The Topographic Map

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•What Does Earth Really Look Like?

• A map is a representation of the features of a physical body such as Earth but is drawn on a flat surface.

• The Greeks thought of Earth as a sphere almost 2,000 years before Columbus sailed in 1492.

• Around 240 BCE, Greek mathematician Eratosthenes calculated the circumference of the Earth. His calculation was wrong by only 6,250 km.

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Features of Topographic Maps

TOPOGRAPHY (the shape of the land):

The topography of the land is determined by how uneven the lands surface (hills, mountains, valleys\ and slight depressions (dips) in the land surface.

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Uses for Topographic Maps

• Topographic maps have many uses in science, engineering, business, government, and everyday life for recreational purposes (hiking, canoe trips etc..

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What do topographic maps show?

• A topographic map is a map that shows surface features, or topography, of the Earth.

•Topographic maps also show •- physical shape of the land•- natural elements: vegetation, water•- human made features- buildings, roads...

• Topographic maps also show elevation (flat areas hills, valleys mountains).

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Reading a Topographic Map

• Topographic maps use symbols to represent parts of the Earth’s surface.• • Colors are also used to represent natural or man made features.

•For example, cities and towns are pink, bodies of water are blue, and wooded areas are green.

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Elements of the Topographic

Map

USGS Topographic Map Symbol Website

<click here>

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Map Symbols

Topographic maps usually have a separate sheet with an explanation of map symbols. There is no room on the map for all the symbols

Sample page from USGS Topo Map Symbol Pamphlet

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Topographic Contour Linesconnects points of equal elevation

Rules:Rules:

• Lines never cross

• They are brown

•Lines “V” upstream

•Lines show changes in elevation

•Each contour interval here is 20 metres

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TOPOGRAPHIC MAPDESCRIPTION

• Five basic colors are used for Topographic Maps.– Brown (Contour Lines: shows elevation)– Black (Man Made Features: Buidlings, Roads, Trails)– Blue (Water Features: lakes, rivers)– Green (Vegetation: forests, other)– Red (Highway and Land Grids)– Three minor colors

• Pink (Built up area, civilization)• Purple (Updated Map Information)• White: no forests, might be farmland, meadows

etc…

PART 1 Basic Land Navigation 15

Map SymbolsSymbols are used to represent the natural and man-made features of the earth.

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It is a map language that is simple to read and understand. BUT you must first know what the map symbols represent, in order to understand, read and speak map language to others.

PART 1 Basic Land Navigation 16

Woods

Scrub

Orchard

Vineyard

Mangrove

VEGETATIONVEGETATION Map SymbolsPART 1 Basic Land Navigation 17

Marsh or swamp

Submerge marsh or swamp

Wood marsh or swamp

Submerge wood marsh or swamp

Rice field

Land subject to inundation

SUBMERGED AREAS SUBMERGED AREAS AND BOGSAND BOGS

PART 1 Basic Land Navigation 18

RIVERS, LAKES, AND CANALSRIVERS, LAKES, AND CANALS

Perennial stream

Perennial river

Small falls; small rapids

Large falls; large rapids

Dry lake

Perennial lake or pond

Intermittent lake or pond

Intermittent stream

Dam

Intermittent river

Well or spring

Canal

Map SymbolsPART 1 Basic Land Navigation 19

MAN-MADE FEATURES and MAN-MADE FEATURES and HIGHWAY & LAND GRIDSHIGHWAY & LAND GRIDS

Highway

Road

Dirt Road

Trail

Power Lines

Buildings

Built-up Areas

Airports

Landing Strip

School

Church

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Mine

Gravel Pit

Bridge

Foot Bridge

Railroad

Land Grids

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Map SymbolsPART 1 Basic Land Navigation 20