Fountain of Youth Underlies Antarctic Mountains

New Study Explains Why Peaks Buried in Ice Look So Young

Images of the ice-covered Gamburtsev Mountains revealed water-filled valleys, as seen by the cluster of vertical lines in this image. (Creyts)

Time ravages mountains, as it does people. Sharp features soften, and bodies grow shorter and rounder. But under the right conditions, some mountains refuse to age. In a new study, scientists explain why the ice-covered Gamburtsev Mountains in the middle of Antarctica looks as young as they do.

The Gamburtsevs were discovered in the 1950s, but remained unexplored until scientists flew ice-penetrating instruments over the mountains 60 years later. As this ancient hidden landscape came into focus, scientists were stunned to see the saw-toothed and towering crags of much younger mountains. Though the Gamburtsevs are contemporaries of the largely worn-down Appalachians, they looked more like the Rockies, which are nearly 200 million years younger.

More surprising still, the scientists discovered a vast network of lakes and rivers at the mountains’ base. Though water usually speeds erosion, here it seems to have kept erosion at bay. The reason, researchers now say, has to do with the thick ice that has entombed the Gamburtsevs since Antarctica went into a deep freeze 35 million years ago.

“The ice sheet acts like an anti-aging cream,” said the study’s lead author, Timothy Creyts, a geophysicist at Columbia University’s Lamont-Doherty Earth Observatory.  “It triggers a series of thermodynamic processes that have almost perfectly preserved the Gamburtsevs since ice began spreading across the continent.”

Scientists hypothesize that cold temperatures and high pressures push the water uphill, in the same direction as overlying ice flows. This causes ridgelines to refreeze, thus warding off erosion. (Creyts)

The study, which appears in the latest issue of the journal Geophysical Research Letters, explains how the blanket of ice covering the Gamburtsevs has preserved its rugged ridgelines.

Snow falling at the surface of the ice sheet draws colder temperatures down, closer to protruding peaks in a process called divergent cooling. At the same time, heat radiating from bedrock beneath the ice sheet melts ice in the deep valleys to form rivers and lakes. As rivers course along the base of the ice sheet, high pressures from the overlying ice sheet push water up valleys in reverse.  This uphill flow refreezes as it meets colder temperature from above. Thus, ridgelines are cryogenically preserved.

The oldest rocks in the Gamburtsevs formed more than a billion years ago, in the collision of several continents. Though these prototype mountains eroded away, a lingering crustal root became reactivated when the supercontinent Gondwana ripped apart, starting about 200 millionyears ago. Tectonic forces pushed the land up again to form the modern Gamburtsevs, which range across an area the size of the Alps. Erosion again chewed away at the mountains until earth entered a cooling phase 35 million years ago. Expanding outward from the Gamburtsevs, a growing layer of ice joined several other nucleation points to cover the entire continent in ice.

The researchers say that the mechanism that stalled aging of the Gamburtsevs at higher elevations may explain why some ridgelines in the Torngat Mountains on Canada’s Labrador Peninsula and the Scandinavian Mountains running through Norway, Sweden and Finland appear strikingly untouched. Massive ice sheets covered both landscapes during the last ice age, which peaked about 20,000 years ago, but many high-altitude features bear little trace of this event.

In a 2008-2009 expedition to Antarctica, researchers flew over the Gamburtsevs in a Twin Otter outfitted with ice-penetrating instruments. (Nick Frearson)

“The authors identify a mechanism whereby larger parts of mountains ranges in glaciated regions–not just Antarctica—could be spared from erosion,” said Stewart Jamieson, a glaciologist at Durham University who was not involved in the study. “This is important because these uplands are nucleation centers for ice sheets. If they were to gradually erode during glacial cycles, they would become less effective as nucleation points during later ice ages.”

Ice sheet behavior, then, may influence climate change in ways that scientists and computer models have yet to appreciate. As study coauthor Fausto Ferraccioli, head of the British Antarctic Survey’s airborne geophysics group, put it: “If these mountains in interior East Antarctica had been more significantly eroded then the ice sheet itself may have had a different history.”

Other authors: Hugh Carr and Tom Jordan of the British Antarctic Survey; Robin Bell, Michael Wolovick and Nicholas Frearson of Lamont-Doherty; Kathryn Rose of University of Bristol; Detlef Damaske of Germany’s Federal Institute for Geosciences and Natural Resources; David Braaten of Kansas University; and Carol Finn of the U.S. Geological Survey.

