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Topo Maps PowerPoint Presentation

Topo Maps

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Topo Maps

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Presentation Transcript

  1. Topo Maps

  2. Map Projections • All projections contain distortion except along the intersection of the map projection plane with the Earth’s surface • Map projections are developed to preserve one of four characteristics • Scale (distance measurements) • Shape (geographical representations) • Direction (navigation) • Area (Agricultural estimates) • Important to use the map projection that best suits your needs • Mercator, Universal Transverse Mercator (UTM), Polar Stereographic

  3. Map Scales • Ratio of distance on map to distance on Earths surface • 1:24,000 scale (1” on map = 24,000” on ground) • The larger the number the smaller the scale • 1:24,000 • 7.5 min map • Covers 7.5 min of lat/lon • Most used type of topo map

  4. Scale Comparison1:24,000 1:100,000 1:250,000

  5. Topo Maps • Flat representation of the Earth’s 3-dimensional surface • Use symbols to define locations and types of features • Mark grids of several different coordinate systems

  6. Map Parameters • Quad name and location • Upper and lower right corners • Location relative to state outline • Names of adjacent quads • Scale and contour interval • Bottom center • Scale bars in km and mi • Note subdivisions for refining distance estimates • Projection and datum • Lower left corner or center

  7. Coordinate Systems • Latitude/Longitude • Degrees/minutes/seconds • 360/60/60 • 7.5 mins square • Tic marks every 2.5mins • Universal Transverse Mercator (UTM) • Measured in meters from equator and prime meridian • Northing and easting • Tic marks every 1000 meters • Township and Range (36mi2) • In red on border • T20S = township 20 south • R15E = range 15 east • 6x6 square miles numbered sections (1-36) • Subdivide by quarters reading backwards

  8. Contour Lines • A succession of points defining a line of equal elevation above a datum (usually Mean Sea Level-MSL) • Must eventually close • Never cross • Contour interval • Elevation change between two adjacent lines • Heavier lines at 100 divisions • Interpretations • Rise over run • Steeper = closer together • Flatter = farther apart • Law of the V’s • Contour lines V upstream or upslope • Depressions are hatched • Feet vs meters

  9. Topo Map Symbols