APOD: Slope Streaks in Acheron Fossae on Mars (2010 Mar 01)

[APOD Robot]

Slope Streaks in Acheron Fossae on Mars

Explanation: What creates these picturesque dark streaks on Mars? No one knows for sure. A leading hypothesis is that streaks like these are caused by fine grained sand sliding down the banks of troughs and craters. Pictured above, dark sand appears to have flowed hundreds of meters down the slopes of Acheron Fossae. The sand appears to flow like a liquid around boulders, and, for some reason, lightens significantly over time. This sand flow process is one of several which can rapidly change the surface of Mars, with other processes including dust devils, dust storms, and the freezing and melting of areas of ice. The above image was taken by the HiRise camera on board the Mars Reconnaissance Orbiter which has been orbiting Mars since 2006. Acheron Fossae is a 700 kilometer long trough in the Diacria quadrangle of Mars.

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[lakeside]

It is clear to this former geologist that sliding dark colored sand is not the explanation of the streaks. The margins of the streaks show that there has been NO disturbance of the surface whatever. Surface features continue across the streaks uninterrupted by any movement of the material. These streaks are most likely to be liquid of some sort traveling underground and wicking up through fractures into overlying sediments. This is also confirmed by the fact that the liquid concentrates in the streaks at the bottom of the slope judging from the darker staining there. Reduced staining of lumps and bumps also firs the capillary action theory. Keep in mind that sliding sand would form small delta like effects and a scalloped edge at the bottom of the slope and no such thing is present. I have watched sliding sand on the drying leeward side of sand dunes and this is different. Bleaching of the streaks is perhaps most interesting, and suggests to me that the staining may be caused by life forms.

[Oldfart]

It seems improbable that dark sand could somehow spread out from point sources in the way shown. This stuff looks exactly like crude oil, emerging from little springs. Wow!

OF

[The Code]

It seems improbable that dark sand could somehow spread out from point sources in the way shown. This stuff looks exactly like crude oil, emerging from little springs. Wow!

OF

And now I expect there,s a couple of ships going that way early next week. There,s gold in them there hills .
Any chance of a lift

Mark

PS
Looks more like volcanic ash to me.

[blastoff]

my guess is graphite dikes.

[thongar]

Guys:

1. The Red/white dust is flowing over the Black base material. Look between the two big streaks in the center of the picture, you will see one dark area covered with a thin venier of dust showing the black underneath as a grayish tint. Look up avalanche theory.

2. If anyone has built sand castles, (yes I still do whenever I get the chance) they would see almost the same process and the sand dries and the finer paticales beak free and flow. This is especially visible when sandbar sand is used. As an experiment if you have a large rock and wet sand, as the sand dries this very same formation will appear on a micro scale. Look up fractile sand flows.

3. In this picture we may be seeing the result of Marsquakes. Something like that would shake the loose sand free. Proof of quakes would certainly be something new. Eh? (Canadian for "ya know?")

Enjoy.

Sometimes to see the obvious a two by four is needed

[orin stepanek]

Because of what appears to be darker material; I wish we could pan over toward the lower left corner of the picture. There seems to be a flat area there; and it seems to be quite a bit darker.

[biddie67]

I vote for pelletized oil - if it were, I'd bet that Obama would change his dictum to NASA about the manned space program ....

The suggestion above about "Marsquakes" is fascinating - how much mass does an object need with what kind of internal structures and stresses to create the conditions for quakes?

[thongar]

Biddie67:

The Marsquake would be the cause of the dust slide . The slide evidence of the quake. It needn't be a very large quake; a Local meteor strike would cause it if the dust was light enough and the slope was steep enough. A 3-D picture might give some idea of the slope, the mass of the dust is another thing. The map of Acheron Fossae seens to indicate geological faulting, faulting in my neck of the woods means earthquakes, so why not Marsquakes on the Fossae?

As for the oil pellets... the movie ALIEN gives an indication of the dangers of spacial transport of petroleum products.

Orin:
Click on one of the hot buttons it goes to an overall photo, you can see some fans at the base of the slope. They are orange/Gray, not black (B/W Photo).

Enjoy.

[Redbone]

I don't buy the red/white dust overflowing the black base material for the simple reason that this ignores the very unusual presence of a black base material. It (the black base material) would long ago have been covered if it were not being replenished. Some process is creating a very black base material, which is then being exposed and/or covered by the 'normal' red/white sand.

