Full Summer:

There are many images such as this, showing the area when the seasonal CO2 cover has fully thawed. Gullies are noted in many locations, each with the characteristic Malin and Edgett geometry of an upper "alcove" with tributary channels. A main channel is incised into the slope with local steep sides, and often a levee or embankment on either side. Then at the base, a distrinutory fan spreads out and deposits the transported sediment at the foot of slope. Often a small cone or fan-delta builds up from the prolonged action of this depositional fan.

One important point to note is that many of the channels contain a ribbon of dark dust, marking the channel itself. On Mars, dark dust is often a sign of recent disturbance (within the last 10 or 20 years). Undisturbed dust gets bleached by the intense UV and solar radiation, while fresh dust surfaces are clearly darker.

We therefore note that it appears that something has flowed down many of the channels in Sysiphi Cavi over the last 10 or 20 years. This confirms the suspicion that Sysyphi Cavi is an area of unusually active and fresh flows. Of course, one can argue that it only takes a mere trickle of dry dust avalanching down a pre-existing channel bed to make the dark ribbons, but we do seem to see this more often here than in similar channels in more temperate regions of Mars.

      Created: May 2002
      Last modified: May 2002
      Authorised by:  Head, Earth Sciences

      Maintained by: Nick Hoffman
      Email: nhoffman@unimelb.edu.au