When you talk to someone about maps, they usually think of paper maps. Paper maps are great (though they have limitations, which we’ll look at later). Of course, most maps are actually digital these days, and for valid reasons.
What stories?
When a map has any way – be that shading, or contour lines – of telling you about the undulating landscape, even if that map has nothing else on it, it’s of use. You see, the moment you can see where the hills, or mountains are, you can also see where the valleys are.
When you can see where the valleys are, you can see where the water flows. That, in turn, means you can see where the streams and rivers will be. Once you know that, you know where people will be. In fact, a large number of settlements form where two rivers flow into one.
That’s just one example of the stories hidden in maps, but there are many more.
Contour lines made easy
Have you ever played Minecraft, or seen anyone play the game? If not, have a look at the video below:
You will see that in Minecraft, the world is made from blocks. Those blocks are stacked in different layers, to create an undulating terrain. If you were to trace lines along the edges of all the blocks on each layer, effectively, you’ll end up with contour lines.
An interactive map
Contour lines are imaginary lines that show how high above sea level any place on a map is. If you followed this link, a new browser tab will open, showing an Open Street Map topographical (or contour) map, centred on the Erme valley.
Within that map, you will see the contour lines, as jiggly lines. The darker contour lines are major height markers – in this case, 400 metres above sea level. The lighter contour lines mark 10 metre elevation intervals. If you walked along a contour line, your route will be neither uphill, nor downhill.
The closer contour lines are to each other, the steeper the incline is. Think about that: if moving from one contour line to the next gains you 10 metres elevation, what determines the gradient is the distance between the two contour lines. If the distance was 200 metres between them, it means you’d gain 10 metres elevation for 200 metres travel. That’s quite a mild gradient. If, however, the distance between the contour lines were just 10 metres, the gradient would be 45 degrees, which is steep.
Why do contours matter?
At the most basic, contour lines tell us where is high ground, and where is low ground. As you’ve seen, they also tell us the gradient, which is far more important than you might think. For starters, rivers flow slowly and serenely over flat landscapes, but they turn into white-water torrents, down steep gradients.
Most villages, towns and cities have been in the same location for a very long time. That location, in the vast majority of cases, was determined by the availability of water. Water if life, and in medieval (or earlier) times, people used to get their water from rivers. Contours determine where the rivers flow, and they also determine where the river might be narrow enough to bridge.
As a result, contour lines influence travel options, and therefore roads. The French discovered this a very long time ago, and so many of their mountain passes are reached by roads carefully constructed to have a steady 6% or 7% incline. Most roads tend to follow very old routes, and those routes were influenced by the ability to bridge rivers. It’s only quite recent, in humanity’s existence, that we developed the ability to build large bridges, to span huge gaps.
Types of maps
Earlier, I said that paper maps – no matter how much I love them – have limitations. That starts with the scale of the map, which is fixed. A map scale determines how much detail a map can show – for cross-country hiking, you want a 1:25 000 scale map.
Aside from the obvious – the fixed scale – paper maps have other limitations. Digital maps carry metadata – extra information that isn’t immediately visible, but is relevant. For example, when you go plot a cycling, or hiking route on the very best website for that, RideWithGPS.com, the train will be solid, when on a tarred road, but turn to a dotted line, when unsurfaced.
There are many more examples of metadata, including the heatmap on RideWithGPS, which instantly shows how popular a particular stretch of route is. If it isn’t popular (especially for cycling on the road) then it’s likely that most cyclists think of that stretch of road as too dangerous. Other examples of metadata include the oodles of additional information I embed in the digital GoCycle multi-day cycle touring route guides I create.
What does this matter to me?
If you go exploring (and you really should!) either on foot, or by bicycle, understanding the stories maps tell will help you understand the landscape better. It will help you avoid enormous hills (should you want to) or tackle enormous hills (if that’s what you’re after).
Being able to read the stories hidden in maps will enable you to plan far better adventures, too.