maps

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=Maps = The single most important skill a navigator must have is the ability to read and use a map.

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introduction
**A map is a reduced picture of the terrain.**  The features of the terrain cannot be shown on the map exactly as they appear on the field. Therefore, “map language” is used, i.e., colours and symbols to indicate the details of the landscape on the map. As with learning or using any language, the aim should be to become //fluent// with maps: the more fluent we can become the more accurate and more detailed will be our appreciation of the area of which the map is a picture. In turn we are less likely to be lost and more likely to find features of interest.

For most outdoor activities we use //topographic// maps (which show the shape of the land).

maps for walking
(in the UK - comments about scale will apply to topographical maps from other countries)

There are 3 main options: OS maps - 1:50000 (landranger - pink) cover a larger area & 1:25000 (outdoor leisure - yellow) provide more detail. In more remote areas the latter is probably better (but if you are undertaking a long route this might entail taking lots and lots of maps, which is not good). Harvey maps are designed specifically for walking and have some features not found on OS maps. More information on Harvey maps here A key feature of Harvey maps is that they distinguish between rights of way with a path visible on the ground and those where there is no visible path.

Some "top tips" about maps:

 * 1) Unless a map is laminated or printed on waterproof paper then it must be kept dry
 * 2) But avoid hanging your map case on a string round your neck; it will blow into your face repeatedly
 * 3) <span style="font-family: Georgia,serif;">Buy a map case that is clear on the front and back; you'll be able to see twice as much as you could with one that has an opaque back
 * 4) <span style="font-family: Georgia,serif;">On a windy day it is best that at least one person in the group keeps their map in the rucksack
 * 5) <span style="font-family: Georgia,serif;">When folding a map that is printed on both surfaces, concertina it before folding in half; that way you will be able access both surfaces easily.
 * 6) <span style="font-family: Georgia,serif;">The most constant features are contours. Man-made features, including woodland, can change.

<span style="font-family: Verdana,Geneva,sans-serif;">map scales
<span style="font-family: Georgia,serif; font-size: 110%;">The determined proportion between the distance between two features on the map and the corresponding distance on the ground is called a map scale. To obtain the corresponding distance in the field, the distance on the map must be multiplied by the divider of the scale.
 * <span style="color: #000000; font-family: Georgia,serif;">Maps are scale representations of the earth. **

<span style="color: #ff0000; font-family: Georgia,serif;">**Scale is defined as the ratio between the distance measured on the map and the true distance on the ground** ( or map size:"real size").

<span style="color: #000000; font-family: Georgia,serif;"> Scale can be expressed in different ways: <span style="color: #000000; font-family: Georgia,serif;"> 1) As a ratio or fraction (e.g. 1:50000, in which case a distance on the map is the real distance/50000).[called the //representative fraction//] <span style="color: #000000; font-family: Georgia,serif;"> 2) In words (e.g."2cm to 1km") <span style="color: #000000; font-family: Georgia,serif;"> 3) With a bar scale:

<span style="font-family: Georgia,serif;">Large scale maps have more detail but cover a smaller amount of the earth (e.g. an A to Z city map). <span style="font-family: Georgia,serif;">Small scale maps cover more of the earth but include less detail (e.g. a motoring atlas).

<span style="font-family: Georgia,serif;">In the UK walkers tend to use either 1:50000 or 1:25000 maps. The 1:25000 maps include more detail and are better where route finding is more difficult/more crucial. 1:50000 and 1:25000 are equivalent to 1cm = 250m and 500m respectively ( or 4cm to the kilometre and 2cm to the kilometre).

More information about map scales map scales (MCofS)

<span style="font-family: Verdana,Geneva,sans-serif;">map symbols
We use maps rather than aerial photographs to help navigate because maps are clearer and easier to use; the use of symbols makes features more obvious - providing the meaning of the symbol is known.

Some abbreviations used in OS maps Boundaries marked on OS maps Land features on OS maps (if you think you know all about these, do you know what happens to the symbol for a pylon when an electrical line changes direction or what the differences between public buildings and ruined buildings are on maps?) OS 1 to 25000 map legend: OS 1 to 50000 map legend: OS map symbol quiz

[|map symbol]s used in USGS topo maps

<span style="font-family: Verdana,Geneva,sans-serif;">links
[|Good navigation habits] [|Map basics (BMC)] [|Map reading made easy] (OS guide) Advanced map reading made easy (OS guide): Map reading and navigation (Emergency Management Australia): For a basic introduction to maps, click here.

cartographic concepts: map reading presentation

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[|map scales] (USGS)