On the Road Again - volume 8 - Page 11

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Barsoomer


Posts: 344

Reply: 201



PostPosted: May 14, 2011 2:21 AM 

Trench in the side of a low ridge or ripple (near the bottom right).

hortonheardawho


Posts: 3465

Reply: 202



PostPosted: May 14, 2011 9:43 AM 

DOH!

I finally figured out why my reply 182 distance calculation was so wrong: I used the sol 2589 images - not the sol 2592 images - to calculate the "previous" parallax measurements to crater Skylab.

Say, doesn't anyone ever bother to check my numbers? Are you all on a conference call to Philadelphia?

hortonheardawho


Posts: 3465

Reply: 203



PostPosted: May 14, 2011 10:46 AM 

sol 2595 berry "parking lots":

with location links.

How "regular" do these patterns have to be before there is a need for an explanation?

It is now sol 2596 15:02:31 and today's drive should be complete.

Fred


Posts: 73

Reply: 204



PostPosted: May 14, 2011 11:49 AM 


I think anyone can clearly see that material has been moved around the polygons. This is at least gas emissions and probably periodic liquid. Of course we must remember that those who would say, cannot say because they could be wrong. To ignore is safer.

Ben


Posts: 5

Reply: 205



PostPosted: May 14, 2011 12:02 PM 

Barsoomer; Don't you think the "bedrock" is tilted upward(toward the left) beneath this ripple and openings in it are allowing dry dust to fall in the cracks .

Hort ; I think we we consider you the Captain so no need for us to navigate Laughing

Could be a berry riot attempting to remove their despot leader Wink

Barsoomer


Posts: 344

Reply: 206



PostPosted: May 14, 2011 4:08 PM 

Hort's 203: There seems to be increased erosion of outcrop in places that have a greater covering of berries.

Ben, yes, that seems plausible regarding the bedrock tilt.

Fred


Posts: 73

Reply: 207



PostPosted: May 14, 2011 4:22 PM 


Dust falling through cracks will not align berries in straight lines or clear them away, water would.

hortonheardawho


Posts: 3465

Reply: 208



PostPosted: May 14, 2011 4:26 PM 

sol 2596 ( May 14, 2011 ) R0 Rear Hazcam:

and R0 Forward Hazcam:

Based on these images - and drive indexes and drive times, my guestimate is the sol 2596 drive was 160+ meters - with a brief stop at the crater ahead ( Puerto Williams? ) for a quick L257R2 panorama followed by a long autonav drive.

Kye Goodwin


Posts: 1166

Reply: 209



PostPosted: May 14, 2011 5:38 PM 

Horton, re your 203, and the berry parking lots. I heartily agree that the distribution patterns of the loose berries are extremely orderly and complex, very much in need of an explanation.

All I can do is try to chip away at the widespread indifference to the current processes that result in this beautifully complicated planetary surface.

For a few months now I've been looking at the erosion of the bright rock with a new general idea in mind: All the erosion takes place while the rock is covered in soil. Perhaps the ideal situation involves a thin layer of spherules and finer soil a few mm thick, to produce the optimum Martian climatic conditions for chemical erosion. In this image a neat oval of dark soil stands out in the interior of a block of bedrock. Look left of and just below center:

The oval does not reach the edges of the block leaving a bright margin around the block. Now look lower and left of center in the image, where a dark-surfaced interior covers most of a block partly surrounded by a narrow raised bright rim, a condition we have seen a lot of along the traverse. Of course the most obvious interpretation is that the depressed areas of bright rock are more likely to accumulate soil and hence become covered. I'm thinking that covered areas are more likely to become depressed by erosion than are exposed areas, that is, that the causation is reversed or perhaps involves a feedback loop. It is interesting then to see that oval of dark soil developing and creating a bright margin apparently before a depression develops. The berries in your "berry parking lots" (203) in places form neat lines parallel to the edges of blocks leaving a bright margin without spherules.

Serpens


Posts: xxx

Reply: 210



PostPosted: May 14, 2011 10:46 PM 

Could be a berry riot attempting to remove their despot leader

Say, you could be on to something there Ben. But if you look real close they are carrying tiny placards ‘Mars for the Martians’ and ‘Go Home Yank’.

