Earth Science Presentation Topographic Maps Earth Science Presentation

Topography Topography The shape of a surface, including its relief and the relative position of features.

Topography Relief – refers to the difference in the highest and lowest elevations on the map. An area with ‘low’ relief would be relatively flat, An area with ‘high’ relief would be more rugged HIGH RELIEF LOW RELIEF

Topographic Maps Topographic Map – a map that uses contour lines to show the changes of elevation at Earth’s surface; - shows natural features such as lakes and streams - shows cultural features such as cities, schools, dams, etc.

Topographic Maps Contour Lines A line on a map that connects points of equal elevation. Elevation refers to height above or below sea level. Contour line 500 Index contour 400 Contour Interval = 20 feet

Topographic Maps Contour Interval – C.I. The difference in elevation between two side-by-side contour lines. 1250 – 1200 = 50 50 feet every 5 lines 50/5 = 10 feet per line Contour Interval = 10 ft. 1250 1200

Topographic Maps Index Contour Every 5th line is darker than the others. Indicates the elevation. Helps determine the C.I. 1250 1200

Which slope is steepest? Reading Contour Lines 1250 1200 1300 1250 1200 Which slope is steepest?

The closer the contours are to each other, the steeper the terrain. Reading Contour Lines 1250 1300 1250 1200 1200 The closer the contours are to each other, the steeper the terrain.

Rules for Topo maps: 1. Contour lines close around hills and basins or depressions. MAP VIEW CROSS SECTION

Rules for Topo maps: 1. Contour lines close around hills and basins or depressions. Hachures – short lines at right angles to the contour lines that indicate depressions. Elevations of hachured contour lines are equal to the adjacent non-hachured line. Usually indicate sink holes, quarries, or other areas of subsidence. 1220 1230 1230 1220 1210 1200

Rules for Topo Maps: 2. Contour lines never cross. If they did it would mean a spot would have two elevations.

Rules for Topo Maps: 3. Contours form V’s that point upstream when crossing creeks.

Contour lines V upstream and water flows downstream.

Maps Map Legend Explanation of meaning of symbols used on a map.