'Linear Pits' in Candor Chasma Wallrock (MRO)

[paulanderson]

An interesting feature in the new MRO image of Candor Chasma Wallrock (TRA_000862_1710), October 5, 2006 (first noted in the Unmanned Spaceflight.com forum). Long straight line of small "pits" stretching diagonally across the slope. I've posted two cropped images from the original largest 47MB image (the wider view image, not the sub-image). The first one of the entire feature, the second a closer zoom of the left portion:<br /><br />http://www3.telus.net/paulanderson/linearpits1_TRA0008621710.jpg<br /><br />http://www3.telus.net/paulanderson/linearpits2_TRA0008621710.jpg<br /><br />A lot of the pits seem to be roughly in pairs. Crater chain? Volcanic vents? Other? Must be very small as they are near limits of resolution (26 cm/pixel with objects ~78 cm resolved).<br /><br />Original images:<br /><br />http://hiroc.lpl.arizona.edu/images/TRA/TRA_000862_1710<br /><br />Alternatively, you can also zoom in to see the feature:<br /><br />http://marsoweb.nas.nasa.gov/HiRISE/hirise_images/mapped/TRA_000862_1710<br /><br />Near top centre of image, just left of central "ridge" below the black border.<br />

 

[bonzelite]

this scarring appears as well on Phobos. and i do not believe for a minute they are impact craters.

 

[thebigcat]

Looks to me like something went bouncing down the hill. Notice that there are several other linear and curvelinear features with approximate the same directional alignment in the area. <br /><br />What is the slope there? Do they even know? <div class="Discussion_UserSignature"> </div>

 

[ittiz]

Yeah if you look at the whole image there is a ridge there. I have a feeling that a rock just rolled down the hill. With the low Martian gravity it could bounce for quite a ways before coming to rest.

 

[green_meklar]

Like they said, a rolling rock would probably explain it best. I wouldn't get all worried about alien invasions if I were you. <div class="Discussion_UserSignature"> <p>________________</p><p>Repent! Repent! The technological singularity is coming!</p> </div>

 

[MeteorWayne]

Looks like rock and roll to me <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[billslugg]

Back in July '92 I travelled to the Mojave to see the surface fault (and 11 foot offset) created by the 7.3 Landers quake of 6/28. At one point I was standing at the base of a mountain, looking out across the desert floor. I saw a crater about 50 feet away and about 10 feet wide by 3 feet deep. I thought "What in the world could have caused that?" Then I saw another crater about 50 feet farther out in the desert, and then another one and then a BIG rock. I swung around and looked up at the mountain and saw a series of bright markings extending all the way up to a ridge.<br />Whoa! I'm getting out of here!<br /> <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[bonzelite]

<br />bounce marks: <br /><br />that's a clever idea, but i would not put money on that. the spacing of the craters in the chain, and the shape of the footprints don't convince me of a traveling bouncing boulder. <br /><br />as well, where is the boulder? and the markings on Phobos are nearly the same. i doubt a boulder skipped across Phobos multiple times from edge to edge, in multiple chains, making nearly perfectly linear forms. <br /><br />granted, i have no idea what made them. i would be more likely to buy etching scarring. how and why --don't know. <br /><br />

 

[green_meklar]

<blockquote><font class="small">In reply to:</font><hr /><p>as well, where is the boulder?<p><hr /></p></p></blockquote><br />Who knows? Maybe under the sand. Or maybe one of the last marks in the row <i>is</i> the boulder.<br /><blockquote><font class="small">In reply to:</font><hr /><p>the markings on Phobos are nearly the same.<p><hr /></p></p></blockquote><br />Can I see a picture of them?<br /><blockquote><font class="small">In reply to:</font><hr /><p>granted, i have no idea what made them. i would be more likely to buy etching scarring. how and why --don't know.<p><hr /></p></p></blockquote><br />What about the idea of a meteor falling into pieces as it approached the ground? Normally you wouldn't think that would make a straight line, but it might be possible. <div class="Discussion_UserSignature"> <p>________________</p><p>Repent! Repent! The technological singularity is coming!</p> </div>

 

[paulanderson]

I'm doubting a rolling or bouncing boulder, since the "line" is seemingly going diagonally across the slope, not straight down the slope. I first thought meteor chain, although I'm curious as to why many of the pits are grouped as they are, in pairs.<br /><br />These linear collapse features in Elysium are interesting, for comparison (although larger, and 19 metres resolution in the image):<br /><br />http://themis.asu.edu/zoom-20061009a

 

[green_meklar]

<blockquote><font class="small">In reply to:</font><hr /><p>These linear collapse features in Elysium are interesting, for comparison (although larger, and 19 metres resolution in the image): <br /><br /><hr /></p></blockquote>>http://themis.asu.edu/zoom-20061009a<p><hr /><br />You're right, they aren't straight but they do look rather strange.</p> <div class="Discussion_UserSignature"> <p>________________</p><p>Repent! Repent! The technological singularity is coming!</p> </div>

