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July 14, 2012


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Georgia is a great name for a geologist's daughter. Would the vegetation reduce the average mobility of the sand? Or do cause and effect work the other way round?

I was beginning an unrefined search for some climate info on the area, and found some pictures of the Bore along with a custom interactive map and the local weather.

Maybe the sand is constantly weathered from laterite?

But no one wants to talk about wind. Here http://www.anra.gov.au/topics/rangelands/overview/wa/ibra-gd.html#climate there are some interesting bits, but the site is not updated and has broken URLs to another gov site where an economic bent prevails and finding data is not a promising prospect. (Correction: A bunch of 404'd links to other gov sites.) It's just like looking for something like specific LandSat imagery from the US gov. :D

Uh, so did you think it was windy? The windspeed is 4 kph at the moment, but you had a longitudinal sampling of greater duration. ;)

I think I get better results from "Gibson+Desert"+paleoclimate and "Gibson+Desert"+aeolian+processes. Let's see how much of it is behind paywalls, shall we?

Ha ha! From Wikipedia:
This section requires expansion. (July 2012)
See also

Hey, somebody just realized it should be there. That's good.

Hi R and F - thanks for the comments and the ideas - and the research. I suspect that the relationship between vegetation growth and sand mobility is a complex one, a variety of the chicken and egg thing. Vegetation certainly reduces mobility, but the opposite is also true - mobile sand prevents vegetation gaining a hold. My guess is that the initial vegetation got going during a time of climate and aridity change, with perhaps sufficient rainfall during the transition to stabilise the sand and allow seeds to get a grip. If this has been a cyclical phenomenon from more to less to more arid, then the totally unvegetated periods when the sand was on the move may have been relatively short, and the grains did not have time to become appreciably rounded (it's a slow process).

I can get pretty windy out there today - there were a couple of occasions on my trip that watched grains on the move, and I can verify that saltation is a global phenomenon. But I would also suggest that the total distance any individual grain travels is short, before it gets buried in a sand drift against a bush. And distance travelled is an important factor in grain rounding.

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