re: North polar geysers?
You might be right. But the image was not supposed to be of active geysers.
The south polar geysers are also not supposed to be "caught in the act".
Their eruptive nature is deduced from the fan shape of the deposits.
Here is a close-up posted to the Markcarey.com/mars/ forum:
Notice all the fans seem to be across the tops of dunes. Also, interesting is that they all seem to be formed by a round deposit on one side and the fan is created by wind blowing the dark material onto the other side.
Can't say this supports a geyser origin, but what could be the origin of the round deposits on one side of the dunes?
Bob Clark