Land Navigation I Presentation Overview Map Basics Definition

Land Navigation I

Presentation Overview ► ► ► ► ► Map Basics § § Definition Marginal Information Map Colors Grid Lines § § Locating Plotting § § Straight-Line Distance Irregular Distance § § Basics Determining Elevation § § Slope Types Hill, Draw, Ridge, Finger, Saddle, Cliff, Depression, Cuts, Fills § § Lensatic Compass Orienting a Map Determine an Azimuth Follow an Azimuth 8 -Digit Grid Coordinate Determining Distance Contour Lines Relief & Terrain Features GM Angle, Azimuth, and North Quiz Next Time: Land Navigation II Questions? 9/26/2021 3

Presentation Overview ► ► ► ► ► Map Basics § § Definition Marginal Information Map Colors Grid Lines § § Locating Plotting § § Straight-Line Distance Irregular Distance § § Basics Determining Elevation § § Slope Types Hill, Draw, Ridge, Finger, Saddle, Cliff, Depression, Cuts, Fills § § Lensatic Compass Orienting a Map Determine an Azimuth Follow an Azimuth 8 -Digit Grid Coordinate Determining Distance Contour Lines Relief & Terrain Features GM Angle, Azimuth, and North Questions? Quiz Next Time: Land Navigation II 9/26/2021 4

Map Basics ► Definition: A map is a mathematically determined representation of the Earth’s surface systematically plotted to scale upon a plane surface. 9/26/2021 5

Map Basics: Marginal Information ► Information map that helps us read & interpret a § Graphic (bar) scales are rulers used to convert horizontal map distance to ground distance ►Right of 0 is primary scale ►Left of 0 is extension scale 9/26/2021 6

Map Basics: Marginal Information (cont. ) PRIMARY SCALE 1000 500 0 1000 2000 3000 4000 5000 METERS EXTENSION SCALE 9/26/2021 7

Map Basics: Marginal Information (cont. ) ► Declination Diagram § True North § Grid North § Magnetic North 9/26/2021 8

Map Basics: Declination Diagram GRID NORTH Note: See Declination Diagram on Handout Map 9/26/2021 TRUE NORTH MAGNETIC NORTH 9

Map Basics: Marginal Information (cont. ) ► Legend § Illustrates and identifies the topographic symbols used to depict prominent features on the map. Symbols on one map may not mean the same things on another map 9/26/2021 10

Map Basics: Legend Includes all kinds of information, from the size/condition of roads to mines, chapels and other man-made features. Note: See Legend on back of Handout Map 9/26/2021 11

Map Basics: Marginal Information (cont. ) ► Map Scales § Representative Fraction is the scale of the map which expresses the ratio of horizontal distance on the map to the corresponding horizontal distance on the ground: ► 1: 25, 000 SCALE. ► 1: 50, 000 SCALE ► 1: 100, 000 SCALE ► 1: 250, 000 SCALE § The smaller the number on the bottom, the larger the scale of the map 9/26/2021 12

Map Basics: Map Scales (cont. ) ► Small scale maps - Maps that have a scale of 1: 1, 000 and smaller. These maps are used for general planning and for strategically studies at the higher echelons. ► The standard small scale map is 1: 1, 000 9/26/2021 13

Map Basics: Map Scales (cont. ) ► Medium scale maps - Are maps of scales that are larger than 1: 1, 000 but smaller than 1: 75, 000. ► These maps are used for planning operations, including the movement and concentration of marines and supplies. ► The 9/26/2021 standard medium scale map is 1: 250, 000. 14

Map Basics: Map Scales (cont. ) ► Large scale maps - Are maps that are 1: 75, 000 and larger. ► They are used to meet tactical, technical, and administrative needs of the field units. ► The 9/26/2021 standard Large scale map is 1: 50, 000. 15

