I was hiking a very popular trail in Akamina-Kishnena Provincial Park, and noticed these strange lines in the rocks on top of the mountain:

enter image description here

The lines were parallel to each other, and were on both sides of the trail covering quite a large area of the mountain face. My best guess is that run off from snow melt could cause this, but they look almost like they were raked. The picture was take at around 2,400m in elevation. What causes this?

This is the ridge we were on:

enter image description here

The lines were on the southern face of the mountain.

  • $\begingroup$ I would guess hydrology $\endgroup$ – Paparazzi Aug 5 '17 at 6:33
  • $\begingroup$ @Paparazzi, That's my guess too, but the area was so large and the rows were so evenly spaced and straight. It didn't look natural, but considering where we were it has to be. $\endgroup$ – ShemSeger Aug 5 '17 at 6:36
  • $\begingroup$ Water on an even surface can produce very regular patterns. There is a limestone wall (not steep) where you have evenly spaces water creases over a long distance. Obviously that's another situation than you encounter, it's just an example of weirdly regular but natural patterns. $\endgroup$ – imsodin Aug 5 '17 at 10:00
  • $\begingroup$ @Pont I'd be fine with that if someone is able to migrate it. $\endgroup$ – ShemSeger Aug 8 '17 at 20:56
  • 1
    $\begingroup$ en.wikipedia.org/wiki/Patterned_ground#Stripes $\endgroup$ – ShemSeger Aug 11 '17 at 14:24

Frost heaving of the striped variety

As soil freezes it expands, this slowly pushes coarser material outwards, (since no ice forms in the stones just between them). This forms in bands of coarse and fine material like you see in your image.

The effect only becomes more exaggerated as the soil gets more and more sorted, since the finer material holds more water and thus expands more. This also means that even the smallest variation in particle size can get the process started.

A variety of patterns can form; sloped ground is especially prone to this sort of striped frost sorting.

B and C in this image are examples from this paper. enter image description here

Additional source


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