[bystander]

The map of Acheron Fossae seens to indicate geological faulting, faulting in my neck of the woods means earthquakes, so why not Marsquakes on the Fossae?

That would imply that Mars is geologically active. I don't think that is the case. Although nearby impacts could cause some sliding, I think most slides on Mars should be compared to sand dune slides and snow avalanches.

Orin: Click on one of the hot buttons it goes to an overall photo, you can see some fans at the base of the slope. They are orange/Gray, not black (B/W Photo).

As for color, although the RGB pictures probably give a good approximation of the colors on Mars, I don't think any of the pictures should be considered true color. Orin's reference to darker material is quite appropriate. Even the HiRISE caption speaks of dark and light-toned streaks and not orange/Gray.

[DonAVP]

I am not sure if this has been mentioned before or that most here know this.

If you click on the ADOP image the picture only will be displayed. When you move you mouse cursor over the image you will see it change into a '+' icon. A right mouse click will download the full-size file of the image. This specific image is quite large (almost twice as big). You will be able to see a lot more detail. Check it out if you haven't.

Don

[sailorbilly2010]

I like Lakeside's explanation, "streaks are most likely to be liquid of some sort traveling underground and wicking up through fractures". However, I would suggest the fading effect is from some evaporative, drying process as opposed to a life form.

[markemark33]

Well I have to say the surface is intact and there is no sign of sliding or other surface disturbance. The wick action theory is interesting too however the uniformity of coverage is a major issue. I think that it is a life form that is using the ice to live. This is perhaps like a microbe or perhaps fungus or lichen. Notice that there are gray streaks near the black? I think this is dead life forms.

[rockwiler]

Looking at the top center-right part of the picture it is evident that the corrugated texture of the landscape relates directly the process of streak formation. Hummocky, corrugated streaks having similar geometries to the gray streaks are visible in the orange-tan area.

Also, elsewhere, it is noteworthy that the terminations of streaks to the lower left tend to be slightly more blunt than the terminations to the upper right. Furthermore, in the parent image linked below these streaks terminate onto an older surface with generally quite stubby terminations. Streaks are also normal to a sinuous ridge line (based on shadowing direction) which indicates it is related to topography not faulting.

Also, faulting as an explanation is unlikely as no modifications are visible in the older terrain on the left in the linked image below.

http://hirise-pds.lpl.arizona.edu/PDS/E ... browse.jpg

Together these factors suggest some form of mass wasting with a general right to left direction of transport. While it would be helpful to have a sense of the scale, and also topographic data to help constrain such things these are not really necessary. This process is probably something like a low gravity equivalent to rock field formation in mountainous settings on Earth. For comparison look at these coordinates in Google Earth, which is an area in Nevada underlain by Tertiary basaltic volcanic rocks. The general landform is similar. The dark streaks are rock fields consisting of approximately fist-sized angular fragments of basalt. Between the streaks the ground is vegetated, a factor that no doubt contributes to some dissimilarities with those in the Mars image. Also, this area is modified by dendritic drainages, another variant not present on Mars. Nonetheless the similarities are striking.

longitude -119.0948237006043
latitude 39.80667456232467

I think wicking of fluids up through the medium can be discounted as this would almost invariably produce a colliform or dendritic pattern rather than what we see. Also, it appeals to more processes than necessary, especially undocumented ones, which strains Ockham's Razor.

This is a low-gravity, lifeless-planet, zero-rainfall version of rock train formation, with older trains covered to increasing extents by transported dust. The rock material involved is dark in color, and is likely of a particle size orders of magnitude larger than the dust particles, as there is no apparent mixing of the two in the new dark rock trains. As soon as a new rock train forms the miniscule amount of dust covering the rocks is lost into the rock pile, indicating little adherence of the dust to the rocks, and a very low ratio of dust mass to rock mass. As for the coloration change over time, I would suspect a uniform coating of dust 10-20 microns thick would be sufficient to mask the underlying color of the rocks. This suggests the slope is actually very active with these features.

My wife thinks they're stretch marks. No comment.

[DaveBone]

The underground liquid theory seems unlikely given the atmospheric pressure and the prevailing temperatures on Mars, yet the points made do seem to match the picture pretty well. This is one where I'd have to say "show me the proof" before fully accepting the explaination. Good interpretation though.

[The Code]

There are lots of weird pic,s of mars. Hard to explain.

Check these: http://www.starrycritters.com/tag/mars- ... e-orbiter/

Who knows how they Formed? Beats me.

