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A river runs through it

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#1 Kaelin

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Posted 18 January 2013 - 10:02 PM

Image from Mars appears to show the morphology of an ancient river bed:

http://www.usnews.co...ncy-discover...

#2 llanitedave

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Posted 18 January 2013 - 10:20 PM

What's really amazing is the freshness of the small braided channels along the main riverbed, probably remnants of the last diminishing streams before the whole thing dried up. Makes you wonder how old that particular feature really is.

#3 Mike Casey

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Posted 18 January 2013 - 11:38 PM

Here's a highres image of the floor of Reull Vallis.

#4 Rick Woods

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Posted 19 January 2013 - 01:38 AM

The IAU needs to come up with a new latin term for "river". We see them on Mars and Titan; that should be enough to warrant it.

Say: If this thing is 1000 miles long, 1000 feet deep, and several miles wide, how come it's just now being noticed??

#5 Rick Woods

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Posted 19 January 2013 - 01:44 AM

What's really amazing is the freshness of the small braided channels along the main riverbed, probably remnants of the last diminishing streams before the whole thing dried up. Makes you wonder how old that particular feature really is.


No cratering visible, either..

#6 llanitedave

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Posted 19 January 2013 - 12:38 PM

I wouldn't say it's being noticed for the first time, it just now has a new press release because of the pretty color picture.

#7 David Knisely

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Posted 19 January 2013 - 01:46 PM

The IAU needs to come up with a new latin term for "river". We see them on Mars and Titan; that should be enough to warrant it.

Say: If this thing is 1000 miles long, 1000 feet deep, and several miles wide, how come it's just now being noticed??


Reull Vallis has been known about for many decades. Good images of its detail go back to the Viking orbiters and, contrary to the story line, it was not named by the ESA people. Whether is was actually a ancient river bed or just a valley formed by ground water sapping, glacial action, or sub-surface water behavior is open to some question, since some of its characteristics are not exactly all that similar to terrestrial river beds here on Earth. Mike Carr's book The Surface of Mars discusses the odd terrain in the area in and around Reull Vallis and other "etched" terrain regions on the planet. Calling it a "river bed" may still not be exactly accurate, although I suppose that is still a possibility. Clear skies to you.

#8 llanitedave

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Posted 19 January 2013 - 02:40 PM

BTW, there is some cratering visible in the close-ups -- and interestingly, some of those craters are eroded in reverse, as if the impact hardened the material below it, and then the wind blew away the softer rock around it.

The possibility is also being considered that it is also a glacial channel, and the water flow features are part of its melting outwash.

#9 Rick Woods

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Posted 19 January 2013 - 04:23 PM

Well, we still need a term for rivers.

#10 llanitedave

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Posted 19 January 2013 - 07:00 PM

Arroyo?

#11 stephen63

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Posted 19 January 2013 - 11:01 PM

BTW, there is some cratering visible in the close-ups -- and interestingly, some of those craters are eroded in reverse, as if the impact hardened the material below it, and then the wind blew away the softer rock around it.


I thought those were tree stumps! :foreheadslap:

#12 Rick Woods

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Posted 20 January 2013 - 07:48 PM

Arroyo?


Arroyus! (Has to be Latin-ish, you know!)

#13 llanitedave

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Posted 20 January 2013 - 08:30 PM

Speak for yourself!

#14 Qwickdraw

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Posted 21 January 2013 - 06:50 AM

What's really amazing is the freshness of the small braided channels along the main riverbed


I guess it is a matter of perspective but they are not small. The river is 1,000 feet deep and miles wide maing those braided channels maybe hundreds of feet wide.

#15 llanitedave

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Posted 21 January 2013 - 12:45 PM

True. At one point there was a heck of a lot of water flowing down that canyon. Although it's probable the main channel was never completely filled. Some of the surrounding landscape features look glacial as well, so the more I'm looking at it the more I'm suspecting we're looking at a glacial canyon partly filled with braided stream gravels from the meltwater outwash.

#16 Rick Woods

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Posted 21 January 2013 - 10:18 PM

Speak for yourself!


Que?

#17 derangedhermit

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Posted 30 January 2013 - 11:28 PM

Canali, meaning "channels". Schiaparelli, 1877. Seems to fit.

#18 Rick Woods

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Posted 31 January 2013 - 01:22 AM

Canali, meaning "channels". Schiaparelli, 1877. Seems to fit.


Now you're talkin'! :D






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