I have seen this type of shaped deposits on icy slopes in past images of Mars. I have never read this confirmed to be one of the many versions of CO 2 'dry ice', nor water ice, and the material always appears transparent or nearly completely water clear.
Is this a type of Mars ice?
The size scale viewed makes the rounded shapes many feet in diameter each, assembled as an oriented formation.
http://hirise.lpl.arizona.edu/ESP_031078_1080
The index page.
http://hirise.lpl.arizona.edu/ESP_031078_1080
The 'Merged IRB' thumbnail image showing the very limited exposure on the upper right of the color strip within the JPG.
The exposure of the 'bunch of grapes' pattern is a reduced tonal set of three small ledges, which actually appear to be recesses with the scarp cliff face. As the material is medium toned and in low contrast, you must search for these with a photo editor to differentiate the tonal qualities. The tonal 'clue' suggests a version of transparent ice with a less than reflective surface, which some 'black ice' and some translucent to transparent silica deposits form as a result of micro or crypto-crystalline patterns found at the surface or throughout.
My request is to identify these as either an ice, or a rocky deposit, and an explanation as to why the only exposures are low in reflectivity yet medium-light in tonal shading.
Some of the material also appears to 'flow' as a transparent 'hoarfrost' equivalent, and that is a process water ice displays. Is the material water, CO 2, or another material appearing translucent to transparent?
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http://hirise-pds.lpl.arizona.edu/PDS/EXTRAS/RDR/ESP/ORB_031000_031099/ESP_031078_1080/ESP_031078_1080_MIRB.abrowse.jpg
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A JPG closeup view, altered in sections to show the oriented assemblies, the flows, and the single masses as a type of limited exposure in an otherwise normal steep scarp slope.
A PNG is side by side with this JPG at the image host.
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Interestingly, some of the lower elevation particulate assembly in the original full frame shows polygon type formation, and dark with brighter shapes similar to relaxed small crater rings. The drainage or transfer of materials and the temperatures should give some of the story, yet the several aspects are a set of indicators to an answer.
Can CO 2 ice permeate or transition through solids in layers on these slopes or can water ice do that?
Can massive ice deposits form in limited assemblies and grow in size to these shapes?
Are these alcoves and gullies formed by the same materials we are observing in this closeup, and does that become a standard process of gully formation on Mars?
Posting the closeup B&W displays a rather poor quality view of the flows and less obvious rounded shapes, so I will present a different image soon. Looking to the left of the two alteration boxes, the pattern is easy to see, and nearly appears as the cliff face of solid rock.
The far right altered box has a distinct 'flow' down the cliff face beyond the narrow ledge deposit.
It is best to view these in a JP2 viewer at original quality.
It appears from color stills that the rounded and very oriented pattern on the far left side of the prior images is in other colors than infra-red, actually a continuous scene of the sheeted, patterned repeats of the main body of the icy scarp slope. I believe it is worthwhile to study the reason for the difference in characteristic shapes of the oriented and repeat sharp edged shapes. In the IR gray-scale image, the largest file and the most detailed usually, the roundedness could be a measure of a surface of ice over solid ciy rock or more opaque ice/dust.
The veins and lodes of ice or other material which can be seen across the scarp slope are different at differing elevations, different angles of incidence, and possibly different solid materials.
It is common for the veins and recesses to be well oriented in one to several directions,
I have presented below small caves or deep recesses of crater shapes, vein linear removal crevice/recesses or caves, and find that these are all above the steep alcoves and gully formations midway down the scarp/cliff face.
It appears some ice gathers or appears from some source within a number of the sharp edged craters on the slope, but other craters have no visual ice in blue color.
The craters with deeper dark recesses seem to have no blue coloration, but the original images may not have a correct shadow color balance, therefore the blue may be hidden if present in the examples here.
Extreme lightening of the images shows the reddish shadow color of the originals. That also is causing much of the pink to reddish tint in the atmosphere as well, in other imaging from the HiRISE and rovers. I will watch for additional examples at this location for a color balance basis.
The anigif below is of the blue icy shallow ledge of the topic images through entry #2.
I see in the RGB image the angular non-rounded sections of the routine surface pattern where a rounded cluster appears in the grayscale.
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The overview in grayscale as an anigif. The upper shallow ledges, with craters and veins/deposits from upper to mid-range, and the alcoves and gully formations at lower elevations. Below the bottom of this frame are floor deposits with unusual pond or crater patterns. Material is well differentiated in some. The originals are well worth studying.