Enjoy

Mark

[orin stepanek]

Because of what appears to be darker material; I wish we could pan over toward the lower left corner of the picture. There seems to be a flat area there; and it seems to be quite a bit darker.

http://hirise-pds.lpl.arizona.edu/PDS/E ... browse.jpg
I was trying to see if the dark material might be pooling at the bottom; but I can't really tell!

[DonAVP]

There are lots of weird pic,s of mars. Hard to explain.

Check these: http://www.starrycritters.com/tag/mars- ... e-orbiter/

Who knows how they Formed? Beats me.

Enjoy

Mark

Mark

Thank for the LINK . Very beautiful images. Did you select the full screen mode at the bottom of each image? You can zoom in and out with you middle wheel button. Very COOL!

Don

[twfeline]

If these were avalanches, they would tend to flow around heights and the flow would narrow as it coursed through depressions between higher objects.
-They would pool somewhere eventually, at least in some cases.
-Some of the streams would fan out, especially when they reached the bottom of their flow.
-The area they pulled away from would be one color and the material doing the flowing would be a different color (even if slight).
-You would see these all over the planet, and not just in or next to a few or new craters.
-The area at the top of a flow would in some cases be fan-shaped.

I'm leaning toward the idea that there are fissures under the crater and liquid water is oozing up through the fissures, causing the staining.

When the crater was formed, it created and/or tapped into faults down to subsurface water and/or water ice, which sometimes liquifies during a combination of high surface temperatures and subsurface upwillings of heat.

It's typical of some materials to get much darker when they are wet.

The old stains are white, indicating the deposit of water-soluble minerals (salts) drawn up with the liquid water, which then turns the surface white when the water evaporates. Eventually, the white minerals are covered or scoured by wind-blown dust.

Note that the tops of some of the higher dunes in the dark aread are already starting to dry out, since they get the most wind.

The features are sharply-edged and fine-featured, meaning that the process is in its last stages, with just a tiny bit of water making it to the surface during the upwelling/wicking episodes. When the crater was first formed, there may have been actual pools of water.

The crater is fairly recent (note the lack of craters inside of it). That indicates that it's a short-lived phenomenon, playing itself out over just a few thousand years.

[Frenchy]

Is it possible for Mars to have undergone an atmospheric event/differentiation that might have somehow separated the carbon from the carbon dioxide allowing it to fall to the surface?

[KAMRAMNA]

I pretty much agree w/thongar & redbone. No dark sand streaks. More likley dark (black) material (rock) suface being covered by windblown lighter material (sand). No pellets no oil no liquid and probably no quakes.

[neufer]

My wife thinks they're stretch marks. No comment.

<<Of Interest: Mercury's surface shows many lobate scarps, which are caused by contraction (horizontal shortening) of the crust. In contrast, surface features indicative of extension (horizontal stretching) are rare on Mercury and have been previously identified only within the interiors of four large impacts basins: Caloris basin, Raditladi basin, Rembrandt basin, and a newly imaged basin from Mercury flyby 3. However, MESSENGER's high-resolution images are enabling an examination of Mercury's surface in unprecedented detail, and the above image shows the first evidence of extension outside of the floor of an impact basin. Visible near the center of the image are two narrow, northeast-southwest-trending troughs (orange arrows), interpreted to be landforms created by faulting in response to crustal extension.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/
Carnegie Institution of Washington>>

[blobzilla]

I totally agree with lakeside, this is a liquid, not some black sand,,,,does anyone know what oil looks like,,you know that black stuff,,,looks like a hydrocarbon seep to me. I just joined but have never dared to comment before but i mean this is where they should send a lander cuz something is seeping out from underground and i bet it gonna be surprising.

[rstevenson]

Before we seriously consider oil as a source of the black on this image, you will need to tell us exactly how the oil was created on Mars. Remember that (to quote the Petroleum article at Wikipedia.org) "crude oil and natural gas are products of heating of ancient organic materials (i.e. kerogen) over geological time." So the question is, did Mars have enough "ancient organic materials" to create oil? Think of vast rain forests and vast oceans filled with plant life. Unfortunately, nothing we have found out about Mars so far suggests that that is a likely scenario. Water, yes, and therefore probably (I would say) life of some sort. But it seems not to have lasted long enough to form the sort of deposits of, eventually, oil that you're suggesting are now seeping out to the surface.

There are lots of mechanisms that can create black rock, and therefore black sand. Occam's razor suggests that is what we are seeing in these images.

Rob