GeologyRocks

Never trust an article that starts "They cannot explain ... " and doesn't provide a reference to who "They" are ...

I spy nutter.

The words "cobblers", "of", "old" and "load" come to mind, but not necessarily in that order.

Plates move via continental drift - adding a weight on top of them (mountain range, ice cap, big pile of sediment) just depresses them (not in the psychological sense ) - isostacy. No lateral movement will (or can) occur as there is no sideways force.

J.

I agree whole-heartedly with you both. Nothing was cited, so I was very weary as to if it were actual researched material or just a bit of crap on the side

I know that some geologists (including an old Earth Systems Evolution prof of mine) have researched continental drift as a cause of 'sliding down' the mantle. Here's what I mean: The position of the Africa plate has changed very little for millions of years, and it's thought to be the central point as to where the break-up began. And when you look at the coast line, the entire continental shelf is exposed. The hypthesis behind this is like sitting something on a hot plate - it will rise due to the heat underneath it. The same idea has been applied with Africa. Hence, some of the other continents broke away and 'slid downhill' as an easy way to put it.. Whether this idea has been confirmed, I have no idea. But I've read some material on it from the past couple years.

But as far as sliding into the depression of glacier? Isostatic rebound happens in 10s to 100s of thousands of years... No where near long enough for continents to move that drastically, as the 'article' suggests.

Not only that, but did you get a look at his site? He has a link to a picture that he claims are islands in some bay that are not really there. The "islands" are clearly low-lying clouds. There are other things on his site that scream "I am a lunatic!" IMHO.

Thanks for the link, though! It was a little levity in my trying day.

Canadarocks

So with all the weight of the ice pressing down on the plate will only depress the plate, correct? But if that the weight of the ice is greater on one side of the plate than the other, it would depress the plate at a tilt. So if the the plate is depressed on a tilt then the heavier end would be pressing against bordering plates with more force than usual. So if the ice began to melt and melts the ice on the higher tilt first the weight on the lower tilt could have the potential to displace with unimaginable force. Im not a geologist, but I know how leverage works, and thats all it is, a giant level.

That's a lot of "Ifs" voltsman01.

1]. You assume that a plate acts as one coherent object, analogous to an iron bar. 

2]. You're discussing vertical forces, not horizontal, so why do you mention "bordering plates"?

3]. Leverage usually requires a fulcrum.

Ben. 

Just to expand on Benault's comment about plates not being coherent objects:  there's evidence after the last ice age in Britain, when the ice retreated there was a certain amount of plate buoyancy adjustment (isostasy) which is noticeable in Cornwall.  However, it only appears to have been a localised event and does not appear to have had any impact on lateral plate movement at all.  In most cases the energy created is absorbed by faults and the elasticity of rocks.

I think OU-Geology_Guy hit the nail on the head right at the start with the wonderful beachball in a swimming pool analogy.

As far as the plates on the earth are concerned there is no 'down' which would lead to sliding around the outside. 'Down' is really the same as 'In'. Remember the geoid!

Regarding the uneven ice sheet I think I see where you are coming from but as Jon points out there is even more mass added to the edges of plates in the form of mountain ranges and to my knowledge there is no evidence that they affect plate movement due to their mass. A separate cause of movement is that mountains have roots and I recall from my degree that there is a theory that mantle convection moving sideways under the plates applies a force to these roots which act in a similar way to a keel on a boat. (Not quite sure how deep these roots would have to be to create a sufficient depression into the asthenosphere for this phenomenon to have an effect.)