Maps and Compass

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Maps and Compass
2012-11-04 15:15:43
FF1 academy

Maps and Compass
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  1. 3 classifications of maps
    • planimetric-road maps, specific area maps, schematic maps
    • topographic- contour maps, shaded relief maps
    • orthophoto- satellite or aerial pictured maps
  2. US national accuracy standards
    1947- required accuracy within a few cm.
  3. representative fraction
    • 1:24,000 most common for topographic maps
    • proportion of map distance to actual ground distance in like units
  4. graphic scale
    • comparison of map distance to actual ground distance in different units
    • determined by: ground distance/measured distance between two points on map
  5. cardinal directions, top of map
    N is the top of the map. E S W
  6. declination
    • difference between true north and magnetic north in relation to your location
    • only necessary when navigating with a map
  7. Colors on topo map
    • Black- cultural/ man made features and boundaries
    • Blue- water features, ice
    • Green- vegetation
    • Brown- contour lines, relief features
    • Red- main roads, boundaries, special features
  8. ICS display symbols
    Black, Red, Blue, Orange, Green, Brown, Purple, Grey
    • Black: control line, branches, divisions, segments, dozer line( black with X's)
    • Red: fire origin, hazards, spot fire, active fire edge
    • Blue: water sources, ICP, base, staging, repeater site
    • Orange: projected fire expansion
    • Green: vegetation
    • Brown: contours, cuts and fills, relief features
    • Purple: revised info
    • Grey: developed areas
  9. Contour lines 
    connect points of equal elevation
  10. contour interval
    ground distance between contour lines. usually 40 ft.
  11. contour index
    every fifth line is bold
  12. V contour
    streams point up stream
  13. U contour
    ridges- u points down ridge
  14. M or W contour
    stream confluences
  15. contour line are always           to streams
  16. contour lines do not....
    cross, fork, or touch, except overhanging cliffs
  17. closely,widely, and equally spaced contour lines
    • -steep terrain
    • -gradual/gentle terrain
    • - uniform terrain
  18. slope is expressed in...
  19. slope- one percent slope
    100% slope
    how to calculate slope
    • one percent slope= 1' of rise every 100' horizontal distance 
    • 100%= 45 degree 100' of rise over 100' horizontal

    % slope= VDx100/HD
  20. aspect
    direction a slope is facing
  21. how many chains in a mile
  22. acres in a sq. mile
  23. hectare
    2.4 acres
  24. acre in chains
    10 sq chains
  25. estimating acreage
    • area in ft/ 43560
    • area in chains/ 10
  26. tools used to estimate acreage
    • dot grid
    • planimeter
    • GPS
  27. latitude lines
    • run E-W parallel to equator
    • equator is 0 degrees, poles are 90 degrees
    • one degree= 60 mins= 69 miles
  28. longitude lines
    • lines run N-S, converge at poles
    • prime meridian is Greenwich, England
    • one degree approximately 67 miles...varies
  29. public land survey system
    • uniform method to describe and convey land titles( legal location)
    • replaced meets and bounds system
    • Mt. Diablo, Mt. Pierce, San Bernadino are base points for CA
    • 31 initial points in lower 48 states each with base point and principal meridians
  30. township
    • 6 miles apart, lines run E-W
    • 4 townships between standard parallel
    • Township north, Township south to describe
    • 36 sections in each township
  31. Range
    • 6 miles apart, lines run N-S
    • 4 ranges between guide meridian
    • described Range West, Range East
  32. azimuth
    always read at index pointer