Active Mars 1

Az-Dave I've decided to respond to your post in Marathon Valley 2 by starting a new Active Mars topic. Slope wasting is occurring at all three rover sites and is best considered across all three, so its appropriate we move our discussion over here.

You wrote: "There are several images taken over the past 2 years not of dunes, but of areas where the sand had true 100% dry Sand-Slides, in fact one of the images Kye linked to the other day shows both Dark Line-type flows, and a larger same-color sand slides which are clearly not wet."

There are lots of "slides" that involve rigid patches of crust of various sizes that have broken "loose" and moved downslope. These are usually the same color as the surrounding undisturbed sand surfaces. Where sand has recently moved as individual grains it always, in my experience, appears darker than the undisturbed surface and frequently looks darker than earlier slides:

http://mars.jpl.nasa.gov/msl-raw-images/msss/00580/mcam/0580MR0024072170400212E01_DXXX.jpg There's one tongue of dark sand there that's slightly darker than the others, probably the most recent to arrive. Note also that a little more than half the area affected by wasting is intact crust fragments colored like the rest of the slope.

http://mars.jpl.nasa.gov/msl-raw-images/msss/00440/mcam/0440MR1795006000E1_DXXX.jpg There's a big OLD slide tongue in this image running from upper left to lower right, passing behind the rock with a clown nose. It has faded to almost the same color as the rest of the slope. A much smaller, darker lobe extends from the same origin to it's left.

There are "slides" that involve only crust patch movements. There are slides that involve crust movements and sand moving as separate grains, the most common kind at Gale I think. There are slides that involve only sand as grains. Some of these last we call dark streaks, especially if they appear very thin, but other loose grain sand slides have significant thickness and I tend to call these sand streams. I'm not proposing a system of classification here, except as a very provisional strategy. I expect that all varieties are strongly related and that intermediate forms would stymie segregation. There might be definite different types though, but we will probably have to know a lot more to understand why.

You wrote "Sand gets "uphill" by either eroding from even higher rocks, or being deposited there by wind..."

Erosion higher up can't be the source of the sand in any significant quantity because that would imply a rate of erosion MANY orders of magnitude faster than the estimates of Mars science. Remember that this wasting is happening all the time, or repeatedly in a cycle. Its unlikely by definition that we're seeing rare events.
Ahh but wind! Wind is the only available conventional explanation. See Post 0 of Active Mars for an introduction to this topic. I give several reasons there to question the idea that these slides are aeolian slip faces. One I'll reemphasize now: This just doesn't happen on Earth. This being persistent wind driven slope wasting on slopes that are stationary. Persistent sand wasting happens on dunes, and in some special other places where wind is not the driving agent: riverbanks, sea cliffs and termite debris piles, but it doesn't happen persistently on stable rocky slopes. Why would it? The slope would soon become too gentle as sand piled up at the bottom.

You wrote "wind speed far in excess of ANY speed ever recorded on mars is required just to lift the finest of Mars dust and sand (Ames Research required Hundreds of MPH to get talcum powder to move" To get 0.25 to 1mm sand to move requires 250-300mph at the official pressure..."

Right on, mostly, but you are about to explain the contradiction using one of the same mistaken assumptions as NASA. The answer isn't that they're wrong and the air is actually thicker. Seven successful landings speak for themselves. The answer, more likely, is that SAND DOESN'T SALTATE. Dust does get suspended in the atmosphere but its more realistic to think of it as smoke than silt.

I've found that longtime online advocate for a thicker atmosphere. Maybe you have too. I had a brief E-mail exchange with him, but he was kind of rude and seemed very concerned with people's academic credentials. The atmospheric pressure is something that established Mars science probably has right, in my opinion.

I would like to read the content rather than interrupt the lines of thought here, but the HiRISE images show very competent wind blowing and flapping parachutes on Mars from landings, and the 'tell-tail' on Phoenix worked as a wind indicator, even the known process of wind shear and subsequent and unrelated vortex vacuum acceleration has a great effect on Earth and Mars. Why would a general straight line wind average be a source of sole interest?

