In this first part of a how-to series on cross-country navigation we will look at how to bring maps to life in order to get the most from them on your outdoor adventures. Future articles will then focus on using a compass and more intermediate-level navigation skills.
The Power & Intrigue of a Map
Empowerment / discovery…
Types of Maps
There are several types of map and you have probably had experience with using more maps
then you think. Consider the list below:
- Topographic Maps – most common type for outdoor adventure activities;
- Sea Charts / Nautical Maps – used for boating and sea kayaking;
- Street Maps – source of great tension between men and women;
- Tourist Maps – contain information relevant to sightseeing;
- National Park / Trail Maps – contain relevant recreational trails and information,
- as well as some normal topographical information;
- Cadastral Maps – show land boundaries and ownership;
- Topographic Image maps – combination of normal topographic information
- overlayed on an aerial photograph;
- Mud maps / sketch maps – not to scale, but containing the most useful
- information only. We have probably all used and even drawn this most common
- type of map;
- Geological, vegetation, mining and other maps showing specific information.
For most outdoor adventure activities on land that are self-propelled, Topographic Maps are the map of choice. My working definition of a topographic map is that it is “a to-scale, 2- dimensional representation of the lay of the land and it features, both natural and man-made”.
From my experience of teaching people how to read maps I have often noticed that the people who learn map-reading easiest are people who are also good at art or graphical drawing. Once all the map terminology and conventions are learnt, reading a map is simply about transferring the 3-dimensional word to a 2 dimensional piece of paper and vice versa.
Map Errors and Inaccuracies
Blaming the map for getting lost is like a bad tradesman blaming their tools. There are however a number of ways that maps can contain errors. These are not to be used as excuses if you become disoriented, but rather for map users to remain aware of. There are two main ways that maps can contain errors and inaccuracies:
Age of maps. When using a new map for the first time always check the year that it’s information was collected. For most topographic maps the most relevant year will be when the aerial photography was completed. In regional areas of Australia (for example, Cairns), aerial photography hasn’t been updated for maps since 1978. In almost 30 years a lot of things can change: what was marked on the map as a field of sugar cane may contain a new subdivision or a 4-lane highway that wasn’t marked on the map. Conversely, an old logging road in a rainforest area that doesn’t get used anymore can quite easily overgrow within 10 years to a point where the road cannot even be found anymore – even though it is marked on the map.
Map production errors. As most maps are made from aerial photography data, occasionally translation errors may occur. These errors are more common in heavily forested, remote areas. The errors which occur here seem completely illogical and include creeks being shown on the map when they are not there in real life and vice versa. Errors in built up areas are rare due to extensive field-verification procedures.
Also, in areas of extremely dense vegetation (e.g. rainforest), the steepness of the terrain is often shown as less on the map than it is in real life. This is because the aerial photography process makes are prediction on the land shape based on what the tops of the trees are doing. In many of these such areas trees grown taller in the sheltered, moist gullies and shorter on the more exposed spurs and ridges.
Common Australian map scales for bushwalking and navigation sports
Measuring Distance on a Map
There are a number of ways to measure distance accurately on a map. If you intend on following a bearing to walk a straight line between two points, you can easily measure the distance with a ruler, the long edge of a compass or the side of a romer device. You can even put a blank piece of paper along you intended path, mark the start and end point and then measure these marks against the scale line in the map legend. Of course we don’t always walk in straight lines in the bush so the ability to measure distance around corners is crucial.
One way do this is with a piece of string (or compass neck cord) to trace out your intended route. After tracing out your route, pull the string straight and measure it against the scale line in the map legend. Alternatively, there are several commercial map measurers available such as those below, with some compasses even having built in map measures. All of these devices incorporate a wheel that you move along you intended route. You then (either manually or digitally) convert this map distance to real life distance using the appropriate scale calculation.
Looking After and Using Maps
A map is of no use unless you read it often. Rolling a map will definitely protect it, but it will be of no use in the rolled form. Additionally, if you can’t access your map easily you probably won’t (or at least not as often as your should) thereby leading to more moments of geographical embarrassment. There are several commercially available map cases which are see-through and waterproof, allowing you to fold your map so that the relevant section is visible. These can also hand around your neck or attach to a backpack. A plastic A4-size insert pocket sealed with tape is a cheap alternative for use over shorter durations.
Navigation sports such as rogaining and orienteering necessitate that the map is looked at frequently and is thus often held in the hand. Maps for these events can be trimmed to a minimum size and then covered in contact (plastic adhesive book covering).
