Maps are essential when it comes to navigating in unfamiliar or dangerous terrain, and if we don’t look after them we can put ourselves and others at great risk. This article will briefly introduce the concept of what a map is, some of the forms modern maps come in, and outline some things you should do to look after your map.
In a day of GPS digital devices there are many great products and apps out there to assist with navigation, we use the app FATMAP for sharing, planning and tracking all of our routes, but what do you do if the device you are using fails? This is why it is always important to carry a map and compass, and have at least some basic map reading skills, We here at Thru-hike Adventures feel passionately about map reading and the ability to navigate yourself, in any conditions, this is why we will be posting regular blogs to help you brush up or gain new navigational skills, if you would like to then put these skills to practice then why not come along to one of our navigation weekends, Our Find Your Way Scheme sees us offer free navigation lessons to anyone under the age of 16, if you represent a school, youth club or any kind of organisation please get in touch to find out about our free for kids map reading summer events.
Maps & Map Scales
Here in the United Kingdom it is the Ordinance Survey (OS) is the national mapping agency for Great Britain. The agency's name indicates its original military purpose, which was to map Scotland in the wake of the Jacobite rising of 1745. There was also a more general and nationwide need in light of the potential threat of invasion during the Napoleonic Wars.
Chances are you would have already come across one of the many thousands of Trig Points or trigonometrical Point (little concrete pillars you usually find dotted across the high points of the UK), these are from the retriangulation of Great Britain projects carried out between 1935 and 1962 that sought to improve the accuracy of maps made of Great Britain.Data gathered from the retriangulation replaced data gathered during the Principal Triangulation of Great Britain, which had been performed between 1783 and 1851, when the age of GPS came along, most of it was accurate anyway, that shows the incredible job the engineers did all those years before with just some basic tools and some amazing brains, we will cover the Ordinance Survey and Trig Points in more detail in a future blog post.
All maps are drawn to scale, the most common we work with being 1:50000 and 1:25000, but what do these numbers mean? Well, a map scale is essentially a ratio. On a 1:50,000 (one to fifty thousand) scale map, each centimetre (cm) on the map equates to 50,000 cm of actual terrain. An easier way to put this into perspective is 1 cm is 500m, so 1 kilometre (km) on the map, will be represented by 2 cm. The scale of a map we chose for our activity will reflect the nature of activity we want to do; driving 50 miles we are unlikely to need the accuracy of a 1:50000 map, but a 1:250000 road map may be more suitable, and equally using a road map to hike the Brecon Beacons would be unadvisable.
Here’s a table of some common scales and their uses:
While we would strive to carry a map that contains as much information as possible, this would mean to cover the same area we would need as many as 2 or 4 times as may maps, especially for multi-day hiking routes or cycling tours. Have a look at how some of the different scales of maps may look. Notice how the levels of information contained within them also changes
the size of grid square also changes depending on the map you use. A 1 cm square on a 1:50,000 map covers an area of 1 square kilometre, but this doubles to 2 cm squares for the same area on a 1:25,000 map. As a rule of thumb, the diagonal distance across a grid square is 1.5 km. The same map area sees an increase of 4 times, resulting in more detailed information, but also the need to carry more maps for the same area.
Side by side, we can see the differences between the 1:25,000 and 1:50,000 maps.
The two main map products from Ordnance Survey are their Explorer (1:25,000) and Landranger (1:50,000) map series. Each sheet has a name, but also a sheet number. In the example image these are the “Explorer OL2” and “Landranger 110” maps. Each sheet number is part of the larger national grid system in which every part of the country is covered. This grid system is shown below. You can also find maps for your
8own area using their map finder tool.
Folding a Map
This is an art! But it shouldn’t be complicated. Thankfully most maps we buy will already be folded, but there may be times where we actually want to re-fold a map to reflect an area we will be working in. We’ll start with a fresh map that hasn’t been folded before.
surface – the floor or a large table.
Work out what way you want to fold the map. It is easiest to create the first fold horizontally.
Fold the map in half, long ways. This will present the map information to the front, and the blank side folded in on itself (unless you have a double sided map, then you will need to chose which side you want to use first).
Now think about folding the map again, this time short ways.
With the map folded into quarters, unfold the end and line it up with the edge.
Now repeat the folds until you have created a concertina.
You can now open and close the map folds, remembering to flip the map over to see the information contained on the back.
Map Rules, here some basic pointers when dealing with maps. These are to ensure the integrity of any information on the map and to make sure you get long life out of your valuable maps.
Don’t rely on digital maps and GPS. Batteries die, and signal can be lost. Always carry a well protected, properly folded paper backup with a compass.
Never draw or write directly onto a map. If you must, then use a light pencil that can be erased later.
When working outdoors, always use a map cover or case. This will protect the map from adverse weather conditions and grubby fingers.
Never cut a map, you never know when you will need the information you destroy.
Protect and look after your map. Sometimes it can be your only way out of trouble.
And finally, know how to use your map. As you develop your knowledge you will soon become more comfortable reading a map and using it for navigation. By reading this article you have now taken your first step into knowing how to use your map.
Look out for the next blog post in this navigation series where we will cover the basics of how to read a map.