Re: Could this be a snow-line on Mars?
At 48 degrees south latitude, it is within the range that ice is predicted to be stable on Mars.
And as this temperature map shows, at this latitude daytime summer temps can exceed 20 degrees C, 68 degrees F :
South Polar Cap Recession
http://www.mars-ice.org/spole99.html
Then it may be possible for liquid water to form here for short periods during the summer daytime.
Bob Clark