Map Reading: Contour Lines
Maps are flat… trails are not!
Ever wonder what all those winding brown (red-ish brown) lines on a map are? They are contour linesand they are drawn along areas of shared elevation. A functional understanding of contour lines can help you scout out your hike before you even head out your front door!
The key takeaways for this article are as follows:
1) When a trail meanders parallel to, or, within two contour lines, the trail will be relativelyflat.
2) Every time your trail crosses the contour lines on a map you will either be ascending or descending in elevation. Going up or coming down!
3) The closer together the contour lines are, the steeper the terrain is.
Clear as mud? Good- Stick with me while I break it down!
Shared Elevation:
Contour lines are drawn along areas of shared elevation.
Note the “1,400” in the center of the map, above. The bold line moving out on either side of the “1,400” connects all areas at 1,400 ft. elevation; not 1,399 ft. and not 1,401 ft.
Quick Exercise: What is the elevation of the orange circle?
There is an unmarked bold contour line between “1,000” and “1,400.” This line is a mid-point between 1,000 ft. and 1,400 ft. You guessed it, 1,200 ft.
Now shift your attention to the thinner contour lines between 1,200 ft. and 1,400 ft. There are four contour lines that create five sections. So, each contour line shows an increase of 40ft. The math below should help clean up the idea.
1,400 – 1,200 = 200 ft.
200 ft./ 5 (sections) = 40 ft. (per contour line)
The orange circle is between the second and third contour line, above 1,200 ft. So, count up from 1,200 by 40’s. All we can say from the information provided is that the elevation at the orange circle is greater than 1,280 ft. and less than 1,320 ft. Or…
Answer: 1,280 ft. < Elevation at Orange Circle < 1,320 ft.
Figure out the elevation range of the yellow circle on your own, using the same principles above! Answer is at the end of the article.
Relatively Flat Trail
When a trail meanders parallel to, or, within two contour lines, the trail will be relatively flat.
The map above shows a fictitious trail, but it should well illustrate this principle. The starting point of this trail is the blue circle. The ending point is the star. Follow the dotted trail markings from the circle to the star. Note that the trail is entirely between the contour lines for 1,200 ft. and 1,240 ft. All we can know from what is pictured above is that the trail will be relativelyflat, never causing you to ascend above 1,240 ft. nor descend below 1,200 ft.
Trails Crossing Contour Lines
Every time your trail crosses the contour lines on a map you will either be ascending or descending in elevation. Going up or coming down!
Compare the section of trail bracketed in orange with the map of the relatively flat trail discussed above. Now our trail is crossing contour lines. This is an indicator that you will be ascending somewhat rapidly (relative to the actual hiking distance) from approximately 1,120 ft. to 1,320 ft.
Contour Line Proximity
The closer together the contour lines are, the steeper the terrain is.
Compare the proximity of the contour lines from the red area to the yellow area. The contour lines are noticeably tighter in the yellow area than the red area. This is an indicator that the slope of the terrain in the yellow area will be much steeper compared to the red area.
Trail Analysis
Let’s use one of the trails pictured above and put it all together! The following trail analysis can be completed on any trail map if you follow the principles above!
Note: The blue circle is my starting-point. The star is my ending-point. Adding the three points along the trail helps me divide up the total hike based on what the map is telling me.
A simple, know-before-you-go trail analysis sounds like the following:
“Total elevation gain is about 800 ft. From my starting-point to Point 1, I will be ascending about 300 ft. From Point 1 to Point 2 things should relatively level out. From Point 2 to Point 3, I’m going to start climbing elevation again. I definitely need to save some energy for the last push from Point 3 to my ending-point. It’s a short distance, but super steep compared to the rest of the hike. Hopefully I get a summit-like view once I get myself up there!”
That entire analysis comes from understanding the three key takeaways from this article:
1) When a trail meanders parallel to, or, within two contour lines, the trail will be relativelyflat.
2) Every time your trail crosses the contour lines on a map you will either be ascending or descending in elevation. Going up or coming down!
3) The closer together the contour lines are, the steeper the terrain is.
Hope you enjoyed this article and found it helpful!
God bless and come see us again soon!
ANSWERS TO EXERCISE:
1,800 ft. < Elevation at Yellow Circle < 1,840 ft.