On a serious note, the forces acting on these spherical berries are aeolian and gravity. High spots have only a few, still embedded berries while eroded out berries accumulate in low spots and along the laminar ridges.

Ben


Posts: 5

Reply: 211



PostPosted: May 14, 2011 11:07 PM 

Kye; Are you saying that some process(chemical) is deepening (eroding)the depressions beneath a thin soil layer. This causes the berries that are released by the "erosion"to become concentrated in the depression and remain after the soil is blown away. ?? Possible but maybe a bit too compex.

I am not sure the accumulations are that "orderly or complex" because the heavier berries ,over time,will tend to accumulate in any depression no matter how it forms.

I can see how surface winds could actually accentuate depressions in the soft rock,by rolling the harder berries around; similar to pot-holes developed by turbulent water.

Just another view based on the info we have.

Ben


Posts: 5

Reply: 212



PostPosted: May 14, 2011 11:23 PM 

Serpens; I hadn't seen your 210 before I posted and wasn't being rude.

On another related topic which Kye has noted is the fact that the "bedrock" appears to rise beneath the linear dunes as possible low amplitude ridges.
Upon further examination I agree with this observation and would now pose the question.

What created this ridge and swale phenomena and did it cause the ripples or are the ripples protecting the ridges and allowing the swales to be eroded. (chicken &egg) Confused

Ben


Posts: 5

Reply: 213



PostPosted: May 14, 2011 11:39 PM 

Serpens; After noting your comment on vertical release artifacts. I began to wonder if the circular features I have called "dust mesas" ( and which we have yet to see up close) may be similar to exhumed ,mud diapers !!

Serpens


Posts: xxx

Reply: 214



PostPosted: May 15, 2011 1:28 AM 

I think it is possible that the sedimentary rock between ripples could have eroded down a bit while the ripples protected the underlying surface. But I am not sure that there is any bedrock rise under the ripples other than the odd protuberance that we have seen on dune free bedrock. Close to craters apparent bedrock higher up in dunes is probably due to ejecta fragments.

Those circular features look like old filled then uncovered craters to me. Possibly impact into the original wet sediments which then filled with ‘different’ sediments that became slightly more indurated. Or you could be spot on. Need ground truth to tell and with the current obsession to drive, drive, drive I doubt we will even get a decent image.

Tim Demko seerms to agree with you of soft sediment deformation but thinks that these examples are probably caused by gravitation effects such as slumps on slopes and buoyancy/loading and tectonic forces since the laminations below the folded bed in the rock are relatively undeformed. I wouldn’t like to second guess Tim and so my flood plain/delta hypothesis just moved further to the far right of the probability distribution.

Kye Goodwin


Posts: 1166

Reply: 215



PostPosted: May 15, 2011 4:06 AM 

Ben, re your 211, I guess there are just two processes that can move the berries, in theory, without going beyond the "mainstream": wind and gravity. The larger berries, say 3 to 5 mm, would be heavy objects to move even in Earth winds and must be near impossible to shift under Martian conditions where winds twice as fast as the highest ever observed on Mars (around 100 km/hr by one of the Viking landers) would be necessary even to mobilize 0.1 mm particles.

But let's assume that this does happen, anyway. What would we expect to see as the result of such a storm? The loose berries have somehow managed to be present everywhere without apparently accumulating anywhere. After all this distance across Meridiani we still haven't seen a single example of a pile of loose berries, not a single depression full of berries, not a single drift or tail of berries against a rock, and not a single granule ripple made up of berries, Somehow they always manage to form a layer on surfaces, of soil or rock, that varies from a monolayer spaced apart, like Horton's berry parking lots, to a monolayer close together. I just can't believe that if the berries move in the wind that this would be the outcome. Wind movements would strip this thin layer of berries from some locations and pile them in others, and that would be it for berry movements until it happened again. These thin uniform distributions of loose berries would never be re-established. The aftermath of a violent storm would look completely different from what we see and leave plenty of evidence of berry movements that would persist for a very long time.

