AY Honors/Map and Compass/Answer Key
This honour is similar to the NAD Orienteering Honour. This page will mainly show the answers to the different questions or where a different answer is needed. The Honour is equivalent to the New Zealand NZQA 431 Navigation in Good visibility.
Section 1 – The Map
1a. What is a topographical map?
Refer to Orienteering Honour Basically a view from on top. Symbols and colours to represent true features on the land.
1b. What is found on a topographical map?
Refer to Orienteering Honour
1c. Give three uses of a topographical map.
Refer to Orienteering Honour
2. What is an orthophoto map? Uses areal photos as the background with symbols and other information overlaid. Find a picture of one using Google.
3. Be able to recognize twenty signs and symbols found on a topographical map, giving some in each of the following categories: Most good tramping (hiking) maps will have a key showing lots of different symbols representing various features.
a. man made. eg. power poles and lines, windmills, cemetery, railway tracks, roads, 4wd tracks, walking tracks,lighthouses, mines
b. water feature. eg. swamp, mangrove, gravel bar, getty, marine farm, cold/hot spring, small stream
c. vegetation feature. eg. orchard, evergreen plantation, decidous plantation, bush, shelter belt
4. Know and explain:
a. Elevation.
1. Contour lines: Coloured orange. Points of same altitude
2. Contour interval: In the NZ old inch to a mile series 1:63360 the differnce in height between contours was 100 feet. In the new (2005) metric series 260. the interval is 20 metres.
3. Recognize nine ground formations from their contour lines. Valley, Ridge, Spur, Cliff, Saddle, Shoulder, Escarpment, Knoll, Brow
4b. Distance
This is a horizontal distance as the crow flies. It is not always a very acurate estimation of the amount of land between two points (land distance). Land distance depends on terrain. Land distance = horizontal distance + (contour interval x number of contour lines).
1. The map scale
Relationship of the horizontal distance between two points on the map and the horizontal distance on the ground in real life. This is shown as a ratio
2. Measuring map distances
Look at the map scale to calculate the real distance
4c. Map grid system.
1. What is the grid system used for?
To accurately locate reference points on a map using a set of 6 numbers.
2. Rules for reading grid references
Grid numbers are a two digit number at the end of each grid line. However a grid reference must contain 6 numbers. 3 from the horizontal and 3 from the vertical. The third digit is the approximate distance in tenths between the two nearest grid lines. Always give the longitude first then latitude.
3. Demonstrate ability to read grid system
A typical grid reference would look like 355884. Most topo maps would explain how to do this on the borders.
5. Know and Explain
a. Grid North
The direction of the North Grid lines run verticaly on the map so the top op the map would be grid north.
b. True North
Usually grid north and true north are the same on topo maps BUT in some cases this is not the case especially as the maps get closer to the artic regions. Check the map do NOT guess or assume or you will be geograhically embarrised ie. lost. Check the magnetic delination on the map.
c. Magnetic North
The direction to which the red pointer needle on the compass nearly always points. The difference between true North and magnetic North is called the magnetic declination or G-MA (Grid Magnetic Angle)
d. Declination
The compass needle alignes itself with the earths magnetic flux (lines)of force passing through the place you are standing. The difference detween true north and magetic north is the G-MA angle. This changes with the earth's magnetic field variations. The G-MA must be considered when using a compass to orientate a map. The map will give a value and time calculation so you can work the value of the angle.
Section Two – The Compass
1. What are the eight major points of the compass and their bearings?
N 0/360 deg. NE 45 deg. E 90 deg. SE 135 deg. S 180 deg. SW 225 deg. W 270 deg. NW 315 deg.
2. Become familiar with several different types of compass.
I have come to understand that there is a difference between Northern Hemisphere compasses and Southern Hemisphere compasses. I am free to be corrected on this point. It may pay to check if you are country hopping.
3. Know the parts of an orienteering compass.
4. Demonstrate your ability to:
a. Take a bearing from the map
b. Take a land bearing
c. Take a back bearing
d. Walk on a magnetic bearing
5. Resection.
a. What is resection?
Used to locate your position on a map
b. Demonstrate your ability to do a resection.
Take two or more bearings from known features. Remember to trasnfer backward for G-MA. The point where the two or more bearings cross is your location.
6. Orient your map by inspection and by compass.
Section Three – Direction without the aid of a Compass
1. Watch.
Southern Hemisphere method only.Point the 12 to the sun. Halfway between the hour hand and the 12 is North. You still have to use your intelligence for this as early morning time and evening time care must be taken as to which half you use. Eg 8am sun is rising in the East; point 12 to the sun North is halfway between the 8 and the 12 at the 10. BUT late evening the sun is heading to set in the west say time is 8pm you point the 12 at the sun. North is halfway between the 8 and the 12 at the other side of watch at the 4. This should be used only as a guide as in some countries the real time has been adjusted and sometimes there is daylight saving time etc.
2. Southern Cross.
The Southern Cross is a constellation in the Southern Hemisphere sky. The crux has a longer axis. In your mind extend this about 4 times its lenght. Find the halfway point between the Pointers (Alpha and Beta Centuri) and ake a right angle line to meet the extended line you took from the crux axis. The junction of these two lines is the SCP Southern Celestial Pole. If you were at the South Pole this would be directly above you. This is the point where the night sky revolves around. Point to this spot then lower your arm to the horizon. Where you are pointing is South.
3. Orion
4. Shadow Stick.
This method is a waste of time. We all know the sun rises in the East and sets in the West. The stick shadow shows you this. Also when the sun is at its zenith the highest it gets in the Southern Hemi look at the sun and it is towards the North the opposite in the Northern Hemi. So we learn that at mid day is the best time to find North (or South).