As dunes are sources of heat retention, and the direction of travel would be upward or downwind, the force applied would be increased.

The self sorting of materials seems very effective in forcing objects into ordered pits and rings as well at the current Curiosity dune location.

HiRISE has resorted to explain gullies in the mid-latitudes as primarily solid CO2 frost and ice 'sublimating' to power air pressure differences sufficient to drive particles downslope, yet the general processes are probably active in mid-latitudes as at Mount Sharp area.
If the materials are tending to self sort and produce pitted patterns in small scale the force would be 'levitating' the top larger grains and allowing pit 'exclusion' in the lower differing material.
Do you want me to display this or should I work on another topic?

http://hirise.lpl.arizona.edu/ESP_044327_1375

The recent HiRISE explanation for active gully formation, lacking the concepts of the sorting and forces I have described as viewable in recent Curiosity images.
It seems they are concentrating on just the 'air pressure' and outgassing as a process of downslope motivation.
I suspect the several concepts are much more active and effective as a system, for upward, horizontal, and downslope movement.

There are some areas of the polar soil exposure which show odd large scale pitting and adjacent peaking mounds as a combination pattern, but I have lost the HiRISE number due to several computer thefts.

Dana re your 1, Thanks for linking that Hirise image of high latitude gully formation and dry ice deposits. Solid CO2 isn't a factor at the low latitude rover sites because the sublimation/freezing phase change temperature for CO2 is in the minus 120's C at Mars pressure, a temperature so low that it is reached only during higher latitude winters. Underground a few centimeters the temperatures at Gale, Gusev and Meridiani would be much higher that the night time lows and even further from the sublimation point, so solid CO2 can't form in the rovers' environs, above or below the surface.

This has got me thinking though, about what I said in my previous post 0, that "Erosion higher up can't be the source of the sand in any significant quantity because that would imply a rate of erosion MANY orders of magnitude faster than the estimates of Mars science." This is clear if we are talking about the the active slopes along the Gale traverse which are seldom more than 2 meters in height. Big slopes like those you posted might sustain mass wasting for a long time without there being any need to explain how the material has been moved upslope. There's plenty of mass wasting on Terran mountain slopes that is being powered long term by tectonic uplift that can be as fast as millimeters per year. In other places on Earth slopes steepened by glacial erosion of valleys are still collapsing after the disappearance of the ice. I wonder though, if anyone is really thinking about the effects of that Martian gully formation over the long term. If we are seeing fresh gullies form between imagings that implies a fairly fast rate of erosion, but the big crater walls on which the gullies are being cut are believed to be very old and otherwise quite inactive, with no known tectonism or galciation to help keep the slopes steep. I wonder if this is maybe another contradiction?

Anyway' here's a few examples of really short active slopes at Gale. These are just a few centimeters high and have no higher slopes above:

http://mars.jpl.nasa.gov/msl-raw-images/msss/00439/mcam/0439MR1790006000E1_DXXX.jpg The slide here is below and left from center (about 3,3 in our 10 by 10 image). This little isolated slope is near Cooperstown where there is much activity on taller slopes.

http://mars.jpl.nasa.gov/msl-raw-images/msss/00696/mcam/0696ML0029480580304243E01_DXXX.jpg The slope and slide are right of center (about 7, 4) between two loose rocks. This one is also appears to be quite a gentle slope.

http://mars.jpl.nasa.gov/msl-raw-images/msss/00646/mcam/0646MR0027470180401903E01_DXXX.jpg The slope and slide are lower left (about 3,3). Again the slope looks like its way less steep than the angle of repose of free sand. What is it that is making this happen?

THere are lots of examples from Gale of short and gentle active slopes. How does it work?

