Naked Science Forum

Life Sciences => The Environment => Topic started by: neilep on 12/10/2009 13:16:54

Title: If I Dig In The Desert How Deep Is The Sand ?
Post by: neilep on 12/10/2009 13:16:54

Dearest Desertologists,

As a sheepy I of course luff to roam in deserts. There's nothing like a good old thousand mile trek in a baron inhospitable desert to start the day !


look, here I am with my bucket & spade



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Me with my bucket & spade

Now then, as ewe can see the desert is a place where there is lots of sand. The sand has been deposited there by sand fairies who take it from beaches around the world. They also sieve it from the ocean using tea strainers.

Say I was on some level ground and not atop a dune...how far down would the sand continue to go should I start digging ?  Is there any soil down there ?  Do different deserts have different depths of sand  ?

Anyway, I'm orf to make a sand castle..I just need some water................DOH !!


Hugs & shmishes


mwah mwah mwah !!




Neil
Sandy Sheep
xxxxxxxxxxxx

Title: If I Dig In The Desert How Deep Is The Sand ?
Post by: JimBob on 12/10/2009 18:24:30

The depth to bedrock varies greatly.  As sand can be blown by the wind, it forms drifts (d'oh) and tends to level out the landscape. The sand fills in the deeper part of the landscape, burying river valleys and all other features. Imagine filling up the Alps so that only mountain tops remain, then the mountain tops are worn down by sand "blasting' the exposed rocks. This is what has happened in some of the older deserts.

The process of sand filling in areas can be seen on Google Earth in northern and northwestern China. There are several areas.  Two I found are located at

43° 07' 58" N   112° 12' 55.76" E

AND

39° 50' 12.2" N  102° 29' 36 E

The last one has a lots of pictures and shows how sand - not deserts - encroach on formerly fertile areas.

Title: If I Dig In The Desert How Deep Is The Sand ?
Post by: neilep on 13/10/2009 13:50:59

Quote from: DiscoverDave on 12/10/2009 16:09:16

I guess the movies about being buried by sandstorms are no joke.  One researcher found a 30 mph wind to blow 6,000 lbs of sand across a 100 foot line in one hour.

http://www.nps.gov/archive/whsa/Sand%20Dune%20Geology.htm

In scientific terms, that’s 2 lb•ft^–1•mph^–1•hr^–1   Whoa!!! 

One reseacher defined sand as between .02 mm and 1.0 mm in diameter, while another used the range of .1 mm to 1.6 mm.  Averaging the two methods, we obtain 0.68 mm per grain.  Then dig a smallish vertical shaft, one grain in diameter, down through the dune until you reach "non-dune".  You'll need to keep count of the grains you remove.  Then multiply the total grains removed by 0.68 mm per grain, convert to the English system if desired, and you have your answer.  [::)] 

I recommend using a hand tally counter for improved accuracy.

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.sieves-india.co.in%2FHand%2520Tally%2520Counter.jpg&hash=6c7ffe369e35a30941d63d0a6afc6bcc)

Thank ewe DiscoverDave ...phew !!..that's a lot of sand across that one line !..was that at ground level then ? ie it's just the sand that crossed the line literally just above it ?.....

I did try to use the hand tally counter but unfortunately it staggeringly lost count after 9999 and so I had to count in my head...I lost count at 10,000....DOH !

Title: If I Dig In The Desert How Deep Is The Sand ?
Post by: neilep on 13/10/2009 13:53:13

Quote from: JimBob on 12/10/2009 18:24:30

The depth to bedrock varies greatly.  As sand can be blown by the wind, it forms drifts (d'oh) and tends to level out the landscape. The sand fills in the deeper part of the landscape, burying river valleys and all other features. Imagine filling up the Alps so that only mountain tops remain, then the mountain tops are worn down by sand "blasting' the exposed rocks. This is what has happened in some of the older deserts.

The process of sand filling in areas can be seen on Google Earth in northern and northwestern China. There are several areas.  Two I found are located at

43° 07' 58" N   112° 12' 55.76" E

AND

39° 50' 12.2" N  102° 29' 36 E

The last one has a lots of pictures and shows how sand - not deserts - encroach on formerly fertile areas.

Whoa !!...Thanks JimBob...Gosh !!...some deserts may well have lots and lots of deep sand then ...I would need at least two hand tally counters then !

Thank ewe very much for the wonderful info.

Title: If I Dig In The Desert How Deep Is The Sand ?
Post by: JimBob on 13/10/2009 17:08:35

There is a little grass left for you to feed on in the last area at least.

Title: If I Dig In The Desert How Deep Is The Sand ?
Post by: neilep on 13/10/2009 18:49:03

Quote from: JimBob on 13/10/2009 17:08:35

There is a little grass left for you to feed on in the last area at least.

yes, yes..I noticed that...and some water too ?

I just luff copying and pasting coordinates into Google earth !

Thank ewe jim