Trek to Mount Sharp - Page 31

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Posts: xxx

Reply: 601

PostPosted: March 15, 2014 10:48 AM 

Winston: Bingo! The two white dots are most curious.

Looking@Mars: The black dots are dead pixels in the MAHLI CCD. They appear to move because the two images have different pointings.

Meanwhile, Curiosity is rushing towards Kimberley:

Sol 0569 panorama ( HD format ) 200 meters from Kimberley:

with a link to the full panorama and from there a link to a map location. Looks like Curiosity is back on track to Kimberley. Another week or so?

Kye Goodwin

Posts: 1166

Reply: 602

PostPosted: March 15, 2014 3:48 PM 

Hi Wildcat, You're far more willing to speculate than I am, but I guess that goes along with your chosen pseudonym. Anyway, its good to hear from someone whose looking at the images. You raise a lot of points, which I'll take in order.

No, I don't think that these little slides are activated by liquid water. This notion is the BANE of slope-streak researchers who have put a lot of effort into seeking liquid water at slope streak sites and so far have "come up dry". The two main streak theories have always been liquid water vs "just" dry avalanching. I think they are both wrong. I've ground-truthed the slope streaks in the rover library and I can see that there is no liquid water involved, but this activity sure is not "just dry avalanching". Material really is coming to the surface at the origin of the streaks and slides, repeatedly in many cases, but its not liquid water. To a first approximation in the rover observations the emerging material is dark sand.

Yes, all the slope activity that I've posted is close to rock, at least at the top of the disturbance, though it sometimes extends far down slope. Usually its just below outcrops, sometimes tight alongside rocks but never on a ripple or dune or a big sand slope well away from rock. This is also probably true for the dozens of sand slide examples that I haven't posted. I'm going to have to go through all my collections again soon to look for exceptions. Exceptions are often revealing.

Yes, the slides usually "quickly come to a halt". Its great to hear one of the generalizations that I've formed but never posted from an independent observer. These little slides have a lot of peculiarities. One is that they often don't get very far from their origin. A crust slab breaks loose, moves a few centimetres downward and then stops on a slope apparently still just about as steep. Frequently dark soil dribbles out from under the shifted crust block. Here's a disturbance that hasn't gone anywhere. ( Lower-left corner, under a rock as usual.) It has burst through the crust on a slope so short that it has nowhere to go.

Mostly, maybe always, the slope activity that I've been collecting is on unarmoured soil. I call the ripples covered with granules 1 mm or greater in diameter, "armoured". The active slopes appear to be covered in finer material.

Yes, the distribution of clean and dusty surfaces in this landscape is a major study in itself, which I've begun. You discuss this image again:

What you write on this topic could be a critique of the notion that there's anything mysterious about that patch of very clean sand beside the rock. Clean patches on the ground next to rock are common at Gale, and the clean (dustless) patches are not always sand:

There's a great clean dark sand slope in that image, but note also the clean patch of pebbles under the left end of the rock overhang. Clearly dustlessness can't always be attributed to recent bulk disturbance, but I'm still very impressed with that first image, because of the sharp line where the dark slope meets the pebbled plain. Usually, as in the second image, the dark clean areas grade slowly into the dusty surroundings.

Thanks for your interest. Keep looking and keep seeing.


Posts: 1

Reply: 603

PostPosted: March 16, 2014 4:51 AM 

I always enjoy discussions of time and geology (or landscape).

The first thing to note is that this is a very ancient landscape, much older than anything on Earth. Thus we need to take into account processes that are regular on much longer time scales, but not common over the 10 year period with the rovers around.

When I was a student, I read a wonderful quotation, I can't remember who by, paraphrased:

"In geological time, the improbable happens frequently and the impossible occasionally".

An example on Earth would be a 1,000 year storm on an alluvial fan sequence. Isn't it more likely that this event will be preserved than the classic uniformitarian model of steady state, say annual storms?

Going to Mars and your argument Kye, there may be periods of higher winds which move the sand around the rocks in images such as in 594. I think this must be the case because otherwise the gravity slips we see now would be more common. Images of Mars show periods where there are storms that last for months. While the rovers have been on Mars, this has not happened. In any case, we are not used to seeing processes that are so subtle of short time periods.


Posts: xxx

Reply: 604

PostPosted: March 16, 2014 11:27 AM 

Sol 0571 albedo changes over 90 minutes:

Red areas got dimmer and blue areas got brighter over 90 minutes. The differences were multiplied by 4 to make the changes more visible.