I am slowed by yet another computer theft. A serious pattern has emerged in that regard. Another is on the way to me.
At this public computer, the sol 1270's MAHLI images are showing some very intriguing patterns, and cause me to conclude the impact type forces are involved in the migration of these bright and clay like layers. That is not good for any biology signatures probably, but it was always a possibility that we are deep in the mix of impact dust to clay converted materials.
I could be wrong as is common, but the weave and lacy textures are somewhat obvious a stress/meteoritic induced pattern I believe.
I'll look at your recent choices here and try to catch up yet again.

http://mars.nasa.gov/msl/multimedia/raw/?s=1273&camera=MAHLI

Any of these sols give some of the texture. This is not the best views on this day. They certainly are taking the locale seriously currently.

http://www.planetary.org/blogs/emily-lakdawalla/2011/3144.html

Slope streaks of the large variety, lack of layering, and heavy general deep dusty 'coating' in these craters not near Gale. Interesting concept that Mars has it's secrets large and small.

Leaves open the question of how such soft materials are at the base of massively thick layering in Gale, which may or may not be the remnants of the actual impacting.
Can the textural 'weave' be a product of something other than the high compression and speed of impacts/rebound uplift? Can it be the result of tectonic pressures? A crystalline process caused related to the source? Glacial impact conversion?

I'll try to stick to your topic here now.

Looks to me that these are related to the precise locations and in your third image, the main exposure is 'cleared' of particulates giving the impression that the rock is not the controlling factor, but the wind instead.
In other rover images across Mars where local rocks set with shadowed lower undercut or overhanging 'protected' viewable non-sunlit atmospheric access at the ground surface, I get the impression that the action of removal or dispersal is more active, eroding the undersides greater than the sunlit areas.
Perhaps just an impression from some unusual views.

Something causes the layers of Mars to be very flat other than just wind? Energy re-distribution and more?

I am sure now that I have promised to give some relief from the changing of topic angles and views this new problem I would like to add will be one of my embarrassments on this topic.
This involves todays releases from the HiRISE site additions. It includes two HiRISE images which further show odd activity at either HiRISE, or in the possible mis-interpretations I am making of the HiRISE catalog content generally.
The two satellite views show in one a northwestern area view between the Aeolis Mons(Mt. Sharp), north and probably west of the Curiosity location.

http://www.uahirise.org/ESP_043816_1750

http://static.uahirise.org/images/2016/details/cut/ESP_043816_1750.jpg

The cut-out view here is an extreme full size view of a small crater, floor on a slope, and the center to lower right 'hook' shape showing extruded material overlying the bright layers. The bright layers are dissected, old materials, and are in the crater margin debris as fine materials.
The problem is the tan material which is now layered is clearly weathered and removed from the crater or added and not yet 'exhumed' at the crater bowl. It is directionally similar to the remaining material in the second HiRISE image I will present next.
Does it appear to you that this material is later exhumed subsequent material, or, is this material removed from the crater and added from the 'South' direction(bottom of the cut-out here?
I ask this as the second satellite view is described as having mounded material extending from another crater bowl on the south side of Gale crater, and the materials have a peculiar similar appearance and directional orientation.
The importance of this aspect is only a part of my concern, and seems not related to the matters of slip faces and slides or particulate adjustments, yet I am sure something is described in perplexing terms in these two views. It matches other mysteries about the floor of Gale, the direction of forces, the interpretations of deposits, and the processes of erosion and deposition histories and exhumation both small and large scale.

This now is a view of the second satellite HiRISE image of a crater with floor deposits which reside both inside and outside the crater rim, with continuous directional orientations matching between both deposits.
In the case of this second main image, the introductory description is of a source from the South, entering the crater bowl, subsequently being eroded, and leaving a residual deposit only near the crater and in the crater bowl.
The key is that the timing and simultaneous release of the two gives the impression that the materials are related, but if so, the materials should both be sourced from the South, not from inside the crater, and not a result of the 'exhumation' process of wind removal.

http://www.uahirise.org/ESP_043961_1740

http://hirise-pds.lpl.arizona.edu/PDS/EXTRAS/RDR/ESP/ORB_043900_043999/ESP_043961_1740/ESP_043961_1740_MIRB.abrowse.jpg

Does this appear to you to be related through mis-interpretation by myself or is this a flawed view of the two HiRISE images by the team?

