Interesting Evidence

Trying to collect interesting evidence that could support or refute our theory of RSLs other other theories of RSLs.

Evidence Probably Supporting Cornice Avalanches:

1)   Paths in RSLs can cross.  This works for a cornice avalanche but not for water.
2)   Fixed width paths make sense for snow/ice but not for water.
3)   Steep slopes are needed for avalanches but not for water.  RSLs only happen on steep slopes.
4)   Cornices form near the crests of hills/mountains while other theories could have
       paths start anywhere.  Evidence supports cornice theory.
5)   Looks like white cornices in some locations that go away at other times.
6)   Winds on Mars can be 60 MPH, so even at 1% pressure of Earth there is some force.

7)   There is H2O frost on Mars.

8)   In this paper it says:

RSL fans in Valles Marineris transiently darken during or just after periods of high dust opacity [3], perhaps due to stability of deliquesced liquids into the afternoons when MRO observes. 

     It could be high winds needed to make dust also make bigger cornices.   Or it could be that dust in the air blocks enough sun that cornices build up bigger before melting.

9)  The RSL slopes show lots of erosion as paths are cut into rock and there are large debris fields.
      It would not seem that any fixed amount of ice or salt would be up to the job.  Something like
      cornice avalanches that could go on for millions of years could do it.

10)  Picture of an avalanche on Mars though probably started by CO2 frost and not H2O frost.

11)  Seems RSL more active after big dust storm.    " RSL were apparently more extensive in Mars year 28 (ref. 3 and Supplementary Table 1), after a planet-encircling dust storm started near Ls = 268◦ . To some degree this may be an increase only in the visibility of active RSL, because they have greater contrast with the background when they disturb a bright, fresh coating of dust deposited by the storms. However, RSL growth also continued longer (into early Mars year 29) in the southern middle latitudes9 ."      Recurring slope lineae in equatorial regionsof Mars

12) There is snow on Mars!  (even though I had been told there is not).

       Here we report on experimental evidence that clouds and precipitation play a role in the exchange of water between the atmosphere and ground on Mars. [...]

The Phoenix LIDAR observations have demonstrated that water-ice crystals grow large enough to precipitate through the atmosphere of Mars. In the early morning hours, the clouds formed at ground level and at heights around 4 km because these were the coldest parts of the PBL.  [...]

Eventually the ice clouds would have persisted within the PBL throughout the daytime, and water ice would have remained deposited on the ground. As the depth of the PBL decreased in late summer, this local process would contribute to the seasonal decrease in atmospheric water vapor (1). 

           In the early morning hours on sol 109, the LIDAR observed clouds and           precipitation that extended all the way to the ground (Fig. 2B).

                 
      If there is snow, then it could naturally collect just past the crests of hills making cornices as it falls.   If it were frost there is some question of "could the wind on Mars lift the frost into the air" but with snow, it is already in the air so there is one less potential problem with our cornice theory.

13)  When the ice clouds seem to get snow to the ground is late summer nights:
            "The water-ice clouds were detected at the top of the PBL and near the ground each night in late summer after the air temperature started decreasing."
             
       And from this, the RSLs are active late summer:

              http://www.nasa.gov/mission_pages/MRO/multimedia/pia14472.html

       I think we have our snow just when the Snow Cornices on Mars theory needs it.  :-)

Interesting stuff on RSLs in general

1) "The absorptions observed in CRISM images of Palikir are too narrow to be explained by liquid water. Instead, they may be consistent with hydrated salts (Fig. 1). The rapid change in hydration state of the minerals imply that at the times and places where RSL form, either the hydration state of the minerals is being increased by the presence of RSL, or hydrated minerals are deposited by RSL and later desiccated. A linear spectral mixture of Martian soil with magnesium perchlorate, chlorate and chloride provides the closest match."   Spectral evidence for hydrated salts in recurringslope lineae on Mars

2) Animated GIFs of RLS from http://www.uahirise.org/sim/

Evidence Supporting Flowing Saltwater

1)  Drops of water formed on Pheonix landers legs.

Other Points to Ponder:

1)  Frost forming on low gravity from thin atmosphere could be extra light and fluffy and easier to blow than frost on Earth.
2)  Wind blown dust might push frost.
3)  Other features on Mars are carved from CO2 ice.  Wonder if the CO2 frost was also collected into cornices by the wind.
4) If there are ice clouds near mountain tops it seems that sometimes this ice must land on the ground.  As it lands it might do so in low wind side of mountain top, making a cornice.