Encyclopedia of Science

[george99]

I don't understand the explanations by glacier scientists.

I've read articles that explain formation of glaciers; they say the increasing mass causes them to move down by gravity.
Place an ice cube at the top inside of a large bowl; it slides down to the bottom. It will not slide down if it's frozen to the top ridge.
I assume the mass of a glacier moving down a valley is greater than any physical attraction at the top part. In other words, it's a moving object.

I've seen diagrams showing the extension of white stuff (glaciers etc.) from the Arctic southward to the Great Lakes area in North America.
I can understand how lower temperatures could cause additional white stuff. But that doesn't make it move; there's just more of it!

"Going south" (from the North Pole) is not the same as going down a valley.

Shed some light on this?

[treelover]

Glaciers just happen to be ice. That they are ice isnt really important.
To be politically correct, 'faeces' rolls downhill. If instead of ice the material was 'earth' it could still go downhill.

The Key to this movement is lubrication.

Dry earth is mostly stable, wet it and you can get a mud slide. The mud is slippier ( and heavier ) than the dry earth.
With snow falling on snow, the upper snow presses down on the lower snow, compacting it into ice, the ice at the bottom and sides of the glacier is under massive pressure from the ice and snow above it vertically and from up the valley horizontally. Ice under pressure melts... into water water is the lubricant here and where water is trapped between the ice and the rock it forms a water slide. put a large sheet of plastic on a lawn wet it, take a run up to it and jump onto it and you'll slide forever. Try it without the water first. if you are lucky, your feet will grip the plastic and you will gather plastic as you slide across the grass - if your not, you'll stick to the plastic, the plastic will stick to the ground and your head will overtake your feet and you'll fall flat on your face - ouch!!

Compriz?

BoB

[george99]

"put a large sheet of plastic on a lawn wet it, take a run up to it and jump onto it and you'll slide forever."

No I won't slide forever.
On a level lawn, I'll stop not far from where I jump on the plastic.
If the lawn goes downward from my entry point, I'll go farther.
If the lawn goes upward, I definitely will stop.

I don't understand how a glacier can move over hills.

Has this been demonstrated?

[cmoralez]

Glaciers do not move over hills. They move through valleys and form fjords to move through areas in Norway and Alaska. You can actually see the movement and changes of glaciers from one year or season to the next. For example, one large glacier is moving closer and closer to a community in Alaska that believes it will eventually overcome them and wipe out the community. As they "calve" -- glacial ice breaks away and falls into the body of water in front of it -- there are openings that are created for addtl glacial ice to move. They also have water moving between the underneath of the glacier and the earth's surface, which allows them to slowly move forward. People have explored the tunnels and cracks that form and in some cases been able to observe the point where the glacier meets the water and earth's surface.

[george99]

If we liken a glacier to a large sled...
The sled is formed at the top of a hill.
Being disconnected at the top, it moves down the hill.
As it moves down the hill, it may get larger.
But when it gets to the bottom of the hill, it stops.

What I don't understand are the claims that glaciers move from the North to South (in northern hemisphere), across all terrains.

Isn't that what many claim?