One of many odd aspects of Gale crater information about dark deposits, and layering.

http://spaceref.com/mars/flowing-sand-not-water-source-of-some-recurring-dark-martian-surface-streaks.html

Water, Water Not, Water, Water Not, ...

They now seem to be asking Kye's question. If sand, how does the sand get renewed, or recycled? Why doesn't the available sand get used up? One might also ask why salts have been found in the RSLs.

Where is Kye, by the way?

They are as yet still forwarding research arguing the wet vs. dry flows and RSL processes. Whether the various processes are singular or varied is very important. I distracted Kye too much perhaps in my posts.
The movement of ices, both water and CO2, in the near polar gypsum dunes, is leaving what is now referred to as sublimation till, presumed to be gypsum, and that is one of the few causes for a building process discussed in research apparently. Perhaps I am missing other causes?
The circumpolar process, involved in motion of solids flow and I presume gases with associated transient token liquids, would be most active where ices are concentrated, and not much viewed in the areas Kye is studying. The polar charge water ice effects and other fractures of the equatorial region soils for the three rovers still could be related to minor water content somewhat, I would guess, but fine micron and smaller dust is easily moved with the same processes which suspend it in the atmosphere, I am sure.
The research released which claims a connection between the global dust storms and the loss of gas to space is interesting. A massive change of qualities which we do not see visually.
Would the causes be under the surface, or above?
Frankly, I have viewed fine particles organized elaborately and adjoined in the MER soil which when 'broken' possibly could cause a leveraged avalanche slide perhaps, but we haven't been allowed the view the same assembled material along the path of the MSL Curiosity rover.
Cute blue supermoon eclipse this morning. Watching it through the NASA Griffith Observatory NASA TV video beat the direct view, although I saw the entire sequence directly at the same time. I mention it because I watched the transient clouds effects through the telescope video display. Wisps of water vapor condensation or ice and whatever suspended nucleation items were active in the cloud formations. What would be the differences on Mars for cloud nucleation? An opportunity for the idea of very unexpected causes to be present on Mars, or simple expected causes for motion? Does the daily temperature swing cause the fracturing of crust in soil?
Easier to watch an eclipse by telescope.

https://imageshack.com/a/img924/4773/mE5uAU.jpg


https://www.jpl.nasa.gov/news/news.php?feature=7041

&refresh does work here, to update the prior posts.

This is a HiRISE image of the Jan. 2018 releases, image ESP_052915_2615 , in the cold north circumpolar gypsum dune area, showing the ices are separating and distinguished from the dust and particulates especially where light and radiation is strong but even in the less lighted slopes and crests, giving here an appearance of pooled ice in the brightest elevated sector where the movement of solids has been occurring.
There is an active zone along the brightest area, where blue ice is apparent, with a linear pattern of whiter ice along the lower margin of recent solid material movement. there is a solids margin along the ice periphery, and the impression of separating material types with probable downslope motion of the ice as it seems to be accumulating.
Whether the ice changes state or has a semi-solid movement capability, the displacement or mutual accumulation of solids and ice is apparent.
The gypsum seems to accrue along the ice passage, but none appears here in this closeup.
I am sure Kye would not place this as a primary cause of motion in the rover terrain, but rovers cannot be placed in and on the dunes as yet to look closely for surface fracturing and small sliding, so we have no understanding as to how differing the processes are.

A anigif showing the ice vs. non-ice motion areas, and the distinct color differences of materials. Greatest ice and action at the brightest spot.

https://imageshack.com/i/pm8xC8FGg

4 images, 5 seconds each, about 750kB.

