Wednesday, February 25, 2009

Accretionary Wedge - Where would I go... the desert of course!

For the Accretionary Wedge Carnival, we were challenged to make a list of what we felt were the top 100 places to visit for geologists. Well, I’m going to deviate from that a bit. Instead of recommending exact places to visit, as geologists, I think we should be listing features to visit and possible locations where those features can be observed. The point of seeing an example (or several examples) of a feature is to broaden our perspective and make us better geologists.

My contribution to the Carnival this month is to list the deserts of the world and those I have visited. Any one of which would be a fantastic addition to the 100 places to visit. Now, we could get bogged down in terminology defining what is or is not a desert (I have my opinion <200 mm of rainfall/yr, others have theirs), but I prefer to keep it more general.

Why deserts? Well, it may be a little selfish because I study deserts, but it is also a cool place to see some neat geology (and ecology).

Here are the world deserts alphabetical by continent. Extra details can be found at Principal Deserts of the World. (They have a nice table, but didn't want to infringe on any copyright)

Kalahari - Any chance to visit sub-Saharan Africa should include a visit here.
Namib - My favorite desert. This region has been a desert for almost 70 million years. It also contains some of the tallest dunes and hosts diamond mines along the southern coast. I have heard they used to find the diamonds by their reflection in the moonlight. And did anyone else notice the desert scenes in "The Cell" are the Namib desert? Others may have "Shawshank Redemption," I have "The Cell."
Sahara – actually composed of multiple ergs (sand seas). In searching for Where on GoogleEarth challenges, I have often wandered over to Libya. I think Libya has some of the coolest aerial exposures of geology on the planet. Check it out some time or argue for a better location.

Antarctic - In case you didn't already know, this counts as a polar desert.

Arctic - Polar desert.

Kara-Kum - I haven't studied this desert much and it looks like it's wiki page could use some work. If only there were more hours in a day.
Gobi – Actaully, not very sandy. But I would love to visit especially after seeing the Mongolian culture in "Long Way Round."

Great Sandy
Great Victoria
Simpson and Sturt Stony

North America:
Mojave - The only North American desert I have not visited. Bummer, I know.
Sonoran - The Sonoroan Desert is absolutely beautiful and has some of the greatest ecological diversity I have ever seen in a desert.
Chihuahuan - I've driven through much of the Chihuahuan Desert, but never made it into Mexico.
Great Basin - Been through here too, but have not made it to Great Basin National Park.
Colorado Plateau - Yeah, doing field work in this region isn't too shabby.

South America:
Patagonian - "I'm being followed by a rain shadow, rain shadow-rain shadow..."

Specifically, I think everyone should visit a desert with active dunes. Dune fields are excellent places to think about and witness how fluid moves particles. Unless you are watching flume experiments or underwater cameras, it can be difficult to see how water moves particles around. (Smaller particles, there is plenty of video showing debris flows pushing boulders around.) In the desert landscape you can also see how changing wind directions and speeds influence the topography on many scales. If you are so inclined, running along the dune face may produce avalanche deposits and sometimes they sing!

Currently, Nick Lancaster is working on compiling an atlas of Quaternary dune fields. There are hundreds of dune fields (especially if you start counting coastal dune fields) so I will just list out the dune fields I have visited.

Oregon Dunes National Recreation Area - My first dune field visit. Often windy and when the wind really gets whipping, the ankle biting gets intense.
Bruneau Dunes State Park – two really massive dunes that have converged leaving a circular sand free void in the center. Climbing down into the sand free zone is really cool and a little eerie. The GoogleEarth image (I have the kmz but have forgotten how to post it) has very nice resolution, but it doesn’t portray the creepiness factor. The circular floor is a different color (pink gravel), completely calm and quiet except for the occasional grain avalanching of the walls, and often contains a few small carcasses and insects. I don’t spook easily, but this is easily one of the weirdest places I have been.
St. Anthony Sand Dunes - Really beautiful in the winter with eolian snow and sand features mixing. Too bad there is a lot of ORV traffic, especially if they post a wilderness study area sign, grrr.
Coral Pink Sand Dunes Very few camping spots. Try hitting up the undeveloped campsite if it’s full. The pink color is not the only cool part about these dunes.
White Sands National Park What can I say, beautiful and pristine white gypsum sand dunes as far as the eye can see. I’ll post some photos below.

And no, I still have not made it to Great Sand Dunes National Park. It's next on my list!

Heavily bioturbated dune at White Sands National Monument


Microbes living in the moist sediment below the interdune surface.

Surfs up!


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