Map Marginal Information

Map Reading M100 Map Marginal Information (Lesson 1) Marginal Information provides you with information and instructions on the map’s proper use – not all maps are identical! Due to peculiarities relative to specific areas of the earth Marginal Information: Sheet Number – identifies this map sheet from all other map sheets in the same area (lower left hand corner, includes the adjoining map sheet numbers and Grid zone designators) Scale of the Map – includes a scale in meters, miles and yards Legend Information: includes symbols that represent buildings, roads, industrial installations, boundaries and control points, relief and terrain, vegetation, hydrography and miscellaneous cultural features Magnetic Information: Grid vs Magnetic North M100 Map Marginal Information (Lesson 1) Standard Map Colors Blue = Drainage (streams, rivers, lakes, swamps) Green = Vegetation (orchards, grasslands, woods) Brown = Elevation & Relief (contour lines) Black = Man-Made Features (roads, mines, quarries, buildings) Red = (Main roads, build-up areas, and special features) Reddish-Brown = (Cultural features and relief features on read-light readable maps) M100 Map Marginal Information (Lesson 1) GRID REFERENCE BOX: the grid reference box appears in the marginal information of each map sheet. It contains step-by-step instructions for using the grid and the US Army military grid reference system. The grid reference box is divided into two parts The left portion identifies the grid zone designation and the 100,000-meter square. If the sheet falls in more than one 100,000-meter square, the grid lines that separate the squares are shown in the diagram and the letters identifying the 100,000-meter squares are given The right portion of the grid reference box explains how to use the grid and is keyed on the sample 1,000-meter square of the left side M100 Identify Terrain Features (Lesson 2) Elevation Contour Lines are used to illustrate terrain features on the map Elevation Contour Interval: vertical distance between contour lines Contour Lines: a line on a map representing the imaginary line on the ground Datum Plane (reference point to make vertical up and down measurements – military maps use sea level halfway between high and low tides M100 Identify Terrain Features (Lesson 2) Contours Lines display terrain and landforms in a vertically measurable form. Three types of contour lines: Index: A thick printed line indexed to show the elevation above and below sea level. Every fifth line will normally be an index contour line Intermediate: A thin solid line connecting points of equal elevation Supplementary: Thin broken line representing half a contour intervals M100 Identify Terrain Features (Lesson 2) Characteristics of Contour Lines Form smooth flowing curves which normally close on themselves either on your map sheet or on an adjacent map sheet Lines close together indicate a steep slope and far apart a gentle slope Uniform slopes, lines will be evenly spaced, irregular slopes, they are unevenly spaced Movement parallel to contour lines is relatively level. Across them or down slope. M100 Identify Terrain Features (Lesson 2) X What is the elevation of the point (X) on the adjacent map? M100 Identify Terrain Features (Lesson 2) 5 Major Terrain Features Hill Saddle Valley Ridge Depression Minor Terrain Features Wadi Dry Lake Draw Spur Cliff Find on your maps the following: Hill, Depression, Ridge, Wadi, Dry Lake M100 Identify Terrain Features (Lesson 2) Determine the Elevation of the Umm ar Ruwaysat Guard Post What type of Contour line? What type of Contour line? Index, Intermediate, or Supplementary M100 Plot Grid Coordinates (Lesson 3) The protractor represents the azimuth circle Outer scale in mils and inner scale in degrees Each small tick mark equals either 1 degree or 20 mils When measuring azimuths be sure to align the protractor on the map – Base line aligned along the North/South Grid line Zero or 360 degree must be pointed north M100 Plot Grid Coordinates (Lesson 3) The military Grid System uses 100,000 meter squares superimposed on each grid zone segment. Each 100,000 meter square has two identification letters from the alphabet What is the Grid Zone designator for the Military Maps in front of you? M100 Plot Grid Coordinates (Lesson 3) M100 Plot Grid Coordinates (Lesson 3) M100 Plot Grid Coordinates (Lesson 3) M100 Plot Grid Coordinates (Lesson 3) What is the six digit grid coordinates to the point (X) on the adjacent map? 1000 9 8 7 6 5 4 3 2 1 0 1000 9 8 7 6 5 4 3 2 1 0 X M100 Determine the Distance between Points (Lesson 4) BAR SCALES M100 Determine the Distance between Points (Lesson 4) MEASURING STRAIGHT DISTANCE M100 Determine