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.
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 [u]slightly[/u] 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.
[url]http://hirise-pds.lpl.arizona.edu/PDS/EXTRAS/RDR/PSP/ORB_001600_001699/PSP_001656_2175/PSP_001656_2175_COLOR.abrowse.jpg[/url]
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.