Maps getting wet often could even be laminated once the desired part of the map is chosen. When laminating ask for 40 micron (40 millionths of a meter) as opposed to 80 micron thickness laminate as it is much easier to use and can be folded more readily.
Where to Buy Maps
Geoscience Australia produces paper topographic maps at scales of 1:100 000, 1:250 000 and 1:1 million. For many years, these topographic maps, or NATMAPs as they are commonly known, have provided Australians with the information they need to navigate and explore this vast continent. In conjunction with the Department of Defence, Geoscience Australia produces more than 2000 different topographic map titles. All of these maps are available through Geoscience Australia, which also distributes the Department of Defence’s 1:50 000 scale topographic map series for northern Australia. Many other scales of topographic maps are produced for popular National Park and other protected recreational areas.
Maps can be purchased through the Geoscience Australia website: www.ga.gov.au, from your state’s government land management agency, from specialist chart and map shops and sometimes from outdoor equipment stores.
Digital Topographic Maps
Geoscience Australia has identified a growing market demand for digital versions of its paper map products. Digital maps are just that, digital versions of the map. They are an image of the map and not the digital data that the maps are produced from. There are also companies that manipulate this digital data and offer software to enable users to print their own maps and integrate with GPS units. Some of the more popular mapping software includes Memory Map: www.maptrax.com.au, Fugawi: www.fugawi.com, and OziExplorer: www.oziexplorer.com.
Map Marginal Information and Legend
This is all of the information contained around the edges of the map and in the legend. The legend information can be broken into distinct sections which are colour-coded.
- Topographical (contour lines) – Brown;
- Vegetation – Green;
- Glaciers / Snowfields – White. This colour also depicts areas of little or no vegetation;
- Surface Features (Roads) – Red;
- Surface Features (Buildings) – Black;
- Rivers, Lakes and Canals – Blue;
- Features added since original map survey – Purple.
10 things to look for on a map when using it for the first time
- Map name.
- Age of map.
- Map datum (if using map with a GPS).
- Map scale.
- Distance scale.
- Contour interval.
- Map sheet number and index to adjoining maps.
- Water, rainfall and temperature guides.
- Magnetic declination / grid-magnetic angle.
- Any extra symbols you may not be familiar with, both natural and man-made.
Grid references are used to give a specific location on a topographic map. There can be 4-, 6- or 8- or 10-digit grid references, however 6-digit are most common for general outdoor use They should have “GR” written before the number, otherwise it could be just a phone number. A grid reference should also given with map name and scale (or map sheet number) when quoting a location.
Grid references utilise the map grid drawn on the map (grid lines). Grid lines have numbers on the map borders and on the map itself, from 0 to 99 then repeating from 0. The vertical grid lines are called eastings, because the numbers on these lines get larger as you go east. The horizontal grid lines are called northings because the numbers on these lines get larger as you go north. The Australian map grid is consistent across all topographic maps of different scales and represent 1 square km of land per grid square.
To give the location of point A in the diagram below, we look at the grid square that the point is located in. It is customary to give the easting component of the grid reference before the northing component – a simple way of remembering this is that E comes before N in the alphabet. We see that A is located between the eastings numbered 23 and 24. We always give the lower number, in this case being 23. The northing competent for the point A is 47, therefore we write point A’s location like so: GR 2347. This narrows our location down to an area of land 1km by 1km, which is a little too big an area for most practical navigation.
To get more accurate we need to give a 6-digit Grid Reference. The first two numbers of both the easting and northing components are found in the same way. For point B below we could write GR 21x45x. To get the missing x’s we divide each grid into tenths in each direction and estimate how many tenths the location is between the lower and higher grid line numbers. Point B would therefore be GR 216458. If you are in doubt as to whether a point is xx3 or xx6, round down (this is called the south-west convention). A 6-digit grid reference narrows our location down to an area of land 100m by 100m, being a hectare. For most outdoor recreational activities this level of accuracy is sufficient.
Another way or remembering which part of the grid reference to find first is the simple rhyme – “you need to walk across the page before you can climb up the page”, meaning that you walk across the page and find the easting first, before climbing up the page to determine the northing component. This method works even if you forget what the eastings and northings are.
What is a Romer?
A romer is a simple device for accurately plotting a Grid Reference on a map. Essentially, it is a specially marked out ruler which matches the scale of the map in use. The romer featured below, available from Geoscience Australia (www.ga.gov.au), also has scale rulers for the most common map scales and a compass rose for calculating bearings.