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John F. Hultquist
November 20, 2014 9:40 pm

Time ravages mountains, as it does people.
True enough, but those of use that live in cold places ravage more slowly.

Mark from the Midwest
Reply to  John F. Hultquist
November 21, 2014 5:34 am

Over the past week I think I’m ravaging more slowly, but at a faster rate, (a paltry 29 inches of snow, ytd, out at the gauge in my backyard).

David Ramsay Steele
Reply to  John F. Hultquist
November 21, 2014 9:02 am

Ah, so there you go. You ravage more quickly if there is global warming, yet another price to pay.

November 20, 2014 9:48 pm

Hi all at WUWT.
I have a request to the lurkers, and posters. In a few weeks I have been invited to a PECHA KUCHA. For those who, like me, don’t know what this is: PECHA KUCHA is a presentation format consisting of 20 slides/pictures and 20sec talking pr slide.
Longer expl:
I have decided to use the opertunity to invoke some climate thinking. It will be to an audience of architect’s and politicians, so a good place to invoke thought.
My plan is to show 18 pics from the warmist campaign, iconic and well known, so that the theme will be unmistakeably Global Warming. To the slide show, I will read the story “The Emperor has No Clothes. The last pic will be of the sun.
So my request is as follows: Can you help me find the 18 pics, that best describe “the other side” and the “debate”.
The title of the presentation is so far “Disonance”, but I’m open for suggestions.
Thnks for reading this far ;).

David A
Reply to  Finn
November 20, 2014 9:53 pm
Reply to  David A
November 20, 2014 10:30 pm

First and foremost can I suggest spelling the title of your presentation correctly. Dissonance!

Margaret Smith
Reply to  Finn
November 21, 2014 9:32 am

Finn on November 20, 2014 at 9:48 pm
Hi all at WUWT
On your slides please watch for typos, be sure to close quotes and beware of misplaced apostrophes – all of which appear in your post.
Interesting idea which would make one be succinct.

Robert W Turner
Reply to  Finn
November 21, 2014 9:47 am

First you need to give your audience the proper perspective as to the state of the current climate:
From Roper @ Virginia Tech
You can see that compared to the conditions of previous interglacials we are well within natural limits. Show your audience what the few tenths of a degree warming since the Maunder Minimum looks like compared to the much larger variations throughout time and ask them if they would think the natural forces that caused these large climate fluctuations will be overwhelmed by man’s influence.
I like Dr Easterbrook’s comparison of Holocene temperature reconstructions between the controversial Hockey Stick reconstruction and the more popular reconstruction used by most geologists and paleoclimatologists:
Then you always hear the question, “what if the alarmists are correct, can we afford to take the chance?” Show them these two images:
The areas in red on the second image are the areas that would need to complete major engineering projects to protect cities from flooding under the worst case scenario of sea level rise. The first image shows biomes during the last glacial maximum. You can have a lot of fun comparing these two by doing things like plotting major population and food growing regions to see which climate scenario would have the biggest impact. How much more land is uninhabitable during a glacial period compared to the worst case scenario of sea level rise? Quite a bit. Human civilization has only known warm interglacial conditions and would have no problem adapting to warmer conditions. You can engineer your way around a few meters sea level rise, but how do you engineer your way around the spread of ice sheets and deserts?

Eamon Butler
Reply to  Finn
November 21, 2014 4:50 pm

Hi Finn,
”PECHA KUCHA is a presentation format consisting of 20 slides/pictures and 20sec talking pr slide.”
You say you are looking for 18 slides to show the warmist view, and the last one will be of the sun. That makes 19. You need one more.
I’d suggest you test this out on a neutral person first.I’m not sure it conveys the message quite as you see it.
Good luck with it,

Reply to  Finn
November 22, 2014 12:24 am

DON’T read “The Emperor …..”. It would be a waste of the 20 seconds as no-one would understand why the pictures they are looking at show a clothes-free emperor. We here at WUWT are familiawith the issues so would understand. Your audience I suspect is not already familiar with them, so wouldn’t have any idea of what they are looking at unless you tell them explicitly.
Be scientific. Address the real issue directly for each picture.

