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Sodium_ wrote:This is my first year doing dynamic planet, and my partner and I winged it at regionals. We got lucky, and did pretty good, but I would want to risk it for state. What would be some good links, and some stuff to study that's not on the wiki or soinc links? thanks so much! And I saw earlier on this forum that someone used a textbook- if anyone knows any good textbooks, I would really appreciate it. Thanks so much!

jameswei wrote:Hey I'm stuck on things to put on my cheat sheet. We're going to state soon and we finished 3 of the 4 pages. Does anyone have any idea on what to put? i have pictures, vocabulary, and history.

PacificGoldenPlover wrote:ceg7654, this is how I understand it works:

Remember that a glacier does not start out in motion. It starts out technically as an ice field moving at 0 m/h- the bergschrund divides this from the rest of the zone of accumulation. Deeper ice means a higher surface-velocity. As ice accumulates throughout the zone of accumulation, the glacier will get progressively faster, until peak at the equilibrium line.

Then, as the ice moves through the ablation zone, it slows down, because the glacier is losing its depth, and in addition topographic irregularities become harder to "navigate" since there is no longer the pressure present to either go around or crush them. So the glacier slows down.

I'm pretty sure that's how it works, though my two glacier books don't say why specifically it happens.

More important to them is the evidence that in the zone of accumulation there is extensional flow, illustrated by snow-covered crevasses, indicating the front of the crevasse is moving faster than the back of the crevasse. Past the equilibrium line, these crevasses gradually close due to the opposite compressional flow.

EDIT: Another reason it may flow faster at the equilibrium line than in the zone of accumulation is because there is more basal water flow present.