Using a Romer to Help Plot Grid References
The scales are laid out in reverse such that by lining up the numbers given in the grid
reference with the gridlines for the square in question, the corner of the romer lies on the
referenced spot. A small hole at this point allows the location to be marked with a pencil. In
the picture below, the corner of the romer is placed upon a particular bend in a creek. The
easting component of the grid reference would be 327 (the number “7” being the point at
which the romer crosses the easting line with the lower number. The northing component
would therefore by 978, making the 6-figure grid reference GR 327978.
Contour lines are used to represent a 3-dimensional landscape on a 2-dimensional map. A contour line is a line joining points of equal height above sea level. Perhaps for weather buffs a useful analogy for contours are isobars on a weather map: isobars join points of equal air pressure. The following diagram depicts a simplification of how contour lines on a map are created. In this example the “Contour Interval” is 10m, meaning that the contour lines are 10m apart, vertically.
The shape, number and spacing of contours vary to show a myriad of different landscape. Some common features and their contour patterns are:
- Steep slopes – contours that are closely spaced;
- Gentle slopes – contours that are less closely spaced;
- Gullies / Valleys – contours that form a v-shape pointing up the hill. The V’s are
- always an indication of the drainage path which could also be a creek or river;
- Spurs / Ridges – contours that form a v-shape pointing downhill;
- Summits / knolls – contours that form circles.
The most common contour features are identified below as they appear on a topographic map.
5 Ways to Improve Your Map Reading Skills
- Buy some maps – Purchase some topographic maps of your home area as well as areas that you often visit for recreational purposes. Look at them often (perhaps place them on your office desk or dining table) and practice finding things and features that you know in real life on the map.
- Read some books – Re-read this article, as well as other navigation reference texts as outlined in this article. Do some internet surfing also to see what you can find in relation to map reading.
- Do a navigation event – Participate in an orienteering or rogaining event. Both of these sports also feature metropolitan events where maps used are similar to street directories with the street names removed.
- Take a hike – Go for a bushwalk, but take a map this time. Even if your walk is along marked tracks, use you map reading skills to keep track of exactly where you are at any given point.
- Go geocaching – Although a GPS is needed to find many geocaches, you can look for caches in your local area as the geocaching website also contains a Grid Reference (UTM) for each cache. Assuming that you have the relevant topographic map, use the clues provided to narrow in on the find.
Navigation Event and Association Websites:
- The Australian Rogaining Association is the peak body for Rogaining in Australia. Relevant state rogaining associations can be accessed from this site. www.rogaine.asn.au
- Wilderness Rescue Navigation Shield – Overnight Navigation Event www.bwrs.org.au/navshield/
- Polaris Endurance Navigation Events – Mountain Bike, Paddle and Urban Events. www.wildhorizons.com.au
- Geocaching – World-wide treasure hunting using a GPS and other navigation skills. www.geocaching.com, or www.geocaching.com.au.
- Orienteering Australia – Main organisation for orienteering in Australia. Relevant state orienteering associations can be accessed from this site. www.orienteering.asn.au
Navigation Instruction Websites:
- Learn Orienteering Site by Kjetil Kjernsmo, Norway
- Maps & Compasses site by the Department of Education & the Arts, Queensland. http://education.qld.gov.au/curriculum/area/maths/compass/index.html
- MapZone Site by Ordnance Survey, UK.
- Rogaining: Cross-Country Navigation, Now the third edition of this classic from the founders of the sport, Neil and Rod Phillips. Copies of this book may be obtained from the publishers: Outdoor Recreation in Australia, Box 3 Central Park Vic 3145 Australia
- Advanced Outdoor Navigation: Basics and Beyond, by Greg Davenport, 2006
- Which Way’s North, An informative introductory booklet for rogaining produced by the Victorian Rogaining Association. Visit www.vra.rogaine.asn.au to download a .pdf copy.
- Exploring the Nature with a Map and Compass, SISU Sport Books, 1999.
- Map Reading Guide, by Geoscience Australia, 2005. Downloadable in .pdf format from www.ga.gov.au.
- Map Reading Handbook, by Tasmanian State Emergency Service, 1997.
Darren Osmond has been navigating cross-country for 15 years. Since childhood he has undertaken many challenging off-track bushwalking expeditions. He began competing in rogaines in South-East Queensland and then moved to Cairns and has been coordinating rogaining activities there since 2000. His navigation skills enabled him to compete successfully in several adventure racing events, including New Zealand’s challenging Southern Traverse in 2002. In a professional capacity, Darren taught navigation and other outdoor recreation subjects at Cairns TAFE for 7 years and also runs cross-country navigation training courses at all levels for the general public, as well as training people competing in expedition length adventure races such as the Eco-Challenge and the XPD.