the Distance between Points (Lesson 4) MEASURING ROAD or CURVE DISTANCE Tick mark system Use a narrow strip of paper and rotate along the curve road Hold paper tight, only rotate up or down slightly along the curve Mark start and stop points, then align against the bar scale M100 Determine an Azimuth (Lesson 5) M100 Determine an Azimuth (Lesson 5) 1000 9 8 7 6 5 4 3 2 1 0 1000 9 8 7 6 5 4 3 2 1 0 X 170 3000 X 3200 Friendly Position Enemy Position What is the azimuth to the enemy location on the adjacent map? M100 Determine Polar Coordinates (Lesson 6) You determine polar coordinates by plotting an azimuth and distance from a known point. We will now work several problems on your maps. M100 Convert Magnetic Azimuths to Grid (Lesson 7) True North is a line from any position on the earth’s surface to the north pole Magnetic North is the direction to the North magnetic pole (compass needle points to this direction) Grid North is established using the vertical grid lines on a map Because the G-M angle on your map is nearly negligible, converting the magnetic to grid and vice versa is optional GN G-M angle 24 mils or 1 degree and 24’ To convert a magnetic azimuth to grid azimuth add G-M angle Grid convergence 23 mils or Or 1 degree and 17’ To convert a grid azimuth to a magnetic azimuth subtract G-M angle MN TN M100 Convert Magnetic Azimuths to Grid (Lesson 7) Requirement: Convert these Grid Azimuths to Magnetic Azimuths and Magnetic Azimuths to Grid Azimuths: Mag AZ 54 ̊ Grid Az 183 ̊ Mag Az 216 ̊ G M Any Azimuth Line 10 ̊ Solution: Grid AZ 44 ̊ Mag Az 193 ̊ Grid Az 206 ̊ M100 Locate an Unknown Point on the Ground (Lesson 8) Intersection: Used to determine the location of an unknown point or object by occupying at least two, preferably three, positions and determining the Azimuth to the unknown point 1.) Sight the enemy on the ground 2.) Locate your position on the ground 3.) Determine the magnetic azimuth from your location to unknown point (convert to Grid Az) 4.) Draw a straight line along that Grid Azimuth 5.) Move to or call a second known position that can see the unknown position and mark that point on the map 6.) Repeat steps 3 and 4 7.) Where the lines cross is the location of the unknown point 8.) Ideal to use a third point – you form a triangle where all three lines intersect M100 Locate an Unknown Point on the Ground (Lesson 8) We will now execute intersection problems: 1.) You are located at OP 4 at Grid QT 21997510. You see enemy forces along magnetic grid azimuth of . You move to OP 6 at Grid QT 20457381 and can sight in the enemy forces along a magnetic azimuth of . What is the 8-digit Grid Coordinates to the enemy positions? 2.) You are located at the main observation tower at Grid QT 28807880. You see enemy forces along magnetic grid azimuth of . You move to hill top NGN-27 at Grid QT 26497735 and can sight in the enemy forces along a magnetic azimuth of . What is the 8-digit Grid Coordinates to the enemy positions? M100 Determine Your Position (Lesson 9) Back Azimuths Rule 1. If the azimuth is more than 180 degrees or 3200 mils, then subtract either 180 degrees if working with degrees, or 3200 mils if using mils Rule 2. If the azimuth is 180 degrees or 3200 mils or less, then add 180 degree if working with degrees or add 3200 mils if using mils What are the back azimuths for 45, 340 and 210 degrees? What are the back azimuths for 3360, 80 and 5660 mils? M100 Determine Your Position (Lesson 9) Resection: Used to determine the location of an unknown point by sighting on at least two known points and determining azimuths to the unknown point from these positions (when possible use positions that give large angles) 1.) Locate a feature or object identifiable on both the ground and map 2.) Measure the magnetic azimuth to the known position and convert the magnetic azimuth to grid azimuth 3.) Change the grid azimuth to a back and draw a line from the known position backwards towards the unknown position 4.) Locate a second feature or object on both the map and ground 5.) Repeat steps 2 and 3 6.) The point where the two points intersect is your position 7.) Use a third point for accuracy M100 Determine Your Position (Lesson 9) We will now execute resection problems: 1.) From your position you can see OP 4 at Grid QT 21997510 along a magnetic grid azimuth of . You also can see OP 6 at Grid QT 20457381 along a magnetic azimuth of . What is the 8-digit Grid Coordinates to your position? 2.) From your new position, you can see the main observation tower at Grid QT 28807880 along a magnetic grid azimuth of . You also can see hill top NGN-27 at Grid QT 26497735 along a magnetic azimuth of . What is the 8-digit Grid Coordinates to your position? M100