John F. Hultquist
November 20, 2014 11:39 pm

Some say perception is everything. After 18 iconic warming slides (what’s 19?) you will have imprinted the AGW orthodoxy. Then the slide of the very warm Sun will convince all that they need to cut their “carbon” output.
If you are not trying to do that – do something else. Each slide could have a left part (most warmists are leftoids) but at the top have the word “wrong.” On the right side, under the word “correct”, show the rebuttal. Done well, in some, you may get a little dissonance.
Example: use the polar bear on ice picture that Gore used. Then take one of Dr Susan Crockford’s quotes and show that it is too much thick ice and not summer low ice that kills polar bears.
With 18 such statements and rebuttals you might make an impact.
The picture of the Sun serves no purpose. Forget it.

Reply to  John F. Hultquist
November 21, 2014 12:01 am

Excellent concept, Mr. Hultquist!

Reply to  John F. Hultquist
November 21, 2014 4:21 am

……penguin mortality and the use of flippertags, walruses hauling out, reindeer populations…..sure there are more! I would use at least 4 animal emotive ones, slide of man in red shorts standing on the ruins of the local store (pacific island somewhere ref a Jai Mitchell post – BS due to island sinking rather than sea level rising). There are many many more.
Trouble with graphs is that they can all be manipulated and modelled – the example above (as I have pointed out before) is for the models inputed to show the most extreme case of RCP8.5. It would be telling if all models were outside the standard deviations of their lines but they are not – so easily disputed. I believe dont give ’em a chance hit them with the easy emotive stuff. Apart from anything else its much easier to find disprove

Reply to  mwh
November 21, 2014 4:23 am

Crikey mod is that the J Mit**** ref, last person I want to big up please delete with a snip if you think thats what Im doing

M Courtney
Reply to  mwh
November 21, 2014 4:28 am

J Mit**** offers a different view. it is not surprising that his comments are of interest. Do you want an echo chamber.
Not that I agree with him on much.

Alan Robertson
November 20, 2014 11:53 pm

The article mentions the role played by the de Havilland Canada Twin Otter, in conducting the aerial research. That aircraft is truly a boon to mankind’s existence at the cold edges of the habitable world.

Dr Paul mackey
November 21, 2014 12:54 am

Here here for the twin Otter. In Scotland it flies a regular service to the Island of Barra from Glasgow, where the runway is the beach. The pilot has to gat a fax of the seaweed and puddles on the beach prior to flight. Perhaps the only scheduled flight (in the UK at any rate) that depends on the tide…..

Otter (ClimateOtter on Twitter)
November 21, 2014 1:07 am

No sign of Shoggoths?

M Courtney
November 21, 2014 1:20 am

Though the Gamburtsevs are contemporaries of the largely worn-down Appalachians, they looked more like the Rockies, which are nearly 200 million years younger.

The reason, researchers now say, has to do with the thick ice that has entombed the Gamburtsevs since Antarctica went into a deep freeze 35 million years ago

This sounds perfectly reasonable.
But there’s something about the numbers…

Dodgy Geezer
November 21, 2014 1:40 am

…“The authors identify a mechanism whereby larger parts of mountains ranges in glaciated regions–not just Antarctica—could be spared from erosion…”
Erosion must be enhanced by climate change – everything is! It is obviously our duty to protect these mountain ranges for future generations – otherwise our children’s children will never know what a hill is!
These magnificent mountains could turn to dust in just a few billion years if you do not act NOW! Please write to your representatives and contribute to my newly-formed Society for Caring for All Mountains . We urgently need to equip our preparatory winter expeditions to Aspen and St Moritz with proper apres-ski wear and luxury chalet accommodation….

Reply to  Dodgy Geezer
November 21, 2014 2:33 am

S.C.A.M. sounds like a fine organization, Mr. Geezer. If you have nifty hats and badges for major donors, I’ll open a chapter here in my neck of the woods.

Reply to  Dodgy Geezer
November 21, 2014 4:19 am

Would that be part of the Caring And Sharing for Humanity organisation that also asks for contributions? Lol!

November 21, 2014 1:53 am

One mistake in the article – the entire continent isn’t covered by ice!
0.03% is dry – so, not quite all ice! 🙂
But often forgotten & an interesting fact.