 

[vandivx]

<blockquote><font class="small">In reply to:</font><hr /><p>These linear collapse features in Elysium are interesting<br /><hr /></p></blockquote>>http://themis.asu.edu/zoom-20061009a<p><hr /><br />those I would hazard to guess look very much like crevices on a glacier, some ground shifting opened up cracks and they got blown over and closed by dust and regolith I would suppose which subsequently fell down in places exposing the crevices (or else the cracks managed to be bridged only in those places where they are bridged and in due course all cracks may get covered), same as snow covers cracks that open up in a glacier<br /><br />but take that view as you would from amateur guessing because that's what it is<br /><br />those double pits or 'Linear Pits' are weird, one idea that came to me how to explain the doubling feature is that the surface got hit by a surface glancing meteorite that hit at extremely shallow angle grazing the surface which has ridges in it and it pierced those ridges and made couple marks in each ridge as it went, one mark (hole) it made while entering the ridge and another when exiting, that would explain the puzzle of 'doubling'<br /><br />http://marsoweb.nas.nasa.gov/HiRISE/hirise_images/mapped/TRA_000862_1710/<br /><br />only it seems that in the upper left where presumably the tracks started there is a misalignment in the first several Pits (like six of them or three 'couples') ... (if my guess is right that the general slope is in the direction down and to right as looking at the region on monitor and if I reasonably assume the phenomenon started at top and continued in the direction of accross the general down slope under an angle also sloping down)<br />simple explanation would be that a smaller piece have broken off the meteorite before striking the surface and it hit the surfa</p> <div class="Discussion_UserSignature"> </div>

 

[billslugg]

There is another good example of linear pits in the same image. If you can find the original set, (It is at the top left corner of the middle photo (of the three stitched together)) here, zoom in fully, click 31 times to the right and ten times up. <br /><br />In both cases, it appears that the "boulder that ran down the hill" is going diagonally to the down slope.<br /><br />In case #1 the pits are in groups of three, not two. In case #2, they are in pairs.<br /><br />Can anyone confirm that downslope is toward the top of the photo? I assume that because it looks to me that there are mountains at the bottom of the photo. Also look at the flow patterns, as the material flows around obstructions. <br /><br />In the second case, the boulder would have come to rest off screen (at the top of the photo).<br /><br />Here is the problem. If the top of the photo is lower elevation, and the boulders were rolling toward the top of the screen, then how can we explain the offset in case #1 near the upper left of the row of pits? It looks very much as if the boulder was rolling from upper left towards lower right, hit a boulder plainly seen in the photo, shifted it's course to its left, and continued. If so, either the boulder ran up hill, or lower elevation is toward the bottom of the photo (and the mountains are not really mountains) or the rolling boulder theory is false. <br /><br />Also, can anyone explain why there are so many heart shaped craters? I came out with this impression after panning the entire image at the highest magnification.<br /><br />I would post an image of a few heart shaped craters, but I can't figure out how to copy this image. When I right click on it I get a dropdown with no copy option. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[vandivx]

it says "downslope is towards the top of the sub-image" and that sub-image below zoomable photo is oriented the same way as the main image, so you would seem to be right<br /><br />"downslope is towards the top of the sub-image" would mean that the terrain slopes downwards to the top of the photo, ie. top of the screen view is at lower elevation, if I understand that description, however I originally thought that the slope is the other way judging by the side gullies in the main rock ridges (at the bottom of the photo)<br /><br />if the bottom of the slope is really at the top of photo, then those side gullies run wrong way, at least that's how it looks to me, it might be that what I think are ridges are actually main gullies, images sometimes have way of inverting in your view, the other day in that thread on Mars pictures with Victoria crater that has those dunes at the bottom of it, sometimes on first view (say when I return to view the picture again next day) I would see those dunes inverted and looking as a sort of plush pillows rises and only after a bit of looking at them they invert in front of my eyes and I see them properly as dunes with sharp ridges sticking up.... makes me wonder if that happens to others viewing that picture too if you get what I am talking about <br />it makes me wonder if I see those mountain rock ridges as they are supposed to be seen or if my eyes play tricks on me here also<br /><br />I would interpret the photo as sloping down towards the bottom of the screen view with the upper two thirds being rubble run off which is less steep than the bottom bend of rocky ridges, you get such aprons covered with gravel in mountains on sloping ledges that end with steeper drop off where rocks are exposed and the side gullies running off those rocky ridges are always pointing downslope, naturally enough, that's why I thought that the slope is downwards on our screens as we see it<br /><br />in any way, those streaks of marks run wrong way across the slop <div class="Discussion_UserSignature"> </div>

 

[extrasense]

This much stright line with regular spacing, is the most unlikely to be of natural causes!<br /><br />It must be remains of a wall, build by martians or aliens.<br /><br />ES<br />

 

[telfrow]

If you'd like to discuss the feature from that particular point of view, please open a thread in Phenomena. <br /><br />Your post is off topic in this thread.<br /><br />Thanks. <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>