Dynamic Planet B/C

[PacificGoldenPlover]

Are you familiar with http://nsidc.org/ yet?

[DynamicPlanet14]

What resources did you guys use to learn how to read USGS maps? I am struggling with the representative activities. Thanks!

[zyzzyva980]

From a couple of years in Road Scholar, the best way to learn how to read maps is to read maps.

As unhelpful as that sounds, it works- just take some time to pore over a few maps and understand what every single funny marking means. The USGS website has lots of helpful aids as well.

[EastStroudsburg13]

It might be fun to try reading a map of the area that you live in. That way you might be able to recognize certain landmarks on the graph, which will help you remember them in the future. Personally, I like reading maps regardless, but I'm a little insane, so I recognize that it might not be as easy for someone else.

[roadscholar11]

Does anyone have any ways to study pictures of glaciers? