"false spiders" ??
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p.titchin
This image is from an "unnamed" area, I think, towards the edge of the ice cap. At first glance, there appears to be a faint spider network forming wavy lined polygonal shapes, but I noticed the blotch and fan vents are in the centre of the plates rather than along the channels as you would expect. Plenty of room for the imagination on how these polygonal plates occur, and why they do not provide the weaknesses for vents to form along them. I'm looking for other examples, but comments and ideas would be great ~ "intrigued Pete"
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p.titchin
Deja vue, another image from the same area with venting in the centre of fractal plates. HELPsomeone, Any ideas?~pete
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Kitharode
moderator
in response to p.titchin's comment.
Sorry Pete. but I have no idea what might be going on here. I agree with your observation that the blotches tend to be in the middle of the plates, rather than the edges, but I can't imagine how this works.
Is there a clue in your title? If 'true' spiders are channels that are cut into the surface by the action of venting, then any other action, eg., freeze/thaw, shrinkage, might well create channels that look like spiders but are in fact 'false'. Perhaps an unknown action is capable of producing these polygon plates by pooling the grust (perhaps in under-ice depressions) which then oozes to the surface rather than venting through the surface, hence the pale blotches rather than dark.
Your image raises a question which has been asked on a number of occasions, in a number of ways; When is a spider not a spider? One of the best examples of the problem is in wassock's 'The Heart of The Matter' discussion. Lots of 'spiders' over the whole area, but only relatively small patches of fans which repeat over several years.
Not much help I'm afraid, but it's the best I can do. Cheers - "Intrigued and bewildered Kitharode". 😃
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mschwamb
scientist, translator
in response to p.titchin's comment.
Hiya Pete
Sorry I missed this. The theory is that the trapped carbon dioxide gas will exploit whatever weaknesses in the soil to move above under the thawing seasonal ice cap. So if there were natural grooves, the gas would likely follow those and continue to carve them deeper. Does those that help?
Cheers,
~Meg
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