to the flow of the stream) are called “V”-Shaped. If the stream flows through the valley the “V” will point upstream, or within the direction opposite to the flow of the stream.

“V” points Contour lines form “V’s” that point upstream whenever they cross streams.

“V” Points When you walk straight across a stream, you walk downhill to the stream, and uphill away from the stream. In order to cross a stream and stay at the same elevation, you would have to walk upstream to cross over.

Rules for Contour Lines 3. A contour line of one elevation never crosses or divides a contour line of another elevation. Each contour line is one elevation!! 20 10

Rules for Contour Lines Contour lines form closed loops around hilltops. Depressions are encircled by contour lines with hachure marks. (short lines within the depression that point toward lower elevations.) 100 400 200 300 200 200 100 Depressions Hilltops

Hill or Depression??? To decide if you are looking at a hill or a depression, a. Read the elevation numbers b. Look for hachures 1. Short lines drawn inside a depression 2. They point toward lower elevations

Rules for Contour Lines 5. Contours are widely spaced on gentle slopes and closely spaced on steep slopes. Lines close together = STEEP SLOPE Lines far apart = GENTLE SLOPE 500 300 400 300 200 200 100 100 Steep Slope Gentle Slope

Slopes of Contour Lines Lines farther apart = GENTLE slope Close lines together = STEEP slope