GeologyRocks

Depends on what you actually want realism wise. Desert sand (dry) won't hold a boot print or type track perfectly and will kick up a lot of dust (more so with large vehicles). Many deserts have a surface crust and boots may make no impression.

Spreading sand won't alter its properties much. Moisture content will.

If you want tyre tracks and boot prints and no dust I'd use sharp sand and keep it slightly damp - you could always cover the surface with a thin layer of dry playsand or sliversand for a better surface effect.

Expertise: Professional geologist/geophysicist with field experience in the Atacama desert.

You could always experiment on a beach!

As Hypocentre says, wet sand holds the best boot print, dry sand will hold an indentation (at best). Sand refers to a grain size. I assume when you say sand, you mean sand-sized grains of quartz. You can have very coarse sand (~1.5m diameter grains) all the way down to very fine sands (~0.075m diameter grains). I would expect perfectly dry, very fine sand to be kicked up into the atmosphere and produce a bit of dust, depending on the speed of the vehicle (I think a wind speed of 20km/h will lift a 0.1mm grain into suspension). But then coarse sand would not be so easily put into suspension; hence no dust cloud.

Moving and sifting sand is unlikely to produce any finer grains (unless you really go at it and whack it with hammers or something!). However, I think it highly unlikely you could wash and sieve several tonnes of sand and get it all the same grain size...

to save you days and tons of work i would advise going to the next sand pit and ask how much it would cost to buy some cubic meters of sand of a special grain size.

to cleanly sort them you might likely need a flotation device and sedimentation basin (i am not sure on the correct english terms for these).

Thanks for the advice, but this is purely an intellectual exercise. Is it possible to come to any definite conclusions about whether dust clouds would be seen in the scenario given? Yes, no, impossible to know without experimentation, or some other answer?

Cheers!

transportation and dumping the sand will not be enough to cause dust creation unless you had a very dirty an dusty transport container.

driving a vehicle thru it will not creat dust either (unless you repeat the process insanely often to grind down the sand grains)

also, if the sand has been washed and sifted that it won't form dustclouds it is also unlikely that it will hold a footprint or tiremark. you will only see an impression but with no details. the shape of the grains might influence this though. i can imagine having perfectly rounded grains compared to very angular ones will make a difference. dont know how big this will be though. however, for building sand castles sand that is very angular is used bc it holds better together. usually (as a vague rule of thumb) river sand is often more angular than beach sand.

the creation of dust requires a certain grain size that is to my knowledge (i am not a sand nor dust expert) below the grain size of what people like you and me would consider sand. you would likely require a minimum amount of silt (unsure) or clay particles that are sufficiently small to be able to be suspended in the air for some time. also these particles must be really dry. if there is some moisture or even water there will be no dust, only mud or dirt.

you could test this by dropping different samples into a column of water. sand and silt to some degree will sediment pretty quickly clay particles on the other hand will need very long and are also light enough to be uplifted by small turbulences in the water. this isnt a good scientific explaination i think but image your water is now the air.

i am certain you could create an experimental setting with different grain sizes and controlled sample and air humidity(should affect dust creation, too).

I agree with the other posts.

In essence you would need perfectly dry uncompacted fine silty sand and a high speed vehicle to kick up a dust cloud that would be visible.

But to have the sand hold a boot print or tyre mark then the sand would need to be slightly wet.

Unfortunately physics means you can;t have it both ways. The best analogy is building sand castles on the beach. If you use the dry sand from high up on the beach then your castle will collapse straight out of the bucket. If you use the slightly damp sand then it will hold it's shape (until it dries) and if you use the fully saturated sand it will slump out of the bucket again.

Shame it's a purely hypothetical excercise - use it as a good excuse for a day at the beach!

Thanks to all of you for your answers.

Just in case you were wondering, this is to do with a debate I'm having with someone who is a proponent of the Apollo Hoax conspiracy (i.e. men didn't land on the moon).

He's entitled to his opinion of course!