I was kind'a hoping that the tracks would dim - but for the most part they brightened.

The LST times were 11:40:44 A.M. to 01:08:49 P.M.

Kye Goodwin

Posts: 1166

Reply: 605

PostPosted: March 16, 2014 11:31 AM 

newboy, re your 603, You write, "I think this must be the case because otherwise the gravity slips we see now would be more common." But that's the exciting aspect of this that I'm having trouble getting across: THESE SLIDES ARE VERY VERY COMMON RIGHT NOW. There's millions of them currently active across the floor of Gale. There's been dozens of good examples since Cooperstown and whenever Curi gets near a slope we see more. How much of the floor of Gale are we seeing? Did we land in a place selected for a high probability of sand avalanching? We just have to accept, at least provisionally, for the sake of argument, that these slides are very common and frequent across a wide area, or we're hiding our heads in the sand.

Everybody, think about it, Please.

Kye Goodwin

Posts: 1166

Reply: 606

PostPosted: March 16, 2014 1:21 PM 

I was talking to a friend down the road yesterday and posed the question, where on Earth do we see repeated sand avalanching at the same location. I came up with dunes and cut-banks where water is removing the base of a slope. My friend offered a third type of location, termite mounds.

Those who set out to explain these slides as aeolian slip-faces have some explaining to do. How does the process carry on for millions of years? Its not easy to explain how these slides can repeat and repeat in the same locations through geologic time. And don't try to tell me that they don't repeat. Have they just started up for our visit and now they'll shut down again? The conservative way to approach this is to think, "These slides are most likely normal but there's an outside chance that they're not." To say "This probably isn't normal." isn't being conservative, its being in denial.

Its clear how avalanching can repeat on dunes. Sand comes over the top and builds up on the protected slope. As the slope steepens it becomes unstable and collapses down the face, making the slope overall less steep. Over time the dune moves downwind across the landscape. We've finally found common active slip-faces on Mars, BUT WHAT A SURPRISE, THEY AREN'T ON DUNES, and that makes them quite mysterious.


Posts: xxx

Reply: 607

PostPosted: March 16, 2014 1:48 PM 

Calling CQ, CO, CO. This is a test post on a great board!


Posts: 1

Reply: 608

PostPosted: March 16, 2014 7:00 PM 

Kye, Either there are lots of 'avalanches', or there are not?

What is 'a lot'?

I don't think there are a lot. For me, an entire slope should show disruption if it was 'a lot'.

In the past you have made the point that dunes sensu stricto are seen to be 'armoured', like we saw at Meridiani. No problem with that observation. But here, this is loose fine grained sand/silt grade material, blown up round outcrops in what are semi-stable positions.

I also have a problem with your complaint:" How does the process carry on for millions of years?" Which part of the process - there are a lot of features to be timed; Weathering, dust accumulation, slippage etc.

Much homework required before you can leap to the word 'unusual', bearing in mind my point about available time. With this type of feature, we see what is happening. We must interpret using our knowledge of normal processes BEFORE we need to invoke abnormal ones. I am comfortable with my 'boring' geological observations reflecting geology on Mars, with the proviso that I can't tell you about timing in detail.

So here goes, with maximum not minimum ages. Outcrop weathering - billions of years; windblown sand/silt across weathering slopes; millions of years, up to the present. Most recent deposition - don't know but as I said, we have not seen a major sandstorm since we landed. Slippage on unstable slopes - hundreds of years.

Regarding the slippages, is it possible that the vibrations from the rovers - unique event - are partly responsible?

(This is risky for me because I admit I have done no homework myself but only use geological observation. The rocks and sediments speak!)


Posts: 3062

Reply: 609

PostPosted: March 16, 2014 10:13 PM 

I meant to post these last night but was too tired to do so. Sol 569 has a number of weird rocks and weird alignments of these rocks.

Here's just one example.

My photopage has a few others.

Perhaps Hort would deign to make a sharper image of the above.



Posts: xxx

Reply: 610

PostPosted: March 17, 2014 8:34 AM 

The next section of this topic is Trek to Mount Sharp-Kimberley

I started a new topic because this one is getting rather long and the science stop at Kimberley may be a few months.

