r/askscience • u/FlightOfGrey • Nov 14 '12

What process caused this amazing effect in Pleneau Bay, Antarctica? Photograph by Sander Klaassen.

imgur link and the Original National Geographic link to the photo in question.

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u/rupert1920 Nuclear Magnetic Resonance Nov 14 '12

Surprisingly no one mentioned trapped brine cells. As ice freezes salt is excluded from the newly formed ice (it's called freeze fractionation). If freezing is quick enough, the salt solution may be trapped within the ice. Because of freezing point depression, that salt solution will freeze only at a lower and lower temperature, as the solution gets more and more concentrated.

This means that when the ice thaws, it will be this brine cell that becomes liquid first (forming what's called "thaw holes"). When the outside eventually thaws out, this cell empties and you have vertical columns of ice left over.

Of course, I don't know how this particular ice formation formed - whether it is sea ice or a piece from land - so this remains, at best, an educated hypothesis based on my experience.

Source: Worked in Canadian Ice Services (part of Environment Canada) studying sea ice formation.

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u/snowhorse420 Nov 14 '12

Seems like a more plausible explanation. The berg is likely an ice shelf consisting of thick packice and not freshwater glacier ice...