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Author Topic: Why do we always find soft sand in desert ?  (Read 13577 times)

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Why do we always find soft sand in desert ?
« on: 02/03/2009 03:29:20 »
Why do we always find soft sand in desert  ?



 

Offline Don_1

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Why do we always find soft sand in desert ?
« Reply #1 on: 02/03/2009 07:33:57 »
At a guess I would say the sheer volume of sand in one area being constantly on the move ensures that no large particles could exist due to erosion.

But what do I know? I'm no geologist.
 

Offline JimBob

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Why do we always find soft sand in desert ?
« Reply #2 on: 03/03/2009 03:14:50 »
Good guess - probably fairly accurate and when combined with the fact that there is no cementing in the desert sand and no water by which to introduce a cementing agent, the sand is always soft as it is unconsolidated.
 

Offline Damo the Optics Monkey

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Why do we always find soft sand in desert ?
« Reply #3 on: 03/03/2009 04:17:22 »
The answers above a pretty well correct - lack of consolidating agent and constant grinding down by erosion results in fine 'soft' sand.

A similar effect occurs on beaches, just with water adding to the breaking down of the sand.
 

Offline JimBob

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Why do we always find soft sand in desert ?
« Reply #4 on: 06/03/2009 02:01:45 »
The answers above a pretty well correct - lack of consolidating agent and constant grinding down by erosion results in fine 'soft' sand.

A similar effect occurs on beaches, just with water adding to the breaking down of the sand.

Thanks for the vote of confidence.

But actually, a beach is the build up of sand, not the breaking down of sand. Sand is broken down inland, transported to the ocean by rivers through sediment transport, saltation, etc., and then by long-shore current to the beaches.
 
 

Offline Gigacore

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Why do we always find soft sand in desert ?
« Reply #5 on: 08/03/2009 17:44:58 »
Denudation maybe?

Denudation is phenomena where constant erosion and weathering takes place.... since there are enormous amount of sand particles in desert, the denudation leads to fine grin sand particles leading into soft sand overall :)
 

Offline daveshorts

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Why do we always find soft sand in desert ?
« Reply #6 on: 10/03/2009 11:13:17 »
Part of the reason why desert sand is soft is the shape of the particles, as they have been blown around they have undergone thousands of collisions which knock the corners off the particles, so they are quite rounded. Rounded particles slide past each other better than sharp ones so the sand is soft.

Water's surface tension tends to bind the particles together so wet sand sticks together, so if the sand is dry it can be soft.

Saying that there are lots of rocky deserts, few minerals are tough enough to stay as sand for long - most sand is silica - so if the geology is wrong then the sand will rapidly get turned to dust and blown out of the desert, so there are a lot of rocky deserts with very little sand.
 

Offline tony6789

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Why do we always find soft sand in desert ?
« Reply #7 on: 10/03/2009 18:28:39 »
basically the heavier grains sink while the "softer" lighter grains remain on top and blow around...example when u dig in sand it will become thicker and harder to dig the farther down u go
 

Offline Bored chemist

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Why do we always find soft sand in desert ?
« Reply #8 on: 10/03/2009 20:38:33 »
The arctic and Antarctica have little enough precipitation to count as deserts. They are also the two biggest deserts in the world.
Lot's of water, but not a lot of sand.
From the wiki article on deserts there's this quote "Sand covers only about 20 percent of Earth's deserts. "
 

Offline Don_1

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Why do we always find soft sand in desert ?
« Reply #9 on: 11/03/2009 07:48:36 »
If you have the BBC iplayer watch this week's 'Coast'. Sand from Weymouth, Lyme Regis and Torquay put to the test for building sand castles.
http://www.bbc.co.uk/iplayer/episode/b007qb77/b007qb65/Coast_Series_3_Bournemouth_to_Plymouth/
 

Offline itisus

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Why do we always find soft sand in desert ?
« Reply #10 on: 27/03/2009 05:47:56 »
If you have the BBC iplayer watch this week's 'Coast'. Sand from Weymouth, Lyme Regis and Torquay put to the test for building sand castles.
http://www.bbc.co.uk/iplayer/episode/b007qb77/b007qb65/Coast_Series_3_Bournemouth_to_Plymouth/
That video is no longer available, but anyway Lyme Regis is importing sand from France to prettify after the big landslip that deposited a big dump on the beach.
 

Offline Don_1

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Why do we always find soft sand in desert ?
« Reply #11 on: 27/03/2009 09:22:27 »
If you have the BBC iplayer watch this week's 'Coast'. Sand from Weymouth, Lyme Regis and Torquay put to the test for building sand castles.
http://www.bbc.co.uk/iplayer/episode/b007qb77/b007qb65/Coast_Series_3_Bournemouth_to_Plymouth/
That video is no longer available, but anyway Lyme Regis is importing sand from France to prettify after the big landslip that deposited a big dump on the beach.

I blame the parents, you should never let your children have a big dump on the beach.
 

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Why do we always find soft sand in desert ?
« Reply #11 on: 27/03/2009 09:22:27 »

 

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