Map Basics: Colors ► Black: Man-made objects § Buildings, some roads, cultural, etc. ► Red: Main roads § Also some special features ► Blue: Water features § Lakes, rivers, ponds, ocean, etc. ► Green: Vegetation § Forrest, orchard, etc. ► Brown: Relief features § Contour lines. 9/26/2021 16

Map Basics: Grid Lines ►A series of straight lines intersecting at right angles forming squares ► Horizontal grid lines run grid west to grid east ► Vertical grid lines run grid south to grid north ► On most military maps a grid square is 1000 X 1000 meters ► Basic Rule: Read right on the vertical lines, then up on the horizontal grid lines 9/26/2021 17

Map Basics: Grid Lines 23 22 21 20 3818000 m. N 19 546000 m. E 9/26/2021 47 48 49 50 51 52 53 54 18

Presentation Overview ► Map Basics § § ► ► ► ► Definition Marginal Information Map Colors Grid Lines 8 -Digit Grid Coordinate § § Locating Plotting § § Straight-Line Distance Irregular Distance § § Basics Determining Elevation § § Slope Types Hill, Draw, Ridge, Finger, Saddle, Cliff, Depression, Cuts, Fills § § Lensatic Compass Orienting a Map Determine an Azimuth Follow an Azimuth Determining Distance Contour Lines Relief & Terrain Features GM Angle, Azimuth Conversion, and Norths Quiz Next Time: Land Navigation II Questions? 9/26/2021 19

8 -Digit Grid Coordinate ►A grid square’s coordinates are found by combining the values of the vertical and horizontal grid lines that intersect at the lower left hand corner of the grid. § Always, read right, then up § A 4 -digit grid coordinate locates a point to within 1000 square meters. 9/26/2021 20

Finding a 4 -Digit Grid Coordinate 23 GRID REFERENCE: 4820 22 21 20 3818000 m. N 19 546000 m. E 9/26/2021 47 48 49 50 51 52 53 54 21

Coordinate Scale ► Divides the grid square more accurately and consistently that estimation § 1: 25000 coordinate scale divides the 1000 square meter block into ten 100 meter divisions, the ten divisions are further divided into 20 meter blocks 9/26/2021 22

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Finding the Grid Coordinate of a Point ► First determine the grid square the point is in. This gives 4 digits: 12 xx 56 xx. ► Next, using correct scale on protractor, align the bottom right corner of the protractor scale to the bottom right corner of the grid square. § Slide the protractor to the left until the right edge of the scale intersects the point. § Read off the horizontal and vertical position: ► 12345678 9/26/2021 24

23 Grid: 49551885 22 21 Gives second two longitude (horizontal) coordinates: 85 Gives second two latitude (vertical) coordinates: 55 20 18 19 46 9/26/2021 47 48 49 50 51 52 53 54 25

Plotting a Grid Coordinate ► Grid Coordinate 12345678 § Divide into horizontal and vertical measurements: 1234 5678 § Next locate primary coordinates that give grid square: ► 12345678: 12 and 56 are primary coordinates that provide the grid square ►The 34 and 78 and determined by using the tick marks on the protractor 9/26/2021 26

Presentation Overview ► ► ► ► ► Map Basics § § Definition Marginal Information Map Colors Grid Lines § § Locating Plotting 8 -Digit Grid Coordinate Determining Distance § § Straight-Line Distance Irregular Distance § § Basics Determining Elevation § § Slope Types Hill, Draw, Ridge, Finger, Saddle, Cliff, Depression, Cuts, Fills § § Lensatic Compass Orienting a Map Determine an Azimuth Follow an Azimuth Contour Lines Relief & Terrain Features GM Angle, Azimuth Conversion, and Norths Quiz Next Time: Land Navigation II Questions? 9/26/2021 27

Determining Distance: Straight Line § The shortest distance between the two points § Lay a straight piece of paper between two points § Make two tickmarks on the paper corresponding to the centers of the two points § Move the paper down to the graphic scale § Make sure you use meters 9/26/2021 28

