I wonder what those circular things are that look like vent openings?

Circular things? Not sure what you're seeing here.

Another shot from the same series with a clearer view of that river of dark sand between us and the mountain.
http://mars.jpl.nasa.gov/msl-raw-images/msss/01144/mcam/1144ML0051850260501513E01_DXXX.jpg

All 299 images (so far) from Sol 1144. If you don't want to wait for NASA to do it you can download and piece together a great 360-degree panorama.
http://mars.jpl.nasa.gov/msl/multimedia/raw/?s=1144&camera=MAST_

I wonder what those circular things are that look like vent openings?

Circular things? Not sure what you're seeing here.

William clarified it. He surmised ancient volcanic activity.

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The mind is a weird and mysterious place

At the Bagnold Dunes -
http://mars.jpl.nasa.gov/msl/mission/mars-rover-curiosity-mission-updates/
These are active dunes but the view from orbit shows a lot of bare rock between them. It's not a solid belt of sand that has to be crossed.
http://mars.jpl.nasa.gov/msl/mission/whereistherovernow/

http://mars.jpl.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/01174/opgs/edr/ncam/NRB_501719594EDR_F0511102NCAM07753M_.JPG

Well, it may not be Arrakis but that is definitely some alien-looking sand.
http://mars.jpl.nasa.gov/msl-raw-images/msss/01190/mcam/1190MR0053920330602599E01_DXXX.jpg
As I understand it, the dynamics of a moving dune is different there because the finer dust settles down through the heavier particles instead of blowing along the surface.
But it does look safe to drive on - so far.
http://mars.jpl.nasa.gov/msl/imgs/2015/12/mars-curiosity-rover-track-in-sand-sheet-pia20169-full.jpg

But it does look safe to drive on - so far.
http://mars.jpl.nasa.gov/msl/imgs/2015/12/mars-curiosity-rover-track-in-sand-sheet-pia20169-full.jpg

It's very sparkly, like there's minerals or glass in it.

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The mind is a weird and mysterious place

But it does look safe to drive on - so far.
http://mars.jpl.nasa.gov/msl/imgs/2015/12/mars-curiosity-rover-track-in-sand-sheet-pia20169-full.jpg

It's very sparkly, like there's minerals or glass in it.

Not sure what it's composed of yet, but compared to most Earth sand it's actually pretty dull.
Mars sand -
http://mars.jpl.nasa.gov/msl-raw-images/msss/01184/mhli/1184MH0001630000402969R00_DXXX.jpg
Gobi Desert sand -
https://upload.wikimedia.org/wikipedia/commons/7/7b/Sand_from_Gobi_Desert.jpg

But it does look safe to drive on - so far.
http://mars.jpl.nasa.gov/msl/imgs/2015/12/mars-curiosity-rover-track-in-sand-sheet-pia20169-full.jpg

It's very sparkly, like there's minerals or glass in it.

Not sure what it's composed of yet, but compared to most Earth sand it's actually pretty dull.
Mars sand -
http://mars.jpl.nasa.gov/msl-raw-images/msss/01184/mhli/1184MH0001630000402969R00_DXXX.jpg
Gobi Desert sand -
https://upload.wikimedia.org/wikipedia/commons/7/7b/Sand_from_Gobi_Desert.jpg

Yes, but the other one you posted looked rather exotic:

http://mars.jpl.nasa.gov/msl/imgs/2015/12/mars-curiosity-rover-track-in-sand-sheet-pia20169-full.jpg

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The mind is a weird and mysterious place

Okay. Kansas has definitely gone bye-bye now...
http://mars.jpl.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/01194/opgs/edr/ncam/NRB_503501814EDR_F0512704NCAM00271M_.JPG

Sandwaves.
http://mars.nasa.gov/msl/multimedia/raw/?rawid=NRB_505448420EDR_F0520936NCAM12753M_&s=1216

Hasn't been much to see since reaching the Bagnold Dunes - unless, of course, you really, really like looking at sand...

Sandwaves.
http://mars.nasa.gov/msl/multimedia/raw/?rawid=NRB_505448420EDR_F0520936NCAM12753M_&s=1216

Hasn't been much to see since reaching the Bagnold Dunes - unless, of course, you really, really like looking at sand...

well, you can calculate winds in fluid atmosphere environments & pressures with those dunes...interesting, isn't it?!

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non-profit org. Play4Life in Zagreb, Croatia, EU

I like this~

"Two worlds, one sun"

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The mind is a weird and mysterious place

Too bad there's no auto club on Mars~

Tires showing wear and tear

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The mind is a weird and mysterious place

I like today's APOD, snapped by Curiosity:

http://apod.nasa.gov/apod/ap160720.html

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The mind is a weird and mysterious place

Another good APOD:

http://apod.nasa.gov/apod/ap160824.html

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The mind is a weird and mysterious place