In general, nature doesn’t deal in repeated patterns of straight lines. Nature likes jagged fractals, spirals, and spheres. Elongated, straight lines are rare.

So when scientists first set eyes upon the sort of zig-zag patterns that have now appeared in Iceland’s Lake Thingvallavatn, they really didn’t know quite what to think. They’ve been spotted in different ice formations from around the world, but this particularly pattern stretches for 2 kilometers (1.2 miles), according to the officials working in Thingvellir National Park.

“Today someone noted a strange looking pattern in the ice cover which is still unexplained and locals have not seen before,” they wrote on the park’s Facebook page. “For the last 15 years solid ice cover on the lake has not formed as solid as in the past due to increasing temperatures. The lake has gathered partial ice cover for shorter periods and more unstable.”

The question is, if the ice cover is thin and unstable, why isn’t it cracking somewhat more randomly? Why does it look so organized in this case? Are these the cryo-versions of crop circles or something?

Actually, this is probably an example of something called “finger rafting,” a phenomenon that’s been documented fairly heavily in the sea ice of the Arctic and Antarctic regions.

When two thin segments of ice drift towards each other, one tends to slide atop the other. This doesn’t happen all that smoothly, though – some of the ice slides over the other sheet, whereas other parts descend beneath it.

Peculiarly, this finger rafting process tends to form fairly symmetrical, repetitive patterns of ice sliding above and below. It’s named after the interlocking pattern of human fingers, quite understandably. These rafts have only just started appearing in Iceland because the lake ice there nowadays is unprecedentedly thin, which means it can drift around with reckless abandon.

So yeah – it’s not aliens. Again. Goddamn it, science.

Here’s a bit of bonus etymology for you, though, to make up for a distinct lack of extraterrestrials. The undersliding submerged ice bits are named “bummocks”, which are literally the bottom version of icy hummocks, which are humps that protrude upwards. Now there’s some curious scientific terminology for you.

[H/T: ScienceAlert]