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The Basics What is a map? A map is an artists impression of the landscape, a drawing of what is around you (see this example - Kirklevington from the air). There are many types of map, they could be an 'A to Z' map that is concerned with streets in a town, it could be an 'Ordnance Survey' map concerned with small areas of the country (about 30 by 40km square or 60 by 80km) or a road map (or atlas) covering the whole country. Other maps you may encounter could include hand drawn sketches and a type called a strip map. All these maps are valid and good for the purposes they are made for. To distinguish between these different level of details maps have different Scales. The scale of the map refers to the proportion between a measured distance on the map and the distance it represents in reality. For example a scale of 1:25000 means that 1cm on the map represents 25,000cm in reality (250m or 1/4km). In a Scouting situation with walking or cycling expeditions we concern ourselves mainly with 1:50000 and 1:25000 scale maps. Ordnance survey has surveyed the whole country and produce a map to cover each part of the country. From now on in this document I will be writing as if you are going to use an Ordnance Survey map (or OS map). A bit about why you use a map A map can be a very useful thing and it is used mostly for finding your way about. You would look in a street map to find a road you want to go along or a road atlas to go on a car journey where you have never been before. You can use the map to identify where you are, for example 'I am by the church' and from there work out where you want to go. The other use is in surveying the land, where boundaries are between properties etc which is useful for builders. They have many uses but the main one is finding your way about. What can I see on a map? Since a map is basically a drawing, features on the landscape can be drawn as symbols instead of an accurately drawing the feature and this makes these features easier to identify (for example a church might be represented by a '+' symbol). There are many types of symbols on the map. Many of these are things you could readily identify and use this place as a point of reference, for example 'I am by the church shown on the map'. These places might include features such as Police stations, places of worship, car park or telephones. Each of these are located at a point. There are some symbols that represent an area on the map, for example a golf course, campsite or army firing range. It is more tricky to use these to pin point where you are since they cover a wide area, for example 'I am on the golf course shown on the map' doesn't say whether you are in the club house or just halfway round the course. Other features on the map are linear features, such as roads, power lines or fences. These are generally highly visible and obvious but like symbols that represent an area on the map don't really help pin point where you are. If you are near where 2 of these features interact then you can use this, for example 'I am at the level crossing' or 'Turn left at the road junction'. Some features you can't see on the ground are Contour lines, Grid Lines, country or national boundaries. Contour lines and grid lines are the 2 most useful of these. Contour lines join places of equal height above sea level and can give an indication of if the ground is sloping, whether you want to go up hill or down and how steep the slope is. They show the shape of the land. Grid lines are imaginary and made up for the map. Each map is divided into squares representing 1km and this distance is marked by a set of vertical (eastings) and Horizontal (Northings) lines making a grid laid over the map. To check your knowledge of map symbols you can look at the 'Key' on a map which shows all the symbols used. Look at symbols on the map and say what they are and then check using the key Describing where you are on a map One of the reasons to use a map is navigating around the country. To do this you might need to be able to describe where you are and where you want to go to, or have someone else describe to you where you want to go or be. You can describe where you are in words 'Go to St. Mary's Church' but in many cases there are no easily identifiable places to say where to go. There is another method and that uses one of the imaginary features drawn on the map. On the map there are a set of imaginary Grid lines. These run Horizontally (Northings) and Vertically (Eastings) and each line is numbered between 00 and 99. The distance between these lines represents 1 kilometre (1000 meters). Every 100 lines the numbers repeat. ordnance Survey has split the country into 100km squares and given each of these letter to represent them. Since we are unlikely to be walking 100km. we will ignore these letters for now. You can use the grid lines to describe the co-ordinate where you are on the map, this co-ordinate is referred to as a Grid Reference. In the simplest form this is a 4 digit number, the first 2 digits is the number for the easting to the left of your point and the second 2 digits refer to the northing below your point. For example Grid reference 4309 suggests to look in the square boarded by vertical grid lines 43 and 44 and the horizontal ones 09 and 10. This is a huge area (1km by 1km) and this can be broken into smaller areas to give a more accurate description of where you are. To give a more accurate description of where you are you could say 'I am in Grid Square 4309, near line 43 and nearly at the line 10 - you are in the top left quarter of the square. Using this idea of splitting the grid squares in half, we could divide it into 10 lines going up and 10 going across. Now all you do is to 'guess' which tenth across and up your point is and add that to your grid reference. For example, as before we were near line 43 and nearly at the line 10 of grid reference 4309. Near line 43 could be about 2 tenths across from line 43, and nearly at line 10 is 9 tenths from line 09. Well add this to our grid reference - 43 and 2 tenths across, 09 and 9 tenths up. We can make this neater by removing the words to get 432 across and 099 up or - 432099. Try this on the map and pick some points and try and work out the grid references, or look at this grid reference reading check to see if you are doing it right. Can you find where 432099 is? A Simple mnemonic to help you remember the order of a grid reference is: "Through the Door, then Up the Stairs" It is often useful to add a description of the grid reference as a double check, for example 'Grid Reference 332059, near the A167 Road', the double check in case you gets the grid reference wrong. Navigating Using the Map You can be given a list of Grid References as a route to follow and you can find these on a map. To Navigate using a map and grid references you need to find the 2 points you are going to walk between (if your route has more than 2 points, concern yourself with only the 2 that your walking between). Locate these points on the map and then look at how to get from one to the other, use the map symbols to show you what the land will be like, for example are the points connected by a path, bridleway or road? Do you have to walk through a wood or cross a river or go through a town? Is the point you are walking towards a notable feature on the map, for example a church, a road T junction etc. Bear in mind the invisible contour lines that suggest the shape of the land and steep hills, do you want to climb over a steep hill or just go round it? It is often best to stick to tracks, footpaths and roads rather than walk cross country Now look at the actual landscape around you, can you identify any of the features you saw on the map? Which side of the feature do you walk around it, for example if you walk beside a wall, is it on your left or your right? Try to relate the map to what you can see. You might not be able to see your destination but you might see something halfway between the 2 to walk between. As you walk towards your destination keep a mental note of the features you identified and note as you pass them, for example if you are passing 4 small streams count them as you go and if you pass a 5th one you might have gone too far. A good indicator of which way to go is the compass bearing The Compass A compass is a magnetised needle that points to magnetic north. You can use a compass to measure a bearing. A bearing is a measure of a direction and is the angle between the direction you want to measure and north. A bearing is a number between 0o and 360o, where 0o and 360o represent North, 90o for East, 180o for south and 270o is west. You can combine the bearing and information on a map to help you navigate. Using a compass is useful if you can't use other indicators of where to go, for example in poor visibility or at night. Apart from using a compass, there are other method of finding north which you can find out about, for example using a watch, a moon compass, or using the stars or sun. Now what? The best way you can learn all this information is to actually look at a map and try to figure out what I meant. Pick points on the map and describe what the symbols mean. Work out the grid reference for the point. Pick another point and describe what it is and its grid reference. Now look at a line between these 2 points and describe what features are between the points. Now look and try to pick a rout to connect the 2 points. Now go out on the hills and do this for real in good weather then in the wind and rain and if you don't get lost and die then I guess you have understood |