November 21, 2014 2:30 am

Unfortunately the paper is paywalled and judging “press-release science” is always difficult but from the abstract and supporting information this whole theory seems rather shaky and overblown.
First, nobody really knows how old the Gamburtsev mountains are. They are obviously older than the present ice-cap, but that is all that it is really possible to say. I agree that it is likely that they are quite old, but it isn’t certain. They might be due to intraplate tectonic activity, like e. g. the Tibesti mountains in which case all bets are off.
There are some beautiful radar data in the supporting information which proves what was already suspected, that the Gamburtsevs are quite rugged and have obviously been extensively shaped by mountain glaciation (horn mountains, cirques, hanging valleys etc). So the Gamburtsevs obviously goes back well before the EAIS spread to cover all of East Antarctica. This was at least 35 million years ago, but may be much more. There is growing evidence, particularly from rapid sea-level changes, that there was inland glaciation in East Antarctica much earlier, and it is quite possible that there has been mountain glaciers in the Gamburtsevs continuously since far back in the Cretaceous. I remember several years ago telling a friend who was talking about recovering dinosaur DNA that the high Gamburtsevs is the only place on Earth where he might have a chance to find it, but that they are rather inaccessible.
There is also really no mystery how this rugged topography has been preserved: cold-based ice. A glacier that is frozen to its bed and moves through internal deformation has essentially no erosive power at all. This is well known, and has been thoroughly studied in e. g. Scandinavia where glacial erosion has been minor in areas which have mostly been glaciated by cold-based ice.
One odd thing about thick ice-sheets is that they get colder towards the surface. This is very marked in inland East Antarctica where temperatures at the surface is on average c. -50 centigrade and never ever above -10 while temperatures at the bottom of the sheet is close to zero (and above the pressure-melting point) due to geothermal heat. This means that the higher parts of the Gamburtsevs have cold-based ice, while the valleys and lowlands have warm-based ice with subglacial water being present.
This new mechanism by which water/accretion ice moves away and upwards from subglacial water-bodies is interesting in itself, but I don’t see how it could “protect” the extant topography from erosion in any way beyond “normal” cold-based ice. If anything I would expect it to have the opposite effect. In areas where the temperature is very close to the pressure freezing point repeated freeze/thaw cycles induced by local pressure changes are bound to cause erosion instead.
And, sorry Otter, no antediluvian cyclopean cities or shoggoths are visible in the radar data.

Reply to  tty
November 21, 2014 3:15 am

Quite agree, they must have been glaciated before the ice sheet formed. The other ages are a bit iffy as well.

Billy Liar
Reply to  tty
November 21, 2014 8:53 am

The press release is appalling:
The East Antarctic Ice Sheet, which formed 34 million years ago and at 10 million square kilometers covers an area the size of the European Alps, protected the mountains from erosion.
The Alps are 800 km x 200 km – 160,000 km², nearly 2 orders of magnitude less than the Lamont-Doherty press release.
“It was fascinating to find that the East Antarctic rift system resembles one of the geological wonders of the world – the East African rift system – and that it provides the missing piece of the puzzle that helps explain the Gamburtsev Subglacial Mountains,” said study lead author Fausto Ferraccioli, a scientist at British Antarctic Survey.
“It has been almost a billion years since the Gamburtsev first formed,” said study co-author Robin Bell, a geophysicist at Columbia University’s Lamont-Doherty Earth Observatory. … Between 250 and 100 million years ago – when dinosaurs walked the Earth –the supercontinent Gondwana, which included Antarctica, ripped apart, causing the old crustal root to warm. Reactivated, the crustal root and the East Antarctic Rift pushed land upwards again, reforming the mountains. Rivers and glaciers carved deep valleys and raised peaks to create a spectacular landscape that resembled the European Alps. … The team’s next goal is to drill through the ice and collect the first Gamburtsev rock samples. “Amazingly, we have samples of the moon but none of the Gamburtsevs,” said Bell.
A ton of speculation. No rock samples.
As study coauthor Fausto Ferraccioli, head of the British Antarctic Survey’s airborne geophysics group, put it: “If these mountains in interior East Antarctica had been more significantly eroded then the ice sheet itself may have had a different history.”
Classic climate change meaningless verbiage – ‘if things had been different then other things might be different’. Ya don’t say!
Copy the radar image into Photoshop, re-size the image to be 8 times the width but the same height. This is still not equal vertical and horizontal scale but the Gamburtsev Mountains look just like any other mountains – not sharply pointy at all. Appearance is everything.

