Orange squiggly lines

...in which we try to make sense of how height (aka elevation) is depicted on a map.

Tonight's trail run had its ups and downs, but the nub of this post was considered last night, when scanning a map for some "fast" angles onto a steep hill. I was thinking how useful I find Contour Lines on maps, but how for many people they're just really confusing. I wondered, could I explain it better than my geography teacher?

Take this example on the left. This is a section of a map showing a hilly part of Scotland, which is one of the favourite natural habitats of the Contour, represented on this map by orange squiggly lines.

Now look at the image of some circular steps below. See how they form a depression and a ridge, how each step is of a uniform height, and that it's the shapes of the steps that determine the lie of the land.


Imagine how they would look if drawn from directly above....


Hopefully, you can see the similarity. Each Contour Line is like a step, in that it's the same height along its whole length. The closer together the lines, the steeper the slope. The more lines, the higher the peak.


Obviously, unless you live in the Andean foothills, you probably won't find actual steps cut into the hillside. So what each Contour Line actually represents is the like the very tip of a step, with mud and rocks smoothing the gaps in between.

"But we did all this in school, it still doesn't mean we they make any sense to us! How to we tell which is the top, and which is the bottom?"

Look at the image of the steps again. If you were looking from directly above, then unless there was a big puddle at the bottom, there'd be no clue as to which circle of stairs was going up, and which was going down. Whereas in the map, we've got lots of clues. The first, are the orange numbers drawn on every tenth contour line, which represent height in metres above sea level.

But these numbers aren't everywhere, and they're hard to read. So how do we get an idea where the high and low points are? Look at those blue veins on the map. These are your puddles. Water will run downhill, so if you look for the water, you'll find the valleys and low spots, and normally with highspots and ridges in between.

"I still cant find the ridges - where am I looking?" See the dotted black lines that look like a chain of ants? These are established paths, since people like to walk along valleys and ridges, where the ground is less steep. If you can see a nice bumbling pathway that's out of reach of water, more often than not, it's a high-way (geddit?) and that'll pinpoint the ridgeline.

Prominent peaks often have a name, and normally a spot height (a number shown in black). That'll give you a quick clue as to whether a ridge rise or falls along its length. In the example above, there's a ridge running from northeast to south west (top right to bottom left). Sgurr Mor at 1003m translates as Big Peak, and a ridge drops gradually to the south west to little brother Sgurr Beag (Little Peak) at 890m. If you keep going, the ridge drops a little (where a path joins from the southern valley), before regaining height to the peak of An Eag at 873m.

Get yourself on a hillside with a good view, a see how the contour lines on a map correspond to the ground.

And don't be put off - the penny will drop, and you'll be surprised how much you'll be able to pick up from one quick look and a bunch of orange squiggly lines.

Tonight's run was a random bimble through Caesar's camp military training area, on some old and new trails.

Janathon Day 13: 8.3miles, 1:10hrs, 115 orange squiggly lines crossed both up and down, no ladders gone under, no pavement cracks stepped on.
Janathon total: 113miles. You can view all my maps and stats here.