### Which trail would certainly you take?

Imagine. You’re out hill climbing via your friends.

You pull out your map and check out 2 hiking trails.

You are watching: Why is it unlikely that two contour lines will cross

The first route has closely-spaced contour lines.

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

Which hiking trail would YOU take?

For the slow-and-secure climber, you’d pick the second path because widely-spaced contour lines intend the slope is gradual. But if you picked the first course, you’re the kind of totally free climber that scales hills with simply a pickaxe. This is bereason when contours are cshed together, it indicates that the slope is steeper.

For a quick meaning, a contour line joins points of equal and also constant values. For example, contours on an elevation have constant heights that are the very same on each line.

### Are these contour lines mountains or depressions?

When you have a closed contour prefer the one below, this suggests tbelow is a hill/hill or depression.

You don’t really know unless tbelow is a label on the contour line. In the example below, we’ve included labels and it need to be clear that it’s a depression.

And this isn’t simply any type of depression. This is the enormous meteor crater that struck Arizona a long time earlier.

On some maps, cartographers usage teeth marks or hachures for depressions at craters or volcanoes bereason it marks the elevation goes up or dvery own.

READ MORE: A Topographic Profile of Arizona’s Massive Meteor Crater

### How does Mount Fuji’s contour lines look like?

In this situation, closed contour lines show a mountain. The beautiful Mount Fuji stands 3,776 meters tall over sea level. At 250-meter spacing, here’s how the contour lines look:

When you watch Mount Fuji in 3D, you can check out that it’s quite steep as the contours are fairly closely spaced together.

So much, we’ve seen examples of two types of closed contours, however just how perform contours look favor in valleys?

### The dominance of V and U-shaped valleys

Valleys are elongated low-lying depressions normally with a river flowing through it. You understand that you’re looking at a valley bottom as soon as contour lines are V or U-shaped.

Here is an instance of a 3D see of the picturesque Collayomi Valley in California:

All rivers flow downhill from higher to the reduced elevations, perpendicular to the contour line above it. As a dominion of thumb, the V-shaped contour is pointing upstream (the opposite direction from the circulation of a stream or river).

The “V” shape contours show streams and drainage. As you deserve to see, the “V” points uphill to a greater elevation. Generally, you deserve to attach the apexes of the upward-pointing, “V” shaped contour lines to delineate a stream. More to this, you can estimate a stream gradient by counting the variety of contours that cross a stream through the contour interval.

The slope is always perpendicular to contour lines. The less separation in between contour lines indicates a steeper slope and vice versa. When tright here are evenly spaced contours, the slope is unidevelop.

At a stream junction, contour lines create a “M” or “W” shape. This deserve to be understood as two “V-shaped contours intersecting.

### What about ridges and also gullies?

Over time, gullies form via erosion of running water on hillsides. A consequence of 2 eroded gullies is a spur at the center on the face of a hillside that sticks out. Both gullies and also spurs run from ridgelines to valley bottoms.

Gullies (or draws) are characterized by “U” or “V” shaped contour lines through their closed-finish pointing in the direction of better elevation. On the various other hand also, spur contour lines point toward reduced elevation.

In 2D, these valley landscape features are a bit more tough to view. But it’s essential to remember how ridges allude downslope and also gullies suggest upslope.

### Why carry out contour lines never before cross?

It’s unlikely that contours cross, yet periodically they carry out. When the terrain is an overhang or cliff, contour lines will certainly cross or touch.

The cliffs in Látrabjarg, Iceland are approximately 440 meters tall. When you generate 100-meter contours, they are very cshed to converging.

In 3D, you deserve to view just how steep these cliffs are. So if these contours did cross, it’s very likely an overhang. Or it can be an error in the routine.

If you usage your creativity, picture an overhang where the terrain hangs outward. This would be a rare exception once 2 contours that cross.

### How to draw contour lines manually?

You have the right to conveniently generate contour lines with the click of a switch in CAD or GIS software application. But what if you desire to attract it by hand?

First, you have to select a contour interval. For example, we’re going to use a contour interval of 10 meters. So this implies that there will be a contour eincredibly 10 meters.

Between shift points of ten (30, 40, 50, etc), add markers wbelow to attract lines. Basically, attract or interpolate between the lines.

Now that we have actually points to connect, let’s attract smooth contour lines for each interval. Basically, we are connecting the points through lines.

And tright here we have it.

### What do we usage contour lines for?

In our instance, contour lines represented consistent elevation and confirmed the topography of the landscape.

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

The closeness of contours indicates slope. Ircontinuous contours expect rugged terrain. It’s rare in nature for contours to cross. But they can for overhangs and also cliffs.

See more: Solved:Explain Why Do Metals Tend To Form Cations ? Why Do Most Metals Tend To Form Cations

What are some other forms of contours you’ve viewed in nature?

### References

Topographic Maps: The Basics, Natural Resources Canada, 2020. Recreated through the permission of the Department of Natural Reresources, 2020.