Mapping

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Streams are shown as a blue line on maps.

When contour lines cross a stream it looks like an upside down V.

The point in the V points

upstream. It opens in the direction the water is flowing.

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Reading a topographic map- Depression Contours

Depression contours show areas of lower elevation.

Drawn like contour lines with marks on the inside.

Hachure marks- tick marks on inside of closed circle.

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Reading a topographic map- Hills

Hills are represented on a topographic map by a series of concentric contour lines in a rough circle

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Reading a topographic map- Slope

Closely spaced contour lines represent steep slopes.

Widely spaced contour lines represent gentle slopes.

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Reading a topographic map- Benchmarks

A benchmark is a place where exact elevation is known.

Shown by a B.M. on map

Ex: BM 60

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Reading a topographic map- Colors

The colors on a topographic map are symbolic of different map features.

Blue = water

Green = forest

Brown = contour lines

Black = cultural features (buildings, place names, boundary lines, roads, etc.)

Red = principal roads

Pink = urban areas

Purple = revisions to an older map, compiled from aerial photos. If an area has become urbanized, this may be shown as purple shading on the new, revised map.

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Reading a topographic map- Map Scale

Map scale indicates your distance along the ground, or the amount of ground covered by the map.

USGS- United States Geologic Survey

Ratio- 1:24000

one unit on the map is equal to 24,000 units of the same size on the ground.

Ex:1 inch on the map = 24000 inches on Earth.

Or after converting 1 inch = 2000ft.

Bar scale-indicated by a line or bar with distances marked in miles, feet, or kilometers.

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Reading a topographic map- Map Scale

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Reading a topographic map- Profiles

A topographic profile is a cross-sectional view along a line drawn through a portion of a topographic map.

It is like taking a slice out of a portion of the Earth and looking at it from the side.

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