Ices appears to not reside where the solids rest after motion, but are present downslope from the active zones.

What actions are active in the rover paths?

Prior image has a bad HiRISE source image number on it. While I track back that mistake, this circumpolar image of dunes shows a typical series of furrows, downslope paths, and they are at the probable spots of dune debris from rapid slides. We view the active portion of Mars as fractures, furrows or trenches, pits, and other activity in very recent timing. What results in the downslope path activity other than a liquid?
Hydroxide activity, chemical conversion such as ion transfer lanes, carbonic acid and other active chemistry, or are these all the same cause we can view in seasonal and similar time periods? Perhaps some is longer term activity, as these show a substantial volume of rough material at the base of the dunes.
I can accept ice sheets or heavy snowfall, here in these far north images, yet obvious 'gypsum' is claimed at these areas, and it appears under assembly in place, altering and following or altered by the dunes passage at some locations.
Again, what causes the downslope lanes which exit from the rough assemblies of material? Why only the faces and margins of the dunes? Perhaps this is a routine planet-wide process which matches the effects of a liquid transfer across the surface of differing climates?
It seems that some of the basic construction chemistry is available in the near polar realm, but is the active chemistry differing from the heavily iced areas, as in Kye's images?

This image host has discontinued the thumbnail linking code, and I may have to learn to write in code to each image posted.

ESP_052971_2560
Snowy Dunes, at 75.6 Lat 13.5 Long
https://www.uahirise.org/ESP_052971_2560

While we argue the water, no water, discussion, why such large and substantial trenches, even with occasional cones at the trench sources at times? What happens below the dunes and throughout then which results in erosion and deposition of minerals, claimed to be without water or other liquids?
Why would a liquid not be forming in confined areas of ice slabs? Molecular chemistry leading to trench furrows? Another solution which we find across Mars?

A better view of the dunes, but a little less obvious set of trench/furrow type paths away and presumed downslope from the base of the various dunes. Is the transport path chemical, molecular, gas, or liquid?

A closer view at 2 to 1 size from HiView, the bright material is not simply an aspect of the dune, but an assembly with 'lanes' of active distinction leading to further outlying furrows of either freeze fracture of ice as suggested on the HiRISE site or a more active erosion/conversion type process. Continuous travel of non-linear paths, only downslope, and with no massive weighty over burden disruption of the ripples, yet a clear loss of ripples in the furrow depths. Oddly, these furrows exist on the upper sections of dunes, also matching the paths of solids 'lanes' and lower trough furrow non-linear continuations.

A view with higher contrast at 2 to 1 size, the limit of clear viewing in HiView. A shame there is no interpolation process in the software that would allow a clear view to 4X.

The mineral 'lanes' clearly connect with the particulate furrows, and as I mentioned on the dunes the furrows are angular and linear typically. Outliers from the dunes and mineral 'solids' are tending to be non-angular and have adjustment accommodations for the terrain.

Activity of several states, or two, or simply a freeze fracturing of differing materials? Would as we see at Gale crater and Curiosity there be below ground fracturing leading to these surface differences in materials?
Is the bright material active or are dunes eroding/building the bright material?

ESP_052971_2560

Precise locations and scaling listed on the image host images of large size.

It seems the furrows are often upslope away from the bright material. Some appear downslope, with increased distance from the bright material, and nearly all increase slightly in width with proximity to the bright bacterial. The ripples are eliminated or severely reduced in furrows. Most are sufficiently deep to show shadow on the walls. Most of the furrows have a dark mass of solids appearance at the adjoining to the bright material.
Some of the furrows seem to be active as margins of slides when on steep slipfaces. A percentage of those not on steep slopes also show some evidence of slide or material particulate transport in the merger at the bright material.
From the same source image as the posts just prior, ESP_052971_2560, high north latitude springtime image released this past month, the unique scenes in these dune/bright material images can be confusing about which active processes are viewed.
Below are two spots at adjacent dunes, one showing a couple narrow steep slipface slides where the dune material remains appearing as dune type coloration, but as the particulates transfer to the horizontal bright solid surface, the margin and surface of the particulate is seen as the same color and tones of the solids. A complete change of appearance or a complete elimination of the sliding dark mass has occurred since the slides timing. The slides are at the center towards the right side about halfway down the image. The bright material has either incorporated the dark material and it is changed or efficient removal left a remaining margin of the original content. Material shape or chemical change underway all across this and other HiRISE dune images.