Reply to  Billy Liar
November 21, 2014 11:29 am

I suppose they mean that the Gamburtsevs cover approximately as large an area as the Alps which is more or less correct, but I agree that the press release was obviously written by somebody with a rather shaky grasp of geology to put things mildly.

November 21, 2014 2:38 am

Dodgy Geezer says:
“These magnificent mountains could turn to dust in just a few billion years”
You are vastly optimistic. Mountains are geologically evanescent things, they are eroded down to nothing in at most a few hundred million years.
Mountains come and mountains go but plains are for ever.

Tom Moran
November 21, 2014 2:45 am

Bedrock Heat,1-Magik Gas,0

November 21, 2014 3:12 am

But newly formed mountains do not [start] as jagged teeth, that is the result of erosion by ice, ie., glaciation.
These Antarctic mounts were glaciated BEFORE the ice sheet formed so in the first 200million years.

November 21, 2014 3:21 am

So how can I apply this principle to stop myself from ageing?

Reply to  RoHa
November 21, 2014 3:56 am

Put your feet in a bucket of ice water and cover yourself with seventeen thousand tons of snow. That should keep you in perfect condition,

M Courtney
Reply to  Fernando Leanme
November 21, 2014 4:04 am

It worked for Otzi.

Reply to  Fernando Leanme
November 21, 2014 5:32 pm

Not easy to do in Brisbane, dammit.

November 21, 2014 4:44 am

Stone encased in ice doesn’t weather and erode. SHOCKING!

Vince Causey
November 21, 2014 4:59 am

Great, there’s a whole range of pristine unexplored mountains for humans to climb once global warming kicks off!

November 21, 2014 6:18 am

scientists…..over thinking the obvious

November 21, 2014 6:25 am

why must the mountains be older than the ice that covers them? While I would say that it seems likely, it is also possible that the mountains were formed under the ice, pushing them up as they formed. And since the freeze/thaw cycle is very big in erosion, removing the thaw part of the cycle would seem to halt that part of the process. Also, wind-borne seeds sprouting in fissures contribute to the splitting and erosion, so without wind that cause is nonfunctonal. I’m not seeing the amazement factor here.

Reply to  kenw
November 21, 2014 11:33 am

No, the typical glacial landforms (e. g. hanging valleys, cirques) are created by glaciers that only cover the mountains partially, they can’t form under a continuous ice sheet..

November 21, 2014 6:44 am

“If these mountains in interior East Antarctica had been more significantly eroded then the ice sheet itself may have had a different history.”
That is not the statement of a scientist … If and may do not belong in the release of results of a study …

Reply to  JeffC
November 21, 2014 7:26 am

Yes; it does appear to belong to the new ‘cli-fi’ type of scenario’s and seems to imply that this mystery mountain range has kept the ice sheet from sliding into the ocean and drowning us all!!!!

November 21, 2014 7:13 am

The article comments: “At the same time, heat radiating from bedrock beneath the ice sheet melts ice in the deep valleys to form rivers and lakes. ”
Can some geologist here on WUWT tell us:
How much total heat rises up from the earth’s mantle to warm the surface, integrated over all the surface including ocean beds and ridges (both normal bed rock as well all those those sub-sea volcanoes & vents) ?
And is this amount (in Watt’s/m2) figure into the new energy budgets used by the leading Climate models today?
(Because if it is not, and it is significant, it meas their analysis of the energy flows into and out of the earth’s surface, and the heat retaining abilities of the atmosphere are even MORE WRONG, than we knew already).
In particular it means the atmosphere is even less important than we thought for keeping us “warm”.

Reply to  thinair
November 21, 2014 7:51 am

Geothermal heat varies according to location and most goes into the oceans. It is not significant in regards to the big picture. Water under the ice cap must be due to local hot spots such as volcanoes, if there is water.

M Courtney
Reply to  mpainter
November 21, 2014 8:06 am

A possible alternative source of water under an ice cap is molten ice from friction.
Glaciers move and create that melt (usually when the melt has started already).
Does fixed ice on a mountain do the same?
Perhaps, yes.
If their are regular winds over the ice (funnelled by the shape, perhaps) then there would be regular oscillations. These oscillations could cause sweet spots at the bedrock where the vibrations melt the ice.
And once melted, the lubrication would encourage the melt to spread.

