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The title explains it all. Do objects suspended in ice sink over time? You may remember the story of World War 2 planes that were found 260 ft under the ice which would be anachronistic with seasonal ice layering alone. I'm trying to establish other possible mechanisms. I know that ice flows up and down in glaciers, but will an object actually sink in ice over time?

Also, in what way would they sink? Would heavier parts sink faster than the lighter. Does buoyancy play a role.

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Isn't the title misleading? Ice is a solid, how can something sink inside it? –  jinawee Feb 27 at 18:59
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@MikeDunlavey It seems to be false: physics.stackexchange.com/q/65740 –  jinawee Feb 27 at 19:16
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@jinawee I'm not claiming this for ice or glass but some materials that seem to be solid actually experience viscoelastic creep. See for example the famous pitch drop experiment. –  OSE Feb 27 at 19:41
    
@jinawee Under higher pressure, ice has a lower melting point. Technically if something heavy was placed on ice it could sink in due to this melting effect. If the surrounding climate is below 0 degrees C then as this happens more ice would freeze around the object. Perhaps this could constitute as sinking into a solid. –  wgrenard Feb 27 at 19:46
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@wgrenard: true, but you need a lot of pressure! –  John Rennie Feb 27 at 20:10

2 Answers 2

up vote 5 down vote accepted

If the article you are referring to is this one, then the planes didn't sink into the ice but were buried by blizzards.

Ice does exhibit ductile flow at stress of around 1 to 10MPa, but this pressure is equivalent to around 100 to 1000 tons per square metre and this is far above the stresses normally produced by objects resting on ice. Glaciers flow because the stress is concentrated at the interface between the ice and the rock, and this can produce the enormous stresses required.

So the answer to your question is that no, objects don't sink into ice under their own weight (unless your object is made from neutronium). However freeze thaw cycles can give this impression.

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Interesting. There is a corollary proposed by some creationists that since these plains were covered so rapidly, 260 feet (79.2 meters) in 40 years, certain core samples could not be as old as they are said to be. I was attempting to refute this particular proposition, or at least answer it as honestly as I can. I'm thinking another approach would be the change in density from the surface downward. I doubt it is constant, and I doubt it is linear. Thanks for your help. –  Jordan Feb 27 at 20:54
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@Jordan when it comes to creationists: don't feed the trolls. –  Carl Witthoft Feb 27 at 22:20
    
@Carl, not all creationists are trolls. I consider myself one though I have no problems with evolution or modern cosmology. The Everett interpretation gives me heartburn sometimes, but we'll see how that turns out. –  Jordan Feb 28 at 13:58

I say yes, things can sink in ice. Here's why: there's a thin layer of liquid on the surface of ice that is why ice is slippery. When you put a body on the surface of ice, it'll keep displacing the layer of liquid, getting deeper and deeper, and will eventually sink completely,

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But how fast does that occur? Have there been measurements to determine the rate at which surface displacement occurs over extended timescales? Is it fast enough to explain the depth of the planes in question? Either way, interesting article, +1. –  DumpsterDoofus Feb 27 at 20:34
    
But would this continue to happen when the object reaches the freezing point of water? –  Jordan Feb 27 at 20:40
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@Jordan, the paper addresses the problem with the usual explanation of slippery ice through pressure melting. This liquid layer stays on even at very low temperatures, way below freezing. –  Aksakal Feb 27 at 20:46
    
@DumpsterDoofus, I have no idea how fats this would work. It's probably at the speed of diffusion if not slower. –  Aksakal Feb 27 at 20:47
    
Note that, while it's true that ice cqn develop a liquid layer when pressed, this is not enough to explain why ice is slippery, which is a rather more complicated question. –  Emilio Pisanty Feb 27 at 21:27

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