Determining Distance: Irregular Line ►Used for winding roads, curved lines § Lay paper down so one edge is on the start point, make a tick mark at the start point and another where the edge of the paper leaves the center of the curve/line § Pivot the paper with the pencil on the second point ► to align the paper with the center of the curve, make another tick mark when the paper leaves the center of the curve § Continue until measurement is completed § Transfer paper to the graphic scale to compute the distance 9/26/2021 29

Presentation Overview ► ► ► ► ► Map Basics § § Definition Marginal Information Map Colors Grid Lines § § Locating Plotting § § Straight-Line Distance Irregular Distance 8 -Digit Grid Coordinate Determining Distance Contour Lines § § Basics Determining Elevation § § Slope Types Hill, Draw, Ridge, Finger, Saddle, Cliff, Depression, Cuts, Fills § § Lensatic Compass Orienting a Map Determine an Azimuth Follow an Azimuth Relief & Terrain Features GM Angle, Azimuth Conversion, and Norths Quiz Next Time: Land Navigation II Questions? 9/26/2021 30

Contour Lines: Basics § A contour line is a line drawn on a map representing an imaginary line on the ground along which all points are the same elevation § Indicates the vertical distance above or below a base plane § The vertical distance between two lines is the contour interval, found in the marginal data § Every fifth line is an index contour, it is shaded thicker and heavier § The lines in between are intermediate contours § Every line counted represents a change in elevation equal to the contour interval 9/26/2021 31

Contour Lines: Basics 10 1 3 5 350 4 2 x 358 350 6 9 300 8 7 Intermediate Contour Line 9/26/2021 Index Contour Line Supplementary Contour Line 32

Contour Lines: Determining Elevation ► If a point is on a line its elevation is that of the contour line ► For the estimation of elevation of a point between contour intervals is equal to 1/2 change in contour interval § A hilltop is 1/2 plus the elevation of the contour line around the hilltop unless otherwise stated § A depression is equal to the contour line around the depression minus 1/2 the contour interval 9/26/2021 33

Contour Lines: Elevation 10 2 x 358 350 1 3 4 5 350 6 9 300 8 7 Elevation of Point: 9/26/2021 7=? 10 = ? 3=? 9=? 1=? 4=? 8=? 34

Presentation Overview ► ► ► ► ► Map Basics § § Definition Marginal Information Map Colors Grid Lines § § Locating Plotting § § Straight-Line Distance Irregular Distance § § Basics Determining Elevation 8 -Digit Grid Coordinate Determining Distance Contour Lines Relief & Terrain Features § § Slope Types Hill, Draw, Ridge, Finger, Saddle, Cliff, Depression, Cuts, Fills § § Lensatic Compass Orienting a Map Determine an Azimuth Follow an Azimuth GM Angle, Azimuth Conversion, and Norths Quiz Next Time: Land Navigation II Questions? 9/26/2021 35

Relief & Terrain Features: Slopes ► Evenly spaced and wide apart contour lines indicate a uniform gentle slope ► Evenly spaced and close together contour lines indicate a uniform steep slope ► Lines closely spaced at the top and widely spaced at the bottom is a concave slope ► Lines widely spaced at the top and closely spaced at the bottom indicates a convex slope 9/26/2021 36

Relief & Terrain Features: Slopes Uniform Gentle Slope Uniform Steep Slope Convex Slope Concave Slope 9/26/2021 37

Relief & Terrain Features: Terrain Features ► Hill: Indicated by closed loop. The ground slopes down in all directions ► Draws: Less developed stream courses § ground slopes upward in three sides and down one side. § V points to higher elevation 9/26/2021 38

Relief & Terrain Features: Terrain Features ► Ridge: A line of high ground with normally minor variations along its crest § Not simply a line of hills § The points of the ridge are higher than the ground around it ► Finger: A continous line of sloping ground usually jutting from the side of a ridge 9/26/2021 39

Relief & Terrain Features: Terrain Features ► Saddle: A dip or low point along the crest of the ridge ► Cliff: A vertical or near vertical slope. So steep it is indicated by tick-marks pointing to lower elevation 9/26/2021 40