The second image shows furrows alter the ripples, erode the surface, and match dark recesses in the bright material routinely.
The example here shows the furrows sometimes have dark masses where the merger occurs with bright material. These furrows show erosion of the dark mass mounds, giving the appearance of a corrosive liquid or gas, which can remove dark solids effectively. The circular dark by-products are full or partial for each of the two at the center of the image.
The impression I have is the shaded side of the dark mass has been removed in one, with a mystery shape at the other.
Are these closeups which are exaggerated in saturation of color by about ten points in a photo editor showing physical movement and removal, or is this an active chemistry process, with change of dark dune and bright solid material?

Altered appearance.

Active erosion or dispersal or chemical alteration.

Is there enough detail and resolution to see the material altered?
Each small closeup shows a differing activity underway based upon sunlit faces, shaded areas, steep versus shallow slopes, and material type. Both materials are interactive.
Would the subsurface of large and small dune shapes and bright solids be controlled by the same chemistry in the far north as at the rover location? Would similar activity be underway?
I studied the entire source image, a 'NoMap' IRB photo from top to bottom along a center line of X=700. Many intrigues along a single path at size 2.75 enlargement in HiView.
Two obvious sections of dune crest slipface ice is distinct from the bright horizontal solids, and is of a differing color and shape pattern. Both spots are shaded, and the ice has no furrows in association at those spots.

This additional view of the same source, ESP_052971_2560, shows the appearance of ice on the steep dune slope just below the crest of the slip-face, and it is very similar to several other ice pockets on the shaded faces at the same viewing angle. The color of the ice is different than the bright horizontal material, yet has small lobes or petal shapes like this ice section.
This image was taken from the RGB color NoMap image source, whereas the prior images were all from the IRB color image source. The color is reasonably correct for human vision, and seems believable for each material.
The fissures appear on the shallow slopes, in the lighted sides of the dunes, and no or very little ice is seen associated with them. No fissures appear with the shaded ice sections, indicating the fissures are either related to prior fissures in the bright substrate material or to the melting/sublimation of the ice on the dunes lit faces.
Loss of solids along the fissures, and at the interaction zones where the slides cause fans on the bright material.


Despite my attempt, reply #12 has an image of the IRB dune ice, with the artificial color balance of previous images on the topic.
This below is a view of the RGB closeup, at 2x scale, and the color normal for human expectations. Plenty of fan material to view at the bottom of the dune face, yet the ice is separate from the slide debris, no fissures issue to or from ice, and the fissures are active on lighted shallow slopes only.

RGB closeup.

This is out of vertical slice I studied in the prior entries. The location is X 1015 , y 8800 .
The RGB NoMap HiRISE of ESP_052971_2560 again.
A view at 1 to 1, color and contrst adjusted, then a closeup at 3 to 1 size scaling. The object appears at the base of a dune slipface, is a cone or crater with a central pit, and seems to be a portion of the active slipface fan of slides but is also active sufficiently to provide a flat central core with a dark pit, giving the recent activity seen.

The 3x size image.

Nice images Dana!

