Planet Four Talk

What geologic forces

  • bobwiersma1322 by bobwiersma1322

    The ridges could be dunes. the dark fans could be new or old sediments. any examples of this on earth?

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  • p.titchin by p.titchin in response to bobwiersma1322's comment.

    hi, those' ridges' are in fact channels (optical illusion caused because the light is from the bottom of the image, whereas our brains like it lit from above) blasted out of the surface under the ice sheet by subliming CO2. The gas can vent to the surface carrying surface material, which forms the fan like dark deposits. Welcome to the club, and hope like many of us you find these images fascinating. Watch out though- P4 can be highly addictive! ~ Pete

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  • JellyMonster by JellyMonster

    Pete is right. I first copied the image then rotated it through 180 degrees. I also altered the contrast - can you see the channels now?

    enter image description here

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  • EA2014 by EA2014

    Thanks, JellyMonster! It made a huge difference in this particular image (& it's a fascinating one).
    Another question about geologic forces ... I'm a 'newbe' to P4 & already 'addicted', as Pete commented ... I'm trying to find my way around the science articles & blogs. What's the relationship (if any) between 'spiders' and 'polygonal landscapes'? .... any idea of what actually 'starts' a spider development? .....(oops - I see that was TWO questions) ~Elizabeth

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  • Kitharode by Kitharode moderator

    Hi Elizabeth. Welcome to the 'P4 Addicts Club'. 😃 You've raised two very good and rather slippery questions there. You'll probably get more than one answer to each of them. Let's hope so, because mine will probably be wildly wrong.

    Taking your 'how do spiders start' question first: I'm not sure that there's a definate answer to that. The general theory says that the venting of dust carves (and extends?) the spider channels, but it's not clear (to me at least) whether this venting activity can actually start a new spider. The age of spiders is not well known and there is no firm evidence (yet) that the channels are growing. My gut-feelings tell me that 'landscape makes spiders', leading to 'spiders make venting'.

    I've a feeling that 'polygonal landscapes' come in two flavours. One is polygon cracking of the icelayer which gives rise to those 'linear venting' images we see, but they do not seem to form linear spiders in the same polygon pattern as we see in the ice. Eg. http://planetfour.org/subjects/standard/50e73eb35e2ed21240001d4a.jpg

    The other type of polygons are definately surface features, probably responsible for much of the 'lace terrain'. Eg. http://planetfour.org/subjects/standard/50e7410c5e2ed212400030d4.jpg (We sometimes use the nickname 'Grust' for the gassy-icey-reddish-dusty stuff we see occasionally). 😃

    Between us we have quite a few articles, abstracts, and such like, so if you fancy some heavy reading on a particulat area do please ask. The science team can often point you in the right direction, if you ask nicely. 😉 Cheers.

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  • wassock by wassock moderator

    Elizabeth, have a look at this thread http://talk.planetfour.org/#/boards/BPF0000009/discussions/DPF0000ccj the main image shows a big strip of Mars with lace terrain in the middle which..... well you' ll see.

    Wrt spider formation as Kith has said we don't have any images which show changes to any spiders year on year. In fact most of Mars seems to be fairly static. So the idea is that they form very slowly. Because the spiders exist where the fans are formed the theory has developed that one forms the other. However there are areas with no spiders where fans are formed and areas with spiders that do not form fans. So for my money the "fans cause the spiders" causality is not proven, but is the best model we have at the moment.

    Hope you have fun here and don't be afraid to question - no-one has a handle on exactly what is going on here or can explain everything we're seeing.

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  • michaelaye by michaelaye scientist

    Hi guys!
    Welcome EA2014, we are glad for every helping clicking finger, I'm glad you find these images as fascinating as we do.
    I'm impressed by the quality of explanations you already have received, well done, hard-working moderators! (By the way, Kitharode, you have pressed the submit button more than 30,000 times so far, if I remember correctly from my latest stats doing.)

    One comment to developing spider forms: We might have discovered some changes, but don't want to share that yet, because that would be quite some discovery. So it would be good to at least keep your mind open, just in case you mega-clickers remember a certain pretty spider looking differently in some other image. If you guys notice any changes that would be awesome as well.
    Keep the main focus on the fans and blotches though, we are pretty sure that at some point we will launch a special spider hunting or marking zooniverse project, but that shall come after we have produced some science results with all your hard work (which we recently produced a draft layout for).
    As always, thanks for your work!

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  • EA2014 by EA2014

    Having worked for a long time in Geographic Information Systems, I appreciate the fact that LOTS of good data is very hard to come by - and very valuable. The best analysis in the universe is useless if the data is poor. So to that end, I'm delighted to keep 'clicking' away on Fans & Blotches, while making a note of other features.

    I'm very appreciative of the informative and gracious feedback by the Moderators and Scientists. It's wonderfully unexpected (by me) and provides tremendous impetus for classifying 'just one more image'! After all, the reason many of us are volunteering is that we're also driven to 'explore & find out more' and see the value of this project.

    As an aside ... if there are any articles/papers available on "spider development ideas" that would not jeopardize any particular research, findings or persons ... it would be appreciated. Otherwise - not a problem. I have plenty to keep me interested and busy! ....... Many thanks to all!
    ~Elizabeth

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  • EA2014 by EA2014

    By the way Kitharode and wassock .... the reference images you suggested were terrific and the 'strip image' blew my mind! 😃 😃 😃
    ~Elizabeth

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  • Kitharode by Kitharode moderator in response to EA2014's comment.

    That 'strip image' of wassock's is indeed a mind-blower. There's probably a lifetimes work in that image alone.

    I think you're right about the 'explore & find out more' thingy. I've known the general stuff about Mars for years, but honestly, I've learnt more about the planet in this last twelve months than I have in the last twelve years. The southern polar regions are almost like a second home now. 😃

    Re science articles: I've got a couple of items off the internet that might be useful. If you want to give me an email address by personal message I'll send them to you. Cheers.

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