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This is one of the shadowed recesses which are at the crater shapes. Some of these are at blocky rises which have recesses apparently. It appears some may be deeper than the visual lighting allows us to see.
Some of these are found at or have caused linear vein or fracture lines and intersections. Removal of the fracture/vein materials appears to be the cause or result of crater formations.
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Another oriented recess at a crater location. These show that the craters and the vein/fractures are related, with the recesses related to at least some of the craters.
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Other anigifs of differing image numbers and timing will be found adjacent to these images.
Does this show that the deeper recesses are caves or evacuations of fracture/veins? Which caused the other?
How much gas release occurs or occured at the recesses over time?
Two stills of the rounded oriented cluster, and of the dark shadowed recesses.
The dark spot in this view is at an intersection of the vein/fracture sets, and is a minor physical cause potential for the massive oriented veins along which it occurs. This suggests the crater recesses may be caused by activity in the fracture/veins.
The idea of deep activity in recesses or caves along fractures or veins is common for Earth, but on Mars it is sought as an indicator of geological potential not usually seen at the surface.
Was liquid or gas active in the development of the structures, and is the scene similar in appearance to that of active time period the occurrences?
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Waiting for an anaglyph of the scene someday.
An addition to the examples of recesses on the upper scarp elevation, well above the alcoves and gullies in the mid-range of the full image. This is an anigif of about 2.7 MB.
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A collection of shadowed 3D aspects of the scarp patterns. These are mostly not deeply recessed, but have connectedness to the veins, fractures, or layer deposits residual in the obvious multitudinous patterns of layers in the slope.
Any recesses are unexpected on an active scarp slope of mainly particulates and ice. Any possibility that there are deep recesses and cave like structures from some processes in the region?
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Again the blue of ice deposits is not present in appearance in these recesses. Is that significant? Does ice have a place in the formation of the recesses and the upper scarp erosion?
Is this not an area of the image where ice is active, other than the visual obvious shallow ledges of the topic closeups?
Is ice an atmospheric addition to a slope only?
Are the alcoves and gullies lower in elevation conditioned by the veins or fracture patterns above, or, are the two visual processes differing materials in erosion with unique features on a slope?
Recent news not directly related to the craters and recesses on the cliff face. These are active crater pits where elevated peaks should usually be formed. The answer suggested for pits is ice and water rapidly exploding as a gas. Suggests smaller craters may be similarly caused.
http://www.sci-news.com/space/article01012.html
Pockmark craters in the shallow sea around very active tectonics movement zones. The answer near these Ne Zealand offshore zones is methane and other gas release in rapid and massive quantity.
http://www.sci-news.com/othersciences/geophysics/article00985.html
A few closely related facts and concepts from recent science news articles.
http://www.sciencedaily.com/releases/2013/04/130426115449.htm
http://www.ch.cam.ac.uk/news/small-not-insignificant%E2%80%A6
http://faculty.washington.edu/ghp/researcthemes/water-science
The movement of materials in low energy climate is seen in water ice, and types of 'hoarfrost' movement occurs in the polar and circumpolar regions. The concept of a thin film of water versus a solute or solution type of water occurrence is suggested by the filling of veins and fractures across Mars, and formation of lodes of subsurface ice.
We expect frost weighted particulates can transfer material on slopes. In this HiRISE image we see bright polygons at low elevations well below veins and crater/pits. Areas of ice or frost or dust, adhere to the mid-range of the slope, and appear isolated from the slope materials in the image colors.
Formation of erosion alcoves with gully formations attached occur in the mid range between veins and crater/pits, and lower bright polygons, with the blue material separated slightly from the alcoves/gullies.
A complex series of formations are seen as a system of movement despite measurement of apparent low energy in the temperature and atmospheric pressure figures.
http://lptms.u-psud.fr/membres/trizac/Ens/L3FIP/Ice.pdf
http://en.wikipedia.org/wiki/Regelation#cite_note-5
http://en.wikipedia.org/wiki/Mpemba_effect
No links on brine effects were included here as yet. The fact that two chemicals concentrate in solution as temperature of liquid water drops to freezing and below was not introduced as yet.
I do not see liquid visible flow on the slope.
Dana/Hort
I am about to publish an article with one of your images with your approval. After a temporary publication on the net I will be able to post a link for your review and approval for context.
Thanks fred