On the other hand, if the berries are released from the rock by some gentle sort of erosion and never moved by wind, that might be a better explanation of why they are so evenly spaced across the landscape, assuming that their distributions in rock are similar everywhere and erosion is similar everywhere. I think that there are lots of problems with this idea too, like why we haven't seen colluvial fans of spherules where they are in theory eroding from crater slopes, but at least the overall large-scale distributions might be explained if the berries are not wind mobile.

hortonheardawho


Posts: 3465

Reply: 216



PostPosted: May 15, 2011 9:04 AM 

sol 2596 ( May 14, 2011 ) L257 "stamp" of "Puerto Williams" inserted into "stamp" navcam frame:

Oops. Looks like the feature "Puerto Williams" was the trench feature NE of the sol 2595 position and was photographed before the sol 2596 move. This throws off my timeline reasoning about the drive, so I am revising the distance down to 120+ meters.

It is now 12:45 LST of sol 2597 and today's plan includes the next drive direction panoramas, a 360 degree L1 pan, another twilight L7R4 sequence and tau measurments.

Hopefully, some of the backlogged color images, including the above one, will be downlinked.

Barsoomer


Posts: 344

Reply: 217



PostPosted: May 15, 2011 1:53 PM 

Kye, I think you are assuming that the wind would have to pick up the berries and deposit them elsewhere like it does with dust. If that were the case, one might expect the phenomena you describe. But I think Ben is suggesting something else: the wind _rolls_ berries like marbles. From that perspective, one would expect monolayers to persist. It is a lot easier for the wind to roll massive spherical particles that it is to move them like dust.

Ben


Posts: 5

Reply: 218



PostPosted: May 15, 2011 2:01 PM 

Kye; I didn't mean to imply that the wind moves the berries any great distance.
My idea is that the white beds are quite soft and easily eroded which sometimes forms shallow depressions.

The berries released in the erosional, creation of these depressions are then swirled about by the wind .
This swirling of the harder berries further erodes the depression releasing more berries which are captured and concentrated as shown by Hort's images.

This process is visible in desert areas , is very slow and may take hundeds of years

Kye Goodwin


Posts: 1166

Reply: 219



PostPosted: May 15, 2011 2:59 PM 

Barsoomer, re your 217, I'm assuming that the berries would have to move by creep, rolling or reptation (synonyms), if they could move at all, and that mode of movement would be particularly prone to create concentrations of berries, almost immediately that the process started, in my opinion. Suspension might produce a fairly uniform layer of dust, but sand saltation and granule creep create ripples on Earth. Rolling across the surface, spherules would be blocked by many obstacles, and soon start to build ripples where earlier blockades start to catch more particles. That is how it works on Earth.

Ben, re your 218, You "didn't mean to imply that the wind moves the berries any great distance." Yes, but it seems to me that any wind movements of the spherules at all would leave evidence of those movements, particularly as local accumulations more than one spherule deep, something we have never seen. I've been hoping that someone would object to this observation, on the grounds that there could be lots of images of deeper spherule deposits, but one would expect all but the surface layer to be hidden. And I agree that this would USUALLY be so, but we've seen a lot of rover disturbance, deliberate and accidental trenching, and the impression that there is just a surface layer of berries has been confirmed every time. The rover tracks always show that berries have been pushed down into fine material underneath and almost removed from view. This would probably not be so if a deep deposit of berries were to be infiltrated with dust, filling just the spaces between the spheres. By now we should have seen an example of spherule pea-gravel somewhere, but such such concentrations don't seem to exist. And then there's all the images acquired on the crater slopes inside Endurance and Victoria, places where it is really hard to imagine spherules moving without moving downslope and forming typical gravity accumulations. None are seen.

John Henry Dough


Posts: xxx

Reply: 220



PostPosted: May 15, 2011 4:23 PM 

if berries are round and magnetic,,,and there are other magnets nearby,,,as far as we know,,,,could the sand be magnetic?.
Mars is red rusted iron,are we equipped to notice electromagnetic responses on a 'berry' scale?
Thinking out-loud,
Thanks to all this Talent!!!!!

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