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Geology Picture of the Week, June 23-30, 2002
NASA Earth Observatory ^ | 06/26/2002

Posted on 06/26/2002 8:56:25 AM PDT by cogitator

Richat Structure, Mauritania

This prominent circular feature in the Sahara desert of Mauritania has attracted attention since the earliest space missions because it forms a conspicuous bull’s-eye in the otherwise rather featureless expanse of the desert. Described by some as looking like an outsized ammonite in the desert, the structure [which has a diameter of almost 50 kilometers (30 miles)] has become a landmark for shuttle crews. Initially interpreted as a meteorite impact structure because of its high degree of circularity, it is now thought to be merely a symmetrical uplift (circular anticline) that has been laid bare by erosion. Paleozoic quartzites form the resistant beds outlining the structure.

This image was acquired on October 7, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.


TOPICS: Arts/Photography; Outdoors; Science
KEYWORDS: anticline; mauritania; quartzite; sahara
I was having trouble finding a good picture this week until this one showed up today. I wanted to find "geological" pictures of the Iran quake, but it sometimes takes weeks for any pictures of actual ground disruption from quakes to appear.
1 posted on 06/26/2002 8:56:26 AM PDT by cogitator
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To: kayak; Miss Marple; CPT Clay; capitan_refugio; SuziQ; GingisK; Lazarus Long; d4now; Cuttnhorse; ...
*ping*
2 posted on 06/26/2002 8:57:52 AM PDT by cogitator
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To: cogitator
Forgot to mention some nice new Kilauea lava flow shots at the link below. Make sure you scroll all the way down the page.

Eruption Update

3 posted on 06/26/2002 9:06:21 AM PDT by cogitator
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To: cogitator
The concentricity of the uplifted strata is amazingly symmetrical. This suggests to me that there has been a uniform balance of platonic uplift vs. erosion over millennia.

Thanks for a great post.

Barnacle, P.G.

4 posted on 06/26/2002 10:09:41 AM PDT by Barnacle
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To: Barnacle
"platonic uplift"= tectonic uplift?
5 posted on 06/26/2002 11:48:49 AM PDT by slouper
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To: slouper
"platonic uplift"= tectonic uplift?

I hope it wasn't a platonic uplift, I've had too many relationships like that. :D Actually, it might be a plutonic uplift, cxcept they usually don't go in such perfect circles. The Rocky Mtns. are an example of uncovered batholiths, wannabe volcanoes that stopped at depth, and were caused by plutonic activity. Personally, I think it looks like the world's biggest flying saucer finding. (Grin)

6 posted on 06/26/2002 2:01:18 PM PDT by xJones
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To: slouper
"platonic uplift"= tectonic uplift?

...or maybe a Teutonic Uplift.
7 posted on 06/26/2002 2:12:43 PM PDT by Redcloak
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To: slouper; xJones
PLUTONIC uplift.

Oh, the dangers of relying on spellcheck! ;^)

8 posted on 06/26/2002 6:59:08 PM PDT by Barnacle
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To: Barnacle
Hey, I mistyped "cxcept" in my post to you. :)

I've taken a lot of geology classes and we always had jokes about "plutonic" relationships. And the old classic joke was: "You take me for granite, treat me like schist, and that isn't gneiss. [Answer] No I don't, but dolamite." Geologist jokes aren't the world's best. {grin)

9 posted on 06/26/2002 10:05:49 PM PDT by xJones
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To: cogitator
Wow. Very cool. Thanks!
10 posted on 06/27/2002 5:43:57 AM PDT by d4now
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To: xJones
What, you don't like looking for perfect cleavage?
11 posted on 06/27/2002 8:00:25 AM PDT by cogitator
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To: xJones
I think every geology student believes he coined those jokes.

But, actually I did. &;^)

The real difference between plutonic and platonic is that there's no uplift associated with platonic. (chuckle)

12 posted on 06/27/2002 8:16:00 AM PDT by Barnacle
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To: xJones
And remember folks, "Subduction leads to orogeny".
13 posted on 06/27/2002 8:19:48 AM PDT by Barnacle
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To: cogitator
Thanks!!!
14 posted on 06/27/2002 9:14:34 AM PDT by CPT Clay
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To: cogitator
You sure it's not a closeup of a fossilized snail?
15 posted on 06/27/2002 10:47:14 PM PDT by chance33_98
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