Thanks, John, I have more from this HiRISE defrosting dunes image, but I was cut off once already for making repeated entries which are not responded to. Your entry helps me to add other detailed closeups. The topic of Kye here was the very small activity and slides which involve downslope movement of particulates or small scale 'mass wasting' type changes in apparent volume and crust breakage in the spots active.
As the difference in ice content, mineral balances and weather are substantial between equatorial rover views and far north ice frosted dunes, I can only show the activity where it is viewable and clear with a presumption that the weather and other chemistry is active in both climate zones. These dunes cover bright minerals which are quite actively influencing the dunes, and the bright material has been 'growing' at the fissure lines, with the shallow dune slopes controlled partly by the fissure patterns, with a massive volume of particulates transferred or removed by the fissures.
The fissures have in most all, a large dark 'pile' or cone at the contact between the bright material base and the thinning dune dark material. The flat bottomed crater shape 3X closeup is an unusually large item at the end or source of a 'desert washout' sized fissure ravine shape, and their is either a central pit opening or a small dark object similar to the dark cones at the crater center. Recent activity on the upper crater wall shows some down-falling slippage where the dune slipface debris would be possibly the most recent activity. There are other apparent possible below surface passage pits in the bright material.
Mass is disappearing on the dunes, with mass at the end or source of the fissures, and a few possible underground pits are viewable in enlarged closeups. Fissure on bright material shows growth patterns from within the fissures at some spots.
I am making images to show those actions.
This area should be re-imaged someday to show the details better. I am sure NASA and other followers of HiRISE are familiar with the activity I am describing. It is important.
There is viewable activity we have seen in Gale crater under some loose rock slabs. The vertical fissures which originate below our viewable surface at MSL Curiosity are often the spots of active slides, and the bright mineral emplaced veins are a near vertical aligned set of fissure type items where Curiosity is traversing.
Erosion or other activity is underway at Gale and movement of mass should be downslope in both climate regimes. The primary difference I can imagine is cold gases from sublimed ice rising along fissures perhaps. If solution of dune mass allows transport of mass towards bright lower elevation dark conical mounds, why no liquids are indicated? If gas arises from dark cones at dune margins and causes fissures to open and erode, where is the removed mass on the shallow slopes?
The HiRISE image suggests a dissolution and transport of mass along the continuous fissures in at least one direction. What if the direction is chemical and transitions in several directions, including below the surface level of the bright mineral mass?
The mechanism on Mars do not have to be unique in each region. The chemistry does not have to be contradicting other regional activity.

Recent comments related to active chemistry on Mars does not contemplate the surface and ground mass interacting with the sunlight, the charged chemistry near the surface, and the effects of polar differences in transport of particulates, even mineral building near the surface.
If there are as appears, underground activity in the dune areas, the causes of action may even be modulated by the amount of energy transition between below ground conditions and sun or atmospheric effects from distant sources.

http://www.marsdaily.com/reports/Leaky_Atmosphere_Linked_To_Lightweight_Planet_999.html

Formation and interaction in the bright materials in the ESP_052971_2560 is not timed my by viewing as yet. Perhaps it is as seasonal as the spiders, fans, and dune ice. Perhaps the system between the equator and near polar realm is a single system?

From reply #11, this is a display showing the bright material is lighted on one side in the mid-afternoon, leaving a shadow side which is active as a slight downslope passage, defined probably by the angles and transfer of material in the two obvious fissures. It appears the dark dune shallow slope may not be sunlit directly, but I cannot tell from this image. The fissures on the bottom of this view, connecting to the erosion zones seems to be two slopes joined by the fissures. The small single dark spot near center is apparently a 'pit' with shading indicating the conical pit depression shape.
The initial image is at reply #11, an altered high contrast view below, with an anigif at 5sec.s, 2 images, of the two image alterations as the final image in the reply.
Substantial material change, loss of blue coloration, loss of ripple surface shaping, removal of mass from the shaded slope at bright elevated sunlit mass, and the separation of large blocks of the bright mass.
The small pit near image center also shows a removal or alteration of the dune slope particulates resulting in erosion with a dark depressed core remaining viewable.
This view doesn't yet show the uprising bright material along fissures, that will be a later entry.


A careful look at the reply #14 image also shows linear ridges in the bright material converging on the central barchans dune spot near the crater shape which has a dark core.