Sciency Words: Chaos Terrain

Sciency Words PHYS copy

Sciency Words is a special series here on Planet Pailly celebrating the rich and colorful world of science and science-related terminology. Today, we’re looking at the term:


Chaos terrain is a weird concept, so I’ve decided to let a master of chaos terrain formation explain.

Ag09 Europa Intro

First, you’ll need an ocean of liquid water with a layer of water ice on top. For best results, I recommend using pure or nearly pure ice and really salty ocean water, so that they’ll have dramatically different melting/freezing points.

Ag09 Chaos Terrain Diagram 1

Next, set up some volcanoes or hydrothermal vents on your ocean floor. A little volcanic activity will cause the sporadic melting and refreezing of your ice, allowing ice water and saltwater to mix. If you do this right, you’ll end up with a salty “lake” trapped between layers of ice.

Ag09 Chaos Terrain Diagram 2

As we all know, liquid water is denser than water ice, so your lake will cause the ice above to sag and eventually cave in.

Ag09 Chaos Terrain Diagram 3

Cracks and fissures will form. Chuncks of ice will break apart, and that salty liquid water will get the chance to seep into the gaps, causing more melting and refreezing mayhem.

Finally, when your lake refreezes, it will expand (remember: ice is less dense than water) pushing all that cracked and broken material upward.

Ag09 Chaos Terrain Diagram 4

The resulting terrain will look truly bizarre—chaotic, you might say!—with huge ice blocks jutting up above an otherwise perfectly smooth landscape.

Ag09 Europa Final Thoughts

So, fellow planets and moons, what else can we do to confuse the humans? Share your ideas in the comments below!


Active Formation of “Chaos Terrain” over Shallow Subsurface Water on Europa from Nature (beware of paywall).

Europa’s Chaos Terrains from NASA Visualization Explorer.

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