Dark areas on surface, what are they?

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PostPosted: June 3, 2014 1:21 PM 

I'm very sorry for the double topic, I don't know how to edit the previous one or how to delete it. Sad Can any moderators out there delete the oldest?

Hope the image shows up now.


I've been looking at some mars photos and found these dark areas in some places. This is a particularly dark one. What is this, do you have any idea?


Posts: xxx

Reply: 1

PostPosted: June 4, 2014 6:28 AM 

Dust Devils create these darker streaks but as we have been discussing sand slides are occurring too. Material just beneath the surface tends to be darker we have seen from the drilling events sub-surface material is a sort of blue grey colour.


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PostPosted: June 4, 2014 6:55 AM 

But it seems odd that these seem to appear on areas with no apparent sand slides. As for dust devils, I didn't know they could create such dark streaks thanks for the info. I mean, what made this image stand out for me is that the streak is particularly dark and with very well defined borders, and also with no other streaks nearby.


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PostPosted: June 4, 2014 10:44 AM 

Some examples here:



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PostPosted: June 4, 2014 11:11 AM 

Nice images! But the image I showed doesn't seem to be a dust devil. Probably a sand slide, because they all come from higher terrain. Sand seems to be pouring out in some places.

Hope these links work...



Joe Smith

Posts: 86

Reply: 5

PostPosted: June 4, 2014 12:59 PM 

Welcome to Mars Rover Blog Filipe;

Filipe,, I still can't open your flicker link
please try again? Or perhaps I might search flicker for /92172119@N02/14158598029,, I just this moment thought of that. Thanks.
Don't be a stranger. Welcome aboard.


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PostPosted: June 4, 2014 1:14 PM 

Hi Joe, thank you

If you just copy and paste this to your address bar it will work.
Is there a way to post images or links directly in the post?



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Reply: 7

PostPosted: June 4, 2014 3:49 PM 

Use the HTML 'A' tag. Just embed it in your text post.



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PostPosted: June 4, 2014 3:51 PM 

Then you will see something like this:

HTML A tag


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PostPosted: June 4, 2014 4:32 PM 

Like this?

Image 1!
Image 2!
Image 3!


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PostPosted: June 4, 2014 6:07 PM 

Hi Filipe,

To My eyes they are all slope streaks. Caused by maybe water maybe dust slide maybe melted ice. If you look close at the first image you posted #1, you will see old faint slope streaks below the very dark on.


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PostPosted: June 4, 2014 10:42 PM 

Hi Filipe;

Welcome aboard!
I agree with looking@Mars that they all look like slope streaks. I suspect that the cause is debris gravity flows incorporating small amounts of water from the subsurface that sublimes on meeting the martian atmosphere.

There is a lot of discussion on Debris flows and TSL's in two other current discussions on this Board.

I don't think they are dust devils as they lack the typical conformation and characteristic random orientation of dust devils.



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PostPosted: June 5, 2014 5:16 AM 

Images 2 and 3 are slope streaks but image 1 only seems to have a partial slope to the left so not sure if I agree that is a slope streak also it seems to be very dark and very sharp where is slope streaks tend to have more fading and streaks within streaks. If that makes sense.


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PostPosted: June 5, 2014 5:59 AM 

Thank you! I feel welcome!

Yes probably underneath layer of soil pouring out in some specific places. But some of them are so well defined. I'm still not completly sure about this. Will continue to search on photos.

What an idiot I am! Posted the same image twice on my last post...

Here are the 3 correct images now...
Isn't there a way to edit posts?

Image 1

Image 2

Image 3

Is this the right section to be posting? I'm a bit confused with this forum...

Kye Goodwin

Posts: 1166

Reply: 14

PostPosted: June 6, 2014 10:39 AM 

Filipe, Yes, Welcome. Those are all slope streaks, alright. Mars Science is intrigued by the slope streaks, but so far the streaks have kept their secrets well. No one knows what they are even to a first approximation. Gravity is involved, almost certainly, but there is no agreement on what substance is moving downslope or even that downslope movement of material is primarily what's going on. It could be that a state change of some kind is what spreads downslope, rather than any significant amount of material.

Its a deep mystery, but there's a lot of online information available. Google "slope streaks Mars". Lately these have also been called "recurring slope lineae".

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