Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: ScientificBoysClub on 02/03/2009 03:29:20
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Why do we always find soft sand in desert ?
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Ftest.scoilnet.ie%2Fres%2Fcrosswords%2Fdesert.jpg&hash=326bf67baab6453526610c68f413c5e2)
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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.
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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.
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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.
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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.
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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 :)
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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.
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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
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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. "
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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/ (http://www.bbc.co.uk/iplayer/episode/b007qb77/b007qb65/Coast_Series_3_Bournemouth_to_Plymouth/)
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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/ (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.
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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/ (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. (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fbestsmileys.com%2Flol%2F4.gif&hash=dc0017defb1737ae43c0ff6efcb35b2a)