Telling about the small scale, but still active geological processes on the planet Mars.

1. Active Mars
A Glimpse at the Active Geological
Processes on the Planet Mars
Prathamesh S. Pawar
S. P. Pune University, Pune

2. Processes on Mars
• In past-
• Volcanic- lava flows
• Sedimentary- fluvial, glacial & aeolian
erosional-depositional landforms
• Impacts
• Mass movements- landslides, debris flows

3. …Processes on Mars
• No active geology on large scales
• Considered a “geologically dead” planet until
recently
• Latest technological advancements led to
high-res imaging of Martian surface which
ultimately have led to discovery of active
geological processes on very small scales
• Hence, Mars is active- but on smaller scales!

4. Currently active processes
• Aeolian processes- dust storms- fine sand/dust
deposition as well as deflation
• Mass movements- debris flows, dust/sand
avalanches
• Processes induced by dry ice frost/blocks
• Processes induced by meteoritic impacts
Now let’s take a look at some of the processes…

5. Dust Avalanches
• Most dramatic & rare event
• observed along steep cliffs in North Polar
Layered Deposits and steep slopes of dunes &
craters, happening in Martian summers.
• Triggering mechanism may be defrosting or
meteoric impact
• Freeze & thaw in cracks of loose material may
trigger their cascading along steep slopes.

8. Slope Streaks
• Dark colored streaks upto a few hundred meters wide
& several km long on dune slopes & crater walls
• Mechanism of formation & triggering is debated; may
form by similar processes as dust avalanches
• Most commonly believed to form by down-slope
movement of extremely dry sand or very fine-grained
dust in an almost fluid-like manner (analogous to a
terrestrial snow avalanche) exposing darker
underlying material
• Darkest slope streaks are youngest & can be seen to
cross-cut & lie on top of older & lighter-toned streaks
• Lighter-toned streaks are streaks that are lightening
with time as new dust is deposited on their surface

13. Aeolian activity
• The thin atmosphere of Mars, which is mostly
made up of CO2 , is quite active with its sand
storms & dust devils.
• Fading of slope streaks and rover tracks show
depositional processes
• Solar panels of rovers have been experiencing
deposition as well as blowing of sand/dust upon
them.

14. • Following images show dome dunes in the
Endeavour crater rapidly migrated (4–12 m/Mars
year) in just 2 Martian seasons; some of the
fastest translating Martian dunes detected to
date.

15. • This sequence of images shows the changing
appearance of Victoria Crater (top row) and a
small portion of its north rim (bottom row) with
tracks of the rover Opportunity.
• Strong surface winds during the global dust storm
of July 2007 blew away the basaltic sand making
up the wind streaks

16. Recurring Slope Lineae (RSL)
• RSL are dark debris flows up to a few meters wide
& few hundred m long on steep, rocky slopes.
• Known to be abundant in equatorial regions,
especially deep in Valles Marineris.
• Follow the sun: active on N-facing slopes when the
Sun is to the north of equator; active on S-facing
slopes when the Sun is to the south.
• Important candidate for finding liquid water on
Mars.
• Show depositional fans/aprons at their bases,
unlike slope streaks.

17. Animation of 4
images of RSL in
a crater on floor
of central Valles
Marineris; scene
193 m wide

19. Gully formation & modification
• Gullies on Mars are of great interest as they appear to be active
and resemble landforms that on the Earth are formed by water.
• Observations of gullies during the last decade show that
repetitive activity occurs only during the winter seasons.
• Very slow activity; changes in at least 1 gully observed at about
15% MRO/HiRISE monitoring sites in southern hemisphere over a
period of ~2 Martian years.
• Changes in gullies include channel incision & substantial mass
movements, which are thought to be driven by mass movements.
• Not a candidate for liquid water activity as the gullies seem to be
active only in winters
• Seasonally controlled & correlated with seasonal frost.

20. • This dune gully is found in Matara Crater (50°S). During winter, a
new alcove and channel (white arrow) eroded during late winter,
sending material downslope through the existing channel and out
onto the fan (new deposits are the darker material on the dune
surface). In both larger gullies, the existing channel was incised
further into the apron. Frost coats the dune surface in both
images, but defrosting has begun in the bottom one.
2010-Oct-04
2010-Aug-21

21. • This dune gully is in the northern hemisphere
(70°N). During the winter, a new alcove (white
arrow) eroded during winter, sending material
downslope onto the frost (middle image). Once
the frost had disappeared, the full apron and
channel are visible.
2008-Jul-05 2009-Dec-20 2010-May-12

22. …Gully formation
• Gullies are also thought to be formed on dune
slopes in polar regions because of sublimating dry
ice blocks in summers.
• Sublimating dry ice blocks hovercraft down the dune
slopes carving out shallow, long troughs.
• Gaseous CO2 may act as cushion to the
hovercrafting blocks.
• Over many winters, downhill motion of broken dry
ice blocks can perhaps form the large linear gullies
(some up to 2km long) seen on Martian dunes.

24. Impacts
• Mars is bombarded by around 200 small asteroids or
bits of comets per year forming craters at least 4 m
across.
• New craters are identified by their darker ejecta as
compared to surroundings.
• One of the triggering mechanisms for avalanches
which cause the slope streaks.
• Many impacts expose underlying water ice, helping
the scientists studying about water on Mars.

26. Thank you…
References and Images:
NASA/JPL/University of Arizona
http://www.uahirise.org/