Reply to  mpainter
November 21, 2014 11:36 am

No, geothermal heat has large scale effects on ice-sheets. It is the main reason temperatures rise with depth in thick ice-sheets. It may be small (c. 0,1 W per sq m) but a coupole of kilometers of ice is a pretty good insulator.

Billy Liar
Reply to  thinair
November 21, 2014 9:04 am

Here’s a page with info about geothermal heat:
From the paper cited on that site, I think the average globally is ~63 mW/m² – Table 2 p 170 of the paper.

November 21, 2014 8:10 am

As one ascends from the desert and highly eroded and rounded granites of the Mojave up the east scarp of the sierra to jagged spires it is quite clear that glaciers keep mountains “looking young”.
I get tired of hearing that the Antarctic ice sheets are 35 million years old. I wish they were as we might have much older ice cores to work with. They are not. There was an early period when ice sheets developed and then the ice retreated to the mountains until continuous accretion began 14 million years ago.

Reply to  gymnosperm
November 21, 2014 11:48 am

They first reached the coast on a large scale 35 million years ago. They subsequently retreated inland during the Miocene warm period, but conditions in Antarctica remained quite cool and the ice almost certainly didn’t melt completely (the sea-level did not go as high as during the Eocene) and the Gamburtsev mountains would have been the last area to become ice-free. Then, as you say, from 14 million years ago East Antarctica has been continuously ice-covered. But we will probably never recover ice that is nearly that old. Really old ice is only preserved at ice-divides, which are unlikely to remain static for millions of years, and in many areas basal melting slowly removes the oldest ice. Actually the best chance to discover really old ice is probably in the Dry Valleys and similar areas where immobile “dead ice” and frozen soil can be preserved indefinitely.

Curious George
November 21, 2014 9:44 am

That’s a lot of conclusions drawn from what appears to be a single cross section. Is there a side-looking-radar capable of penetrating a glacier?

Doug Proctor
November 21, 2014 10:18 am

I don’t doubt their observations, but, as Diane West pointed out, it is not observations that are a problem, but implications.
I am a geologist, with some practical experience of surface glacial features and processes, so I make these thoughts with some background (which is always open for disagreement).
The erosion of rock by glaciers is a function of the movement of the ice across the rock, through plucking as well as grinding. Major erosion happens at the edges of glaciers where it is common to find crevices at the rock-ice contact. The steepening of cirques and glacial valleys has a lot of this component, leading to big collapse volumes on glaciers (the source of the Okokoks Erratic Grain in Alberta/Montana) and lateral (valley edge) moraines.
Freeze-cracking and gravitational dropping are significant to the “wearing-away” of rock. The usual idea of glacial movement is the “grinding” at the base. Valley glaciers do, indeed, create U shaped lower portions and base by grinding (and plucking) away. It is actually surprising, however, how much surface topography survives on the valley floor, leading to waterfalls afterwards and big ice falls (the Khumba Icefalls of Everest). Grinding at the base is a function of movement, itself a function of gradient of the ice mass and the thickness of ice that is trying, Ice doesn’t move, however, as a block. Slippage planes, detachment surfaces – decollement surfaces in fault terminology – allow portions to move differently, even in different directions. (This is true even for the “till” or common dirt we see on the ground we are farming. Tills show multiple movements of their source glaciers, which happens because the second movement or pulse of the glacier travels on, WITHOUT EXCAVATING what lies underneath, because the dirt is a partial slippage plane). What I suspect here is that there are detachment surfaces within the ice column in this part of Antarctica.
Note that the entire Gamburtsev range is surrounded and covered in thick ice that is at every point thick enough to “move” (flow plasticly) on its own weight-gradient merits. The researchers posit that liquid water moves up and over and “cryogenically” preserves the rock. This would only be a continuous system IF the water that flows up and over continues to move as part of the local “basal” ice sheet. That suggests a detachment plane. What I think is going on is that the deeper ice is NOT moving horizontally (though it may flow up the sides of the valleys, counter-intuitively). I expect there are detachment surfaces up above the mountain range over which the majority of movement occurs. It could be that this top layer and movement suppresses vertical movement up the valley sides.
We then have a two or more part ice movement system. The lower part is static or nearly so, with an active top part. The lower part does not erode the mountains because it is not moving much or at all, and the top part is ice-on-ice and not in contact with the mountain range. We also recall the Lake Vostok et al subsurface lakes in Antarctica: these are static, in basins covered by ice. There must be detachment surfaces above the lakes for them to be static. The principle has already been confirmed.
This is an intriguing situation, applicable elsewhere. We know there is a large, buried river drainage system under Greenland, all deeply below sea level. There may not be as much interior flow as one would commonly expect in an ice-filled basin. Which would mean that at this time Greenland is shedding mostly ice from the top. There is no ice loss from the general mass, but from the top portion only. So to talk about a “collapse” of either Antarctica or Greenland is untenable. Before the basal mass can contribute to ice sheet mass loss, the “cap” has to disappear.
If my thoughts above have a common truth, then it might explain the persistence of the ice sheets: the lower portions, in place, are static, holding up the higher portions above freezing point. A lot of top loss would be compensated for by GIA in the centre, pushing the ice sheet back up, compensating for the loss, and maintaining a snow-to-ice catchment and conversion zone. From what I have seen to-date of subsurface maps of Greenland, this would cover a large area. I can’t comment on the area of bedrock Antarctica that is deeply below sea level and/or in over-ridden, interior basins.

