eries of accurately surveyed points called datums, to ensure that the grids are consistent on all maps. Newer Nova Scotia maps use the NAD83 datum. Using the wrong datum can result in grid references being off by hundreds of meters.
39 DATUMS When entering grid references into a GPS, the user must ensure the datum of the GPS is set to the datum of the map. Map datums are located on the bottom margin of the map. Nova Scotia GSAR teams use the NAD83 datum.
40 MAJOR MAP DIVISIONS Topographic maps have three major divisions: Vegetation Water Relief
41 Relief Vegetation Water Example of Major Map Divisions
42 MAP SYMBOLS Symbols are used on maps to represent features on the ground. The key to these symbols is either on the reverse side of the map or in the margin. All map symbols on Canadian topographic maps conform to the following colour code: Black: human-made features Blue: water Green: forest or vegetation Brown: elevation (contours) White: open areas, field or snowfield Red: highways Orange: secondary or dirt roads Pink: high population density areas Purple: updated data
43 Sample map symbols
44 Sample map symbols
45 Sample map symbols
46 Sample map symbols
47 Sample map symbols
48 Sample map symbols
49 TOPOGRAPHIC CONTOURS On topographic maps elevation is indicated with Contour Lines. A contour line on a map is a line that connects points of equal elevation above sea level. The vertical distance between two contour lines is the Contour Interval (C.I.). The contour interval is located on a map s margin.
50 TOPOGRAPHIC CONTOURS The contour interval for ESGSAR searcher maps is 10 meters. Contour lines are usually drawn with reference to sea level. On most topographic maps, every fifth contour line is printed darker for easy recognition and is locally labelled with its elevation. These are called Index Contours.
51 CONTOUR LINE RULES 1. All points on the same line are at the same elevation. 2. All contour lines close somewhere, although it may be outside the map at hand. 3. Contour lines never cross, except when they are representing an overhanging cliff in which case those beneath the overhang are dotted. On a vertical cliff several contour lines may become superimposed. 4. Contour lines never divide. 5. Contours are far apart on a gentle slope.
52 CONTOUR LINE RULES 6. Contours are close together on a steep slope. 7. Contours bend upstream in valleys and cross streams at right angles. 8. On level ground there are no contours. 9. An isolated closed contour has the same elevation as the next adjacent contour. 10. All points inside a depression contour are lower than the line.
53 CARDINAL DIRECTIONS The four cardinal directions on a map are: North (at top of map) South (at bottom of map) East (at right of map) West (at left of map)
54 THE MAGNETIC COMPASS The magnetic compass is an important aid for: Taking bearings Map orientation Position location Triangulation Route finding, etc.
55 THE MAGNETIC COMPASS The magnetic compass works on the principle that the pivoting magnetized needle, will always point to the magnetic north. There are a variety of compasses available, ranging in price from a few dollars to hundreds of dollars.
56 PARTS OF A COMPASS 1. MAGNETIC NEEDLE: Points consistently towards the north magnetic pole. All measurements with the compass are therefore made relative to the magnetic north direction.
57 PARTS OF A COMPASS 2. COMPASS HOUSING AND GRADUATED DIAL: The compass housing is a sealed capsule which contains the magnetic needle. It is filled with a light oil so the needle comes quickly to rest. The outer ring of the housing is graduated in degrees from 0 to 360 in steps of 2 degrees. The north direction is indicated by the set of parallel (meridian) lines on the transparent base plate. The large black arrow which is also on the base plate can be rotated independently by means of a small screw in the graduated metal dial.
58 PARTS OF A COMPASS 3. BASE PLATE AND DIRECTION ARROW: Used in the bush to point out or obtain bearings. Used on a map to measure or plot bearings. Note that some compasses have sighti