Geologists Surprised to Find Glaciers

[miker]

Interesting article, less ice for some of you, but maybe that means more rock for me

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Geologists Surprised to Find Glaciers

By JOSEPH B. VERRENGIA, AP Science Writer

ROCKY MOUNTAIN NATIONAL PARK, Colo. (AP) - Geologists exploring the rugged Continental Divide say they discovered more than 100 additional glaciers here in a single summer, a surprising find since glaciers around the world are shrinking in warmer temperatures.

The results dramatically change the map of one of the nation's oldest and best-known national parks, along with the knowledge of weather and water cycles at high elevations.

Previously, officials believed the park 60 miles northwest of Denver included 20 permanent ice and snow features, including six named glaciers.

The new survey by geologist Jonathan Achuff shows there are as many as 120 features. Most are located in cold, north-facing pockets on the east side of the Divide at elevations above 12,000 feet.

Most of the newly discovered glaciers are covered with rocky debris; continuous freezing and thawing splinters the brittle granite that forms some of the park's majestic peaks. Park officials say comparisons with historical photos suggest that at least some of the glaciers are expanding.

Glaciers are barometers of climate change, and researchers said the survey results here contradict global warming trends.

In Antarctica, the Pine Island Glacier thinned by 36 feet in eight years; the rate of ice-thinning is 10 times greater than the rate of snowfall there.

In Africa, the famous white mantle of Mount Kilimanjaro has shrunk by 82 percent since 1912. A survey by Ohio State researcher Lonnie G. Thompson predicts the equator-straddling glacier will vanish entirely by 2015. Already, some rivers in Tanzania have dried up as a result, he said.

Similar icy retreats have been measured in the Andes of Peru and the Himalayas of Tibet. Aerial photos over the past three decades show the number of named glaciers in Montana's Glacier National Park has dropped from 83 to fewer than 65.

Perhaps the only major glacial system that is increasing in size today is in Norway. Coastal glaciers are more complicated, and some global warming models predict increased snowfall there as precipitation patterns change.

In Colorado, park officials said subtle climate changes may be helping the formation of glaciers or at least reducing their retreat.

The Divide already funnels snow from the West up and over ridges, where it settles in eastern basins just below the tallest peaks.

Also, expanding development near Denver is sending hot air that helps to form additional cloud cover over the mountains in the summer. While precipitation hasn't changed much, temperatures have been slightly cooler in the past several years.

``We're not running quite in synch with global warming here,'' park spokeswoman Judy Visty said.

Achuff and others are preparing expanded studies that would begin next summer, including the possibility of drilling core samples to the bottom of large ice features, using satellites to measure the glaciers' movements and seismic testing to determine how much ice and rock the features contain.

Perhaps the most significant of the newly discovered glaciers is located beneath a boulder field near the 14,255-foot summit of Long's Peak, one of the West's most popular climbs. The glacier, it turns out, has been skirted by thousands of visitors annually.

Previously, some geologists speculated that the boulder field was a ``rock glacier'' - a catchall term for thick mixtures of debris and ice. But the granite may actually cover up a thick ice slab, insulating it from the sun.

``There could be a large chunk of ice under there, perhaps several hundred feet thick and a mile long,'' Visty said.

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On the Net:

Park: http://www.nps.gov/romo

Geological Society of America: http://www.geosociety.org

 

[David_Parker]

It sounds like these guys are confusing permanent snow fields with glaciers. However I'm not a geologist so I don't know the technical difference. I do know that when I lived in Utah that the lowest (latitude) permanent snow in the lower 48 was supposedly on Mt Timpenogos out of Heber City. Some one here should post and explain the difference between permanent snow fields and glaciers. I'm suspect that Rocky Mt. Park suddenly has 100 new "glaciers".

If I were to take a stab at it, I'd say a glacier actually creeps down the mountain, regardless if the toe is advancing or receding. A permanent snow field just sits there.

Also, it could be argued that global warming actually can cause more moisture to evaporate into the atmosphere and that the additional moisture must fall somewhere, most likely at the extremities of the planet...the higher elevations and the northern and southern latitudes. Therefore global warming CAN cause increased snowfall and glaciers to advance!

[Rodchester]

Snowfield = an area/patch/field of snow that does not melt out on a yearly/seasonal basis. Many snow fields are glacial remants...such as the Muir snowfield on Rainier. That is why you will have crevasses on SOME snowfields. But not all snowfields were once glaciers.

Glacier = A dynamic section of ice built up to the point that its own weight causes it to move. Usually it reaches terminal depth at 100 feet of compacted thickness. It thenn moves toward the path of least resistence.

