Dynamic Planet B/C Question Marathon

[Crazy Puny Man]

@Fozen: I'd like to think I'm kinda good at DP, I was 6th...but Pacific won And took medals in two other ID events So of course he owns everyone's ass

@burrito & ScienceOlympian: for the first part, the answer I was looking for was gravity & internal deformation of ice. I think that's on Wikipedia word for word.

For the second part of the answer, I was thinking (1) basal slip (2) plastic flow (includes plastic deformation, creep, & folding & fracturing) (3) subglacial bed deformation and (4) surges <-- I was iffy on this one. I didn't think surges were technically a WAY that glaciers move, but after taking some tests and going to invites last year it seemed like it was. Also, for number 2 I would've also put stress/strain, and supplied equations for that too, but then I reasoned that plastic flow of glacier ice is due to stress/strain -_- Fail moments...

Pacific, can you confirm/explain if surges are technically a way which a glacier moves?

Also, ScienceOlympian, what you described was plastic flow, and that's due to the structure of ice and weak molecular bonds between layers of atoms of ice, and that's why ice flows, blablabla which is what you were saying I think.

Yes, the top does flow faster than the bottom due to pressure/abrasion, & the middle flows faster than the edges because the edges are thinner & more brittle, and are more subject to friction (in mountain glaciers)

[EastStroudsburg13]

I do not have much experience with Glaciers, but wouldn't pressure be a partial cause of internal deformation?

[Crazy Puny Man]

Pressure is due to the weight of the ice (gravity), the way I see it. The internal deformation of ice accounts for ice's special property of plastic deformation.

[PacificGoldenPlover]

@Fozen: I'd like to think I'm kinda good at DP, I was 6th...but Pacific won And took medals in two other ID events So of course he owns everyone's butterfly

@burrito & ScienceOlympian: for the first part, the answer I was looking for was gravity & internal deformation of ice. I think that's on Wikipedia word for word.

For the second part of the answer, I was thinking (1) basal slip (2) plastic flow (includes plastic deformation, creep, & folding & fracturing) (3) subglacial bed deformation and (4) surges <-- I was iffy on this one. I didn't think surges were technically a WAY that glaciers move, but after taking some tests and going to invites last year it seemed like it was. Also, for number 2 I would've also put stress/strain, and supplied equations for that too, but then I reasoned that plastic flow of glacier ice is due to stress/strain -_- Fail moments...

Pacific, can you confirm/explain if surges are technically a way which a glacier moves?

Also, ScienceOlympian, what you described was plastic flow, and that's due to the structure of ice and weak molecular bonds between layers of atoms of ice, and that's why ice flows, blablabla which is what you were saying I think.

Yes, the top does flow faster than the bottom due to pressure/abrasion, & the middle flows faster than the edges because the edges are thinner & more brittle, and are more subject to friction (in mountain glaciers)

Who woke me up?

I guess you could consider surges to be a form of glacial motion, but I see it as more of a result of basal slip that happens to be cyclical and more dramatic, since essentially surges occur because of regular accumulations of subglacial water.

And yeah it's fine to call me plover.

[Crazy Puny Man]

Or because of mass accumulations.

But yeah, that's what I thought. I mean, my partner thought surges WERE a way that glaciers move, and at one of the invites I went to, surges was one of the answers to that type of question...

Whatever. I know what I'll do with that question now

[PacificGoldenPlover]

Just putting it out there, surges do NOT occur due to sudden accumulation. It would require a ridiculously large amount of snow dropped over a huge surface area. Surges happen due to greatly enhanced basal slip, and relative to the glacier thickness, there really is no situation where basal water pressure could be that much affected simply by accumulation.

In addition, mass accumulation does not explain why the vast majority of surges are cyclical.

[Crazy Puny Man]

Not even through avalanches or landslides? Sure, not too much cyclical, but not even possible?

They also occur due to bedrock failure/sudden slippage...which, to my understanding, is caused by an accumulation of stress in the glacier which can can result from slow-moving ice at the terminus 'damming' up faster-moving ice up-glacier, and the glacier surges once the stress goes beyond a certain 'critical point.'

Could that also (somewhat) explain the cyclical nature of surges too? In certain cases?

EDIT: what is your source(s) for this information? and in general too, if you wouldn't mind sharing xD

[PacificGoldenPlover]

Not even through avalanches or landslides? Sure, not too much cyclical, but not even possible?

They also occur due to bedrock failure/sudden slippage...which, to my understanding, is caused by an accumulation of stress in the glacier which can can result from slow-moving ice at the terminus 'damming' up faster-moving ice up-glacier, and the glacier surges once the stress goes beyond a certain 'critical point.'

Could that also (somewhat) explain the cyclical nature of surges too? In certain cases?

EDIT: what is your source(s) for this information? and in general too, if you wouldn't mind sharing xD

Well, for instance, glaciers are fairly picky as to whether or not they will surge. If a glacier is a nonsurging glacier, then it will almost certainly not surge even if a lot of snow is placed on top of it.

Glaciers surge because stress causes a positive feedback cycle where channels in the ice collapse, forcing the meltwater to travel to the base of the glacier, essentially lifting the glacier up. So, if immediately a after a surge an avalanche fell on a glacier, the glacier would not surge because it needs time for these channels to reform.

It's kind of a chicken-and-egg question. I see where you are coming from, but I still say location, history, and the state of englacial meltwater are all much better determiners for whether or not a glacier will surge.

[Crazy Puny Man]

Not even through avalanches or landslides? Sure, not too much cyclical, but not even possible?

They also occur due to bedrock failure/sudden slippage...which, to my understanding, is caused by an accumulation of stress in the glacier which can can result from slow-moving ice at the terminus 'damming' up faster-moving ice up-glacier, and the glacier surges once the stress goes beyond a certain 'critical point.'

Could that also (somewhat) explain the cyclical nature of surges too? In certain cases?

EDIT: what is your source(s) for this information? and in general too, if you wouldn't mind sharing xD

Well, for instance, glaciers are fairly picky as to whether or not they will surge. If a glacier is a nonsurging glacier, then it will almost certainly not surge even if a lot of snow is placed on top of it.

Glaciers surge because stress causes a positive feedback cycle where channels in the ice collapse, forcing the meltwater to travel to the base of the glacier, essentially lifting the glacier up. So, if immediately a after a surge an avalanche fell on a glacier, the glacier would not surge because it needs time for these channels to reform.

It's kind of a chicken-and-egg question. I see where you are coming from, but I still say location, history, and the state of englacial meltwater are all much better determiners for whether or not a glacier will surge.

Um...I'm not sure I follow you >_> The channels are in the middle of the glacier, i.e. not at the base, right? Also, wouldn't the meltwater travel to the base through moulins? Moulins are how supraglacial meltwater gets down to the base...

Are you saying that the meltwater, instead of traveling through tunnels in the ice, percolate/leak through the glacier and travel to the base? Or that the added stress simply increases pressure & therefore lowers the ice's melting point?

[PacificGoldenPlover]

I will respond on the regular dp thread.

EDIT: Since it has been a while since anyone has posted any questions, I'll post one:

What is the largest nonpolar, non icecap glacier in the world? Which countries is it located in? What is its geopolitical importance, and how is this importance accelerating its retreat?