Relief & Terrain Features: Terrain Features ► Depression: A low-point or sinkhole surrounded on all sides by higher ground § Tick marks point to lower ground § Each ticked contour circles represents a change in elevation equal to one contour interval ► Valley: A stretched-out groove in the land § Usually formed by streams or rivers 9/26/2021 41

Relief & Terrain Features: Terrain Features ► Cuts: places where high ground leveled off 9/26/2021 ►Fills: areas where low areas are filled in 42

Presentation Overview ► ► ► ► Map Basics § § Definition Marginal Information Map Colors Grid Lines § § Locating Plotting § § Straight-Line Distance Irregular Distance § § Basics Determining Elevation § § Slope Types Hill, Draw, Ridge, Finger, Saddle, Cliff, Depression, Cuts, Fills 8 -Digit Grid Coordinate Determining Distance Contour Lines Relief & Terrain Features GM Angle, Azimuth Conversion, and Norths Quiz Next Time: Land Navigation II § § ► Lensatic Compass Orienting a Map Determine an Azimuth Follow an Azimuth Questions? 9/26/2021 43

GM Angle, Azimuth Conversion, and North ► Three Norths § Grid-The vertical lines on the map § Magnetic-Magnetic North in Hudson Bay § True-North Pole ► Declination Diagram shows the relationships between the three norths ► Magnetic and Grid North are used to determine GM (Grid-Magnetic) Angle 9/26/2021 44

Azimuths ► An azimuth is a direction ► Defined as a horizontal angle measured clockwise from a baseline ► There are two types dealt with § magnetic azimuths measured with true north as its base § grid azimuths measures with grid north as base 9/26/2021 45

Measuring Azimuths ► Plot two coordinates on the map ► connect them with a straight line ► Place the index point pf the protractor on the point the azimuth its to be measured from ► Ensure the protractor grid lines are parallel to N-S gridlines on a map ► Where the line crosses the protactor indicates azimuth 9/26/2021 46

Azimuths (cont. ) 23 GN Grid azimuth = 45 degrees 22 21 20 3818000 m. N 19 546000 m. E 9/26/2021 47 48 49 50 51 52 53 54 47

Converting Azimuths ► Use the GM angle to convert grid to magnetic and magnetic to grid ► When going from Grid to Magnetic § LARS ( Left Add/ Right Subtract) § This will almost always be the case ► Magnetic to Grid § LSRA (Left Subtract/Right Add) 9/26/2021 48

Questions?

Presentation Overview ► ► ► Map Basics § § Definition Marginal Information Map Colors Grid Lines § § Locating Plotting § § Straight-Line Distance Irregular Distance § § Basics Determining Elevation § § Slope Types Hill, Draw, Ridge, Finger, Saddle, Cliff, Depression, Cuts, Fills 8 -Digit Grid Coordinate Determining Distance Contour Lines Relief & Terrain Features ► GM Angle, Azimuth Conversion, and Norths ► Quiz ► Next Time: Land Navigation II § § ► Lensatic Compass Orienting a Map Determine an Azimuth Follow an Azimuth Questions? 9/26/2021 50

Quiz ► What is a map? ► What are three types of North? § Explain what they represent. ► What standard colors are § What do they represent? used on a map? ► Explain the 2 main types of contour lines. ► What is an 8 -digit grid coordinate? § How accurate is it is using a 1: 25000 coordinate scale? ► Describe the four types of slope and what they look like on a topographic map. 9/26/2021 51

Quiz (cont. ) ► What is the following terrain feature: ► Is this the GM angle for San Francisco or New York? Why? § If I am going from Grid to Magnetic on a map with this angle, would I add or subtract this angle? 9/26/2021 52

Next Time: Land Navigation II § Lensatic Compass ►Parts ►Using during day ►Using at night § § 9/26/2021 Orienting a Map Determine an Azimuth Follow an Azimuth Pace Count 53