I'm preparing a hint sheet for young competitive orienteers who rarely come across the need to understand contour lines. They live and compete in SW Florida where most contour lines are 'negative' and surround ponds and the highest points of land are old garbage dumps and highway over passes. They get totally confused by contour lines when they get to competitions in Georgia.
Next month some 400 of them will be competing in one of the few significantly contoured areas in Florida. I'd like to help them understand up from down before they get there. For sure I'm pointing their leaders and instructors to the many resources on line that explain contours but those don't seem to cover how to tell up from down in all situations.
So far I've collected:
Contour tags - always on the down side of the contour line
but if there are no tags
Streams - they flow down hill and if they go through a V in the contour the V is pointing up hoill
But if there is no stream (and there aren't any in this sandy terrain)
Small closed contours - these are at the top of the hills usually (and if they are at the bottom they must have a tag)
but if these are not easy to find
Vegetation - in this area the thicker vegetation (Green on the map) is usually in the lowland where there is more water and rough open trees are at the higher bits of land. (I stress in this area as I know it does not work everywhere)
That is my guide so far. Are there any other hints/ clues that you would suggest I impart?
Contour tags always point down hill, but they are rare, small, and hard to see. Water is your biggest hint. Ponds at the bottom; creeks in the valleys. Brown loops that have water in them are a bottom; brown loops with no water means it is a hill top. On top, the browns lines will be gentle curves; in valleys, contours have sharp V-shaped turns where ditches and gullies form. Generalizations about vegetation at the bottom may not be true in all cases.
I think you’ll need a bit more clarification about the V pointing uphill. Will the hint sheet come with sketches?
In areas with significant relief, spurs tend to be broad and rounded, reentrants tend to be more narrow and pointed, if the land was shaped by flowing water, even if the water is no longer there. It's not a hard and fast rule, but I think most experienced orienteers subconsciously apply this when looking at a scalloped contour line. If you're going to someplace like Wekiwa Springs, this will be hard to notice, but it should be pretty pronounced on most maps in Georgia.
Take them out to play in a sandpit. Or invest in Play-Doh.
Genuinely. Once they've built a few different landscapes and then 'mapped' them, it'll all start to make sense. Use cocktail sticks or similar to mark points of equal height, then join the dots to make contour lines.
We used to do this on mountainsides using people instead of cocktail sticks, but this will cause problems since:
1/ you don't seem to have mountains
2/ as well as learning about contours, we all got very very cold and wet.
IMO a lot of wordy instructions are a bit daunting (it's the same with compasswork) but I do get why a simple crib sheet could help.
I use the "back of hand" map - I learned that way back as a kid, water flows in the "valleys" between the fingers, not on top. When flattening the hand one has sharper "V" and wider "U" shaped sets of contour "cups", with Vs and Us pointing in opposite directions. If it were to pour, rain water would flow "out" of the V shaped cups and not into, and definitely not flow through the Us.
Again wordy, but if showing using one's own hand, has worked really well for me.
Agreed with Cristina about which way the "v" "points". That can be confusing. I liken the "V" to a water cup (grab a cup, preferably one of the pointy ones that are used with some water coolers, for illustration if you are presenting in person - if you really want to get elaborate, bring a second cup, sliced in half vertically.) Show how the cup is turned on its side. The cut edge represents the contour, water flows down and out the mouth of the "v".
Thanks for all the advice.
The explanation will be written by way of competition notes sent out to the team leaders a week before the event - only a week before because that is when they get back from the Christmas break.
I'll drop the stream/ V idea because of your advice but also because there are no streams flowing down hills there. In that part of Florida, like everywhere in Florida it rains a lot but the rainwater just soaks in to the soil. You only find run-off where roads have compacted the soil - amazing!
But the objective is not to teach about contours. It is to teach how to recognize up from down while on course, on the run. Of course there is the Hunter Method - 1) I'll figure it out when I get there. 2) It doesn't matter whether it is steep up or steep down, if it is steep I want to avoid it.
In Georgia, "towards water is down" should generally work.
Also, this can be taken for granted, but always good to remember that if you're crossing contour lines then you are either going up or down (and if you're going up or down then you are crossing contour lines). If you don't want to cross contours than you have to stay mostly flat.
Contours closer together == steeper.
Don't underestimate the importance of stressing that they will not see those lines on the ground. I've done course reviews with kids that I was sure knew better who had spent time in the terrain looking for the feature that matched an index contour, or followed something that they thought was the contour on the map.
I also think your Hunter method number (1) is important. When you know where you are, take a look at what's up and down. And don't forget that you might have mixed it up. If you think you're running towards a big spur and all of sudden there's a gully in front of you, you probably got it backwards.
This discussion thread is closed.