Strange patterns appear on lake in Iceland

A strange phenomenon has taken over this frozen lake in Iceland, making it look like a scene taken straight from the X-Files.

Lake Thingvallavatn, Iceland's largest lake, has some local residents freaking out after a strange zig zag pattern appeared on it.

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The photos shared on the Thingvellir National Park's Facebook page show the pattern appearing on the ice sheets, which according to a park official, had never been spotted before.

But turns out this isn't actually a sign of alien activity, there's a confusing scientific explanation for all of this.

The mysterious pattern is a very rare phenomenon called 'finger rafting'.

This happens when thin ice sheets floating on water collide and push over and under each other alternately, creating what scientists describe as 'fingers'.