Which trail would certainly you take?

Imagine. She out mountain climbing with your friends.

You pull out your map and see two hiking trails.

You are watching: How does a topographic map indicate the direction that a stream flows?

The first route has actually closely-spaced edge lines.

But the second route has actually widely-spaced spaced contour lines.

Which hiking trail would certainly YOU take?

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For the slow-and-steady climber, you’d choose the 2nd route because widely-spaced edge lines mean the slope is gradual. However if you picked the first route, you’re the form of complimentary climber that scales mountains with just a pickaxe. This is since when contours space close together, it means that the steep is steeper.

For a rapid definition, a contour line joins points of equal and consistent values. Because that example, contours on an key have constant heights that space the exact same on each line.

Are this contour lines mountains or depressions?

When you have actually a closeup of the door contour prefer the one below, this means there is a hill/mountain or depression.

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You don’t really know unless over there is a brand on the contour line. In the example below, we’ve added labels and it must be clear the it’s a depression.

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And this isn’t just any type of depression. This is the enormous meteor crater that struck Arizona a lengthy time ago.

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On some maps, cartographers use teeth point out or hachures because that depressions at craters or volcanoes since it marks the elevation goes up or down.

READ MORE: A Topographic profile of Arizona’s huge Meteor Crater


How does mount Fuji’s contour lines look at like?

In this case, closed contour lines indicate a mountain. The beautiful mount Fuji was standing 3,776 meter tall above sea level. At 250-meter spacing, here’s just how the edge lines look:

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When you watch Mount Fuji in 3D, you deserve to see that it’s rather steep together the contours are reasonably closely spaced together.

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So far, we’ve seen examples of two types of close up door contours, but how perform contours look prefer in valleys?


The dominion of V and U-shaped valleys

Valleys room elongated low-lying depressions usually through a flow flowing through it. You recognize that she looking in ~ a valley bottom once contour lines are V or U-shaped.

Here is an example of a 3D view of the picturesque Collayomi sink in California:

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All rivers circulation downhill from greater to the lower elevations, perpendicular to the contour line over it. Together a ascendancy of thumb, the V-shaped edge is pointing upstream (the opposite direction from the circulation of a currently or river).

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The “V” shape contours suggest streams and drainage. Together you can see, the “V” points uphill to a higher elevation. Generally, girlfriend can connect the apexes of the upward-pointing, “V” shaped contour lines come delineate a stream. More to this, you have the right to estimate a stream gradient by counting the number of contours the cross a stream through the edge interval.

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The steep is constantly perpendicular to contour lines. The less separation between contour lines means a steeper slope and also vice versa. As soon as there room evenly spaced contours, the slope is uniform.

At a present junction, edge lines form a “M” or “W” shape. This deserve to be understood as 2 “V-shaped contours intersecting.


What about ridges and also gullies?

Over time, gullies kind through erosion of to run water ~ above hillsides. A consequence of two eroded gullies is a spur at the facility on the challenge of a hillside the sticks out. Both gullies and spurs run from ridgelines to valley bottoms.

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Gullies (or draws) are identified by “U” or “V” shaped contour lines with their closed-end pointing towards higher elevation. On the other hand, spur contour lines allude toward lower elevation.

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In 2D, these valley landscape features are a little bit more difficult to see. Yet it’s vital to remember how ridges point downslope and gullies point upslope.

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Why carry out contour lines never ever cross?

It’s unlikely the contours cross, yet sometimes they do. Once the terrain is an overhang or cliff, edge lines will certainly cross or touch.

The cliffs in Látrabjarg, Iceland room up come 440 meter tall. As soon as you generate 100-meter contours, they space very close to converging.

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In 3D, you can see exactly how steep this cliffs are. For this reason if these contours walk cross, it’s really likely an overhang. Or it can be one error in the program.

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If you usage your imagination, picture an overhang where the terrain hangs outward. This would be a rare exemption when 2 contours that cross.


How to attract contour currently manually?

You can easily generate contour lines with the click the a switch in CAD or GIS software. But what if you desire to attract it by hand?

First, you have actually to pick a contour interval. Because that example, we’re walk to usage a contour interval that 10 meters. Therefore this means that there will be a edge every 10 meters.

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Between transition points that ten (30, 40, 50, etc), add markers whereby to draw lines. Basically, draw or interpolate between the lines.

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Now the we have points to connect, let’s draw smooth contour lines because that each interval. Essentially, we room connecting the points through lines.

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And over there we have it.


What carry out we use contour lines for?

In our example, contour lines represented consistent elevation and showed the topography that the landscape.

But meteorology (isopleth), magnetism (isogon) and even drive-time (isochrones) likewise use contours for different purposes.

The closeness of contours indicates slope. Irregular contours median rugged terrain. It’s rarely in nature for contours to cross. Yet they can for overhangs and also cliffs.

See more: A Root Springs From The Ground Runescape, Weird Roots Spring From The Ground

What room some other species of border you’ve checked out in nature?


References

Topographic Maps: The Basics, organic Resources Canada, 2020. Reproduced through the permission that the department of herbal Resources, 2020.