" spring lines"
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by
p.titchin
When I see images like this, I am struck by the way the spiders (often with blue blotches) form in a line on the lower part of the Inca ridges, just like water forms a line of springs on an earth slope. What is also weird is that if you look on the HiRISE views, you will see that lower down the line of the slope, pretty much at the base, a second "spring line" forms, of fans rather than blotches, and no associated line of spiders. I'm not sure I understand how sublimated CO2 gas does this. Something to ponder on Boxing Day! ~Pete.
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by
HMB6EQUJ5
in response to p.titchin's comment.
Nice observation Pete. I'm seeing this image on HiRISE RGB color about 1/4 down center/right. Fascinating HiRISE strip (as they all are) , so much activity in that area and yet when I scroll all the way down there are solitary fans/vents on a relatively smooth surface.
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Kitharode
moderator
in response to p.titchin's comment.
Hi Pete. Don't know how I missed this until now, but better late than never I hope.
I made mention of these lines of spiders (I called them 'fringe' spiders) in my tourist guide to Inca City and, as you say, they seem to lie along the base of the ridges. I've also seen examples elsewhere in the outlying regions of Inca City where again they lie along the base of steeply sloping objects.
It seems to me that the angle of slope plays a part in determining the spiders shape, ie., too much slope and spiders don't form, less slope and spiders are half-formed (like a fringe), minimal slope and the spiders fully form in lines. I've not got anything definitive on this yet, but it's on my to-do list because the examples I've seen so far seem to indicate that this is a definate pattern. Here's hoping ... 😉
For any passers by who are interested, here's the link to the Inca City paper - fringe spiders start on page 8. https://www.dropbox.com/sh/obn0bh8xo7pllwu/EjMj21fXky
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