Belive it or not it is possible to move straight down...yes down. When the glacier builds up an incredible amount of weight though ice thickness (usually around 1000 feet thick...no there are none on earth like this today) it begins to compress the earth's crust and push straight down.

The simple fact of the matter is that there are no easy answers to glaciers receeding and advancing. Many have huge advances based on the same principal as hydroplaning. The water melt builds up and the glacier make big advances quickly by surfing, so to speak. Sometimes the build up can be such that a glacier should be moving fast...and it is not. It could be held up by some feature under the glacier that is providing more than normal resistence to the glaciers' movement. Until the glacier either changes directions or eventually defeats the resisting feature, the glacier may not move.

There are soo many vairables and we just know so little about them.

Dry Glaciers = When a glacier moves it picks up all kinds of rock and dirt from the peaks and walls around it. As the glacier pushes this material towrds its snout, or terminous, the ice begins to melt away. This leaves what appears to be a huge boulder field...which it is....but is it a huge bouldr field on top of a still moving and active glacier. This are actually quite common in South America. I have crossed a few.

One question is: At what point does a receeding glacier become a snow field?

No I am not a glaciologist and don't claim to be be one. But I have read about and observed glaciers for more than a few years.

Anayway..that is my 50 cents.

[offwidthclimber]

Thanks for the post and links mikereddig.

I watched a program the other day about Glacier National Park. Some of the scientists there studying the glaciers have predicted that at this rate, they may all be gone in about 30 years.

Cheers,

Micah

[Dru]

heh heh norway is not only place in the world glaciers are increasing. also on n. bc coast.

more warming = more evaporation from oceans = more precip on BC coast = more snow on icefields (already snows 10 months out of the year up there) = bigger glaciers.

when your glaciers are all gone we will let you come up and play on ours if you ask nice.

[Beck]

Isn't the mer de glace up in Greenland 1000 feet thick, David?

[Dru]

There are sections that are 3 km thick! And thicker ones in Antarctica... thats where they get those climate core samples.

[Alpine_Tom]

Another interesting glacier factoid.

The upper East Rongbuk (on Everest) is a particularly interesting place, because it is so slow moving. At the research site, liquid water does not exist at the glacier bed, unlike virtually all other non-polar glaciers in the world. Here, at over 20,000 feet in elevation, the glacier is frozen to the rocks below and moves by deformation, not sliding. They are doing oxygen isotope studies on the ice, which is thousands of years old at great depths.

[Walter_Burt]

Last I knew a number of the large glaciers in AK and the Yukon were pushing 1,000 feet+ The Ruth Gl. in particular is many thousand feet thick making the Ruth Gorge one of the deepest canyons in the world, if you take the ice out.

[Dru]

those deepest canyons stats are kinda tricky. measuring peak to valley bottom is a lot different than rim to bottom in something like the grand canyon. but if you do use that peak to canyon figure there is a canyon in the himalaya that is 20 000 feet deep, by daulaghiri. the ruth gorge is 5000' deep and would be 8000 if you took out the ice.

lets not turn this thread into geological trivia though because it will eventually come down to the which is bigger everest or mauna kea idea. yawn.

[Fairweather]

I know some about this subject. Actually there is a place right here in WA where the ice is over 1000 ft thick...just down from the base of the Blue Glacier Icefalls on Mount Olympus. Another factoid: the largest glacier "by volume" on Rainier...The Carbon. It is over 500' thick in places.

Someone spoke of "dry glaciers". I was in the Wrangell Mtns two years ago near Mount Blackburn. Even with all of the huge "active" glaciers around I noticed at least a dozen rock glaciers around and above the Root/Kennicott flow. I guess miners actually bored through a few of them to get at the mountainsides which were laden with (75% pure) copper ore.

[max]

Can anyone give a good, thurough description of what a rock glacier is? Is it a rockslide that is undergoing mass movement? Ice covered with rock? 1/2 scotch, 1/4 ice, 1/4 lemon?

[mattp]

A rock glacier is a heap of rock that is moving downhill much the same as an ice glacier, forming moraines and other glacial features. They contain some ice in addition to the rock, but rock debris is predominant. Some "rock glaciers" are remnants of former ice glaciers, while others have formed without prior glacial ice. They typically form in areas with a colder, drier climate, but Washington has some on the east side of the Cascades -- as on Oval Peak.

 

[max]

ok, so is there a interface of sliding and not sliding, or is is a continum of not sliding, sliding just a bit, sliding a little more, and sliding? (What I'm getting at here is the interface bewteen rock and ice where on surface is sliding on the other...) If it is the second case (a continum of movement...) how do geologist determine a mas sod rocks is arock glacier, and not just a pile of rocks roling down the hill?

[mattp]

I think the determination is made with the aid of 1/2 scotch, 1/4 ice, 1/4 lemon.