Awesome Martian Avalanche. warning large Picture from Mars Reconnaissance Orbiter.

[Ichingcarpenter]

You can see the debris falling down the cliff’s edge (the top of the cliff is to the bottom left of the image, and we’re looking almost straight down the cliff’s face) and then creating a plume of dust at the bottom, hundreds of meters below. When HiRISE took this image, the slide couldn’t have been more than a minute old. You can see that there have been a lot of avalanches here in the past, too. The bottom of the cliff has lots of material clearly deposited by fast-moving falling debris.

http://blogs.discovermagazine.com/badastronomy/2010/03/15/another-awesome-martian-avalanche/


Questions remain about how these dust avalanches are triggered, though it is believed to be related to the spring warming of CO2. You can find out more in Patrick Russell’s caption for HiRISE observation PSP_007338_2640.

http://hirise.lpl.arizona.edu/HiBlog/2010/03/10/springtime-for-avalanches/

[tridim]

1. Something about that image doesn't make sense to me.

I see the dust plume and the cliff, but where is the dust on the cliff? I see no evidence of a dust slide at all.

[Warpy]

2. Yeah, they should have cropped and rotated it

The white stuff is CO2 "snow" on top of a cliff. The red stuff is the cliff face and there are a few obvious streaks of stuff falling down it.

We just don't think of anything falling "up," which is why the photo doesn't make a whole lot of sense. In addition, the snow looks like foamy water at the base of the cliff, not a pack of ice on top of it.

[Ichingcarpenter]

3. This is hundreds of meters below

I think the dust comes from the lowest part of the face cliff which has taken a pounding over the eons
as the CO2 ice falls down the face, the bottom section accumulates debris and finally falls out at the bottom.

From the site:

The image shows the context of where these avalanches occurred, with white boxes indicating the locations of the more detailed image portions shown to the right (all images are false color). Material, likely including fine-grained ice and dust and possibly including large blocks, has detached from a towering cliff and cascaded to the gentler slopes below. The occurrence of the avalanches is spectacularly revealed by the accompanying clouds of fine material that continue to settle out of the air.

The largest cloud (upper images) traces the path of the debris as it fell down the slope, hit the lower slope, and continues downhill, forming a billowing cloud front. This cloud is about 180 meters (590 feet) across and extends about 190 m (625 ft) from the base of the steep cliff. Shadows to the lower left of each cloud illustrate further that these are three dimensional features hanging in the air in front of the cliff face, and not markings on the ground (sun is from the upper right).