Maps and Map Reading

Maps and Map ReadingThis information is aimed at helping the competitors on Chasetrek to obtain a basic understanding of how to use a map. Since the event is staged in the UK, the map symbols used reflect those on UK maps. This document can be freely copied by any none profit organisation, providing that the source "Tony Field of Chasetrek" is quoted.

This tutorial forms part of a set of information, which includes, some basics of map reading, how to use a map and compass together, some tips on how to avoid getting lost and finally some online questions.

Compass Tutorial  Navigation Tutorial Hints on not getting lost! Online questions

Map Scale
Maps are two dimension representations of three dimensional features. They are drawn to a scale which is printed on the map. Scales such as 1 to 50,000 mean that an object measuring 1 cm on the map will be 50,000 times one cm in real life, or 0.5km.

However since maps are presentations they also use symbols to represent items. These symbols shown later on are not to scale. Thus the symbol for a church is a  + The size of the cross does not represent how big the church is only that it is there.
Contour Lines(thanks to Doug Latimer)

A contour line is continuous line of the same elevation (or height) around the edge of a feature. Think of it as the edging trim along each layer of a wedding cake. Each line gives an outline of what a feature looks like at regular intervals of elevation. The closer together the lines are, the steeper the slope. For example the close gathering of contour lines on Mt. Wrongagain represents a steep slope. The spread out contour lines indicate a more gentle slope. UK map contour lines are at 10 meter intervals (Although they used to be at 50 foot intervals), that is each line represents an outline of the mountain 10 meters higher than the line below it. Contour intervals will vary with maps, and it is important to check the interval to interpret the map.On UK maps contour lines are printed in Brown, with every 5th line thicker. This line will carry a number somewhere along it's length which tells you the height. The intermediate lines you have to work out for your self. (see below)

To understand the shape of the mountain it is helpful to use the contour lines to build an image of the feature, either in your mind or to draft out a profile on paper. Here is a profile of Mt.Wrongagain.

The mountain has two peaks, with the higher summit on the left. The lower slopes are moderate, becoming very steep towards the summits.  Because the contour lines are at 50 foot intervals we can only estimate what the terrain between each contour looks like. An 40 foot cliff could easily hide between contours and not be recorded on the map. With this in mind it is good to remember that while these maps are generally very good, there is still room for the odd surprise.

One of the most difficult things to interpret on a contour map is a sense of elevation, ridges, and valleys. Here are a few tips. Water always flows down through valleys or gullies, never ridges.
 

Creeks begin at higher elevations and flow down to lower elevations where they join to form larger but fewer rivers. When contours form a bulge that points from a lower elevation to a higher elevation, it is a gully, valley, or bowl. When contours form a bulge from higher elevations to lower elevations it is a ridge.

Grid Lines andGrid References

On UK Ordinance Survey maps there are two sets of parallel lines which mark the grid lines. These lines are in black and run vertically and horizontally on the map. They represent 1 km squares and enable people to accurately give a position of a place. On the side of the map are a set of numbers (know as Northings) which number each of the horizontal grid lines. On the top and bottom of the map are another set of numbers (known as Eastings), which number each of the vertical grid lines.To make a grid reference, follow the vertical line to the left of the chosen location down to the foot of the map to read it's Easting - for example 04. Then estimate the number of tenths from the grid line to the location - in this case 5. Therefore the first part of the grid reference is 045. Repeat this with the horizontal grid line just below the location (410). The full six figure grid reference is therefore 045410.

TIP. How to remember which numbers go first. There are loads of saying and methods, but here are three

1. Just learn that the Eastings go first followed by the Northings
2. "along the corridor and up the stairs"
3. "walk along the flat before you fly upwards"

Map Symbols
The only map symbols shown below are those that are likely to be found on Cannock Chase UK. They are sourced from the ordnance survey maps (1:50,000 series). There are some differences between the 1:50,000 series and the 'Explorer 6' map of Cannock Chase, which many find easier to use. © Crown Copyright MC 99/346
Competitors on Chasetrek should know all the following if they are to correctly navigate the route.

Roads and Paths

Railways

Land and water

Buildings and Objects

Did you know?

• The word MAP comes from the latin word, Mappa and means napkin, cloth or sheet.
• The First map to represent the known world was created by Anaximander, a Greek philosopher in the 6th century BC.
• A cartographer is a person who creates maps.
• A map on a spherical surface is called a globe