Reply to  Doug Proctor
November 21, 2014 10:57 am

Doug Proctor:
Thanks for sharing your insights. The decollement zones you mention, could these be likened to fluid shear?

Doug Proctor
Reply to  mpainter
November 21, 2014 2:21 pm

Good question, the answer to which may be more an issue of definition than action.
A shear failure in a solid is what we deal with in geology. I don’t believe you can have a shear failure in a liquid or gas or plasma. A plastic substance like ice under pressure might have a zone of rapid change that behaved like a failure plane and look like one after a while.
Shales like the gas zones of the British Bowland Basin will shear horizontally and then the failure plane will shoot up 70 to near 90 degrees. Rock under moderate pressure and temperature with water or hydrocarbon frictional reduction can deform plasticly or fail rigidly. Ice at depth might do both.
I’ve only seen suface exposures of glacial ice, which of course was all brittle at the time. I have seen internal slippage or thrust faults in the exposures, but I couldn’t say if these were plastic failures or just brittle failures.

Dave in Canmore
Reply to  Doug Proctor
November 21, 2014 11:00 am

Very interesting. You say “A lot of top loss would be compensated for by GIA in the centre, pushing the ice sheet back up,” I wonder though, can GIA keep up to a decline? My back of the envelope calculation leaves my in doubt. Seems like you would need a substantial loss to create even 1m/century movement which is a pretty unnoticeable elevation change with respect to increasing the firn line. But I only climb on rocks, I don’t study them beyond where to place my next step!

Doug Proctor
Reply to  Dave in Canmore
November 21, 2014 2:44 pm

Some areas of the western shores of Hudson Bay are still rising 17 mm/ year, some 10,000 years after the end of the last glaciation. In terms of thousands of years, as long as deglaciation isn’t catastrophic, perhaps the GIA is significant.
What was the rate of initial subsidence and that of recovery? Never worked it out if it is even possible to work out or determine from geology.
A review of Lake Vostok is in order. Is the ice on top stable? If it isn’t, the microbial community in the lake will be only as old as the cycle time of ice from the top to the bottom. I think the word is that the lake is many millions of years old, which means thete is a detachment plane and “cap ice” above. Which is proof of concept for my speculation about Gamburtsev.

November 21, 2014 11:58 am

Actlually GIA can only partly compensate for ice-loss since the rock is much denser than ice. Also there seems to be two components to isostasy, one “fast” that is a purely elastc rebound and one “slow” that depends on mantle material flowing back into the depression left by the ice. The latter is still quite strong in Scandinavia and around Hudson Bay more than 10,000 years after the ice melted.

Dave in Canmore
Reply to  tty
November 21, 2014 4:18 pm

“GIA can only partly compensate for ice-loss since the rock is much denser than ice.”
Yes, that was my “back of the envelope calculation”

Geoff Sherrington
November 22, 2014 2:38 am

Doug Proctor,
You are suggesting a disconformity.
If this was angular, what might be some consequences for ice core dating and interpretation?
Geoff, a geochemist retired.

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