Kye Goodwin

Posts: 1166

Reply: 611

PostPosted: March 17, 2014 12:17 PM 

newboy, re your 608, Going to the end of your post first. Yes. sorry, I have a lot of time for this right now, probably more than you do, and I want you to enjoy this as much as I do, since having someone to talk to is good for me. Relax.

I'd have to guess that there's maybe 100 visible fresh little disturbance spots per hectare. That's a wild guess, It could be 1000. I'm trying to get people to understand that this might be important. These little hand-sized events may look trivial to Earthlings, but they just can't be trivial if they're this common and frequent on Mars.

Further, they are MYSTERIOUS, just because they aren't on dunes. You ask which part of the process has to go on for millions of years. It all does. There has to be a cycle of events that completes in a reasonably short time, I'd say a year to at most a few 10s of years, because we know that small disturbances are hidden in that sort of time interval. Otherwise, aren't we saying that these slope disturbances may have taken eons to get ready, and then by chance we've arrived at special time when many are triggering? Isn't that going for the less likely explanation first, when assuming that we have arrived at a typical, common time is more reasonable, because by definition its more likely. To explain this entirely as a wind-powered cycle what we need is a description of how the wind routinely re-steepens all these little slopes. Easy enough with dunes, but here? I don't think there is such a cycle active on mixed rocky and sandy slopes on Earth. Anyone? It's easy to imagine any sort of sand slope sliding once, but then what? How does it keep going over and over so that aliens arriving at a random time are likely to see it?

The rover is probably not responsible for these slides. Some are visible from 10's of metres away, but better yet - there's lots of evidence of older disturbance in the same places as the fresh disturbance.

(Just a point about terminology that you bring up. I'm not calling anything the rovers have imaged a "dune", because I haven't seen any structures with a gentler slope on one side and a steeper slope with slip-faces on the other side. I think that's roughly the geology meaning of a dune. I've been using the word "ripple" for all the "ripple-like" soil structures in the rover images. The ones with granules 1mm or greater on the surface I've been calling "armoured ripples" but I probably shouldn't be implying even that much causality to these mysterious structures. )


Posts: 1

Reply: 612

PostPosted: March 17, 2014 6:10 PM 

"they are MYSTERIOUS, just because they aren't on dunes."
I think this is where the problem with your argument is for me. What is mysterious?

Sand is blown around the outcrop under 'high' winds. This is unstable as 'high' winds do not persist. So in the absence of 'high' wind, they slopes are unstable, and slip. That's it for me.

What is interesting, and difficult to quantify, is why it takes so long for the instability to develop. I think an entire slope will eventually slip, but this is not the case right now in the images we have seen. So even gravity is operating very slowly. Fascinating, but not mysterious.

Before we move on to your challenge of this, it would be helpful if you could respond just on this point above and nothing else.


Posts: xxx

Reply: 613

PostPosted: March 19, 2014 11:47 PM 

Good Evening-

Some great photos coming in tonight. One especially unusual formation- not sure what it is, but I hope we could get a closer look. Note the vertical formation at the bottom left under the rock overhang. It's one of those times where you realize in the photos- we really are on an "alien" world. 8-)


Posts: xxx

Reply: 614

PostPosted: March 21, 2014 12:58 PM 

Oh my.... does anybody else find this photo interesting?



Posts: xxx

Reply: 615

PostPosted: March 21, 2014 1:11 PM 

More "nodules" for lack of a better word, that seem to be broken open. Also note the three pronged structure on the middle left (with a spheroid in the middle of the "hand". And the nodule in the bottom left with a cusped structure. Anybody venture a guess at what we may be observing?


Posts: xxx

Reply: 616

PostPosted: March 21, 2014 1:12 PM 

Here's the photo link that goes along with my comment in 615:



Posts: xxx

Reply: 617

PostPosted: March 21, 2014 9:08 PM 

Claudius, this looks like fossilized reef or corals!


Posts: xxx

Reply: 618

PostPosted: March 21, 2014 10:51 PM 

Someguy---- Exactly! I hope we can get some better/more data that can shed some further light.


Posts: 655

Reply: 619

PostPosted: March 22, 2014 7:24 PM 

Amazing! Looks like a promising story for life on Mars!!!!


Posts: xxx

Reply: 620

PostPosted: March 27, 2014 11:48 PM 

Some great photos on Sol 580.... so much to take in!

One perplexing image: How does a slotted opening in sand stay open??


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