HLAR 

Now you tell us. This changes everything because much of the lunar surface is material which is finer than sand grade (and will take a boot print)

lunar dust is also highly electro-statically charged due to radiation bombardment. this will make creating dust harder. also the dust there (NOT sand) is able to be suspended in "flight" because of strong electro-statical interactions.

tell us some of your frieds arguments - i am sure we can rip all of them apart.

I'm the friend he was talking about.

 This is the thread we were discussing.

http://apollohoax.proboards21.com/index.cgi?board=theories&action=display&thread=1194111920

 We were discussing it at the "Loose Change" website.  The thread on which we were discussing this disappeared but I started another thread.  We mentioned this discussion here.

http://z10.invisionfree.com/Loose_Change_Forum/index.php?showtopic=19386

 What does everybody think?  Were those pro-Apollo people right when they said that just transporting and placing dust-free sand would cause enough erosion to create enough dust to cause a dust cloud when the sand is driven over?

As has been said, washed and clean sand will not erode just by moving it. Sand has a high surface area to volume ratio (at least if it's sub-rounded or better), which makes it stronger against breaking. But also, it is nearly impossible to fully clean sand.  You can wash it and wash it and there will likely still be some dust left, hidden in small pits on the sand surface that stuck to the sand when wet but when dry may fly away.  Also, the water you use to wash with likely has dust particles in it as well (unless you use distilled water or something), which will be on the sand grain once the water evaporates off, not to mention any dissolved elements that solidify once the water is gone.  This is why you get water spots when you clean your car and why your car actually gets dirty when it rains.

However, the size of the sand plays a large part in whether it is able to be kicked up or not. Fine-grained sand or smaller would probably stay in the air and go high enough to make a sort of "cloud," but it wouldn't stay in the air any longer than it took the sand to just drop back down, I don't think it would stay suspended. if there was silt mixed in and maybe a small draft in the room, that may suspend for a small time.

And for the record, I think the moon hoax is a stupid idea. If we didn't land there in the 60's, we could have easily gone back by now. But why haven't we gone back? Because we don't need to, we've already been there, and the moon isn't complex enough to waste more money on because the first mission told us as much as we wanted to know.

Thanks for the reply KU40.

 The point is that those people who said it was impossible to sift and wash some sand to make it dust-free and then place it and have a track of sand that would not raise a dust cloud when the sand is driven over were wrong whether or not the moon missions were a hoax.

Here is a thread I started on the moon hoax if anyone wants to join in.

http://forum.sbrforum.com/politics/49943-did-we-really-go-moon.html

Pardon me for a second gents, I have to rant about something that just boils my blood because I hate whiners. It has to do with where all of these conspiracy theorists live. There are these people who are absolutely adament about the US government being liars and who just want to defraud and take advantage of the citizens. But where do these whiners live? The US! And what do these people do every year in April?  Pay taxes to that government!  Isn't that ironic?  If you hate our government so much, why don't you MOVE. Stop wasting your time and your life trying to prove these things and save your mental sanity and just get out of here so you can stop worrying about it. I've never understood this.

I can understand how you feel KU40.  I used to believe everything the American press said too.  I lived in Latin America for almost four years in the eighties and I learned a lot about what the US government does.  I've been living in Madrid since 93 and I hear the same stories here.

This site gives a good idea of what's going on.

http://www.thirdworldtraveler.com/

That experience enabled me to be objective when I saw evidence that the government lies to its citizens. 

Here are some videos that talk about some of the lies we hear.

http://www.question911.com/linksall.htm

If you want to discuss the evidence I posted about the moon or the other issues, we can do it in this section.

http://www.geologyrocks.co.uk/forum/general

Just a gentle reminder folks that is GEOLOGY rocks - a website devoted to geology.

By all means discuss whether the transport of sand can generate silt/clay grade material but conspiracy theories belong elsewhere.

Please do not make me get the moderator's red pen out.

Sorry hypo, I didn't realize this wasn't in the off topic section as I just go to the recent posts link.  This topic doesn't seem to have that much to do with geology anyway, I wouldn't feel bad if you moved the thread over to the OT section because of the revelation of the idea behind the question.

 Not that I'll take this any further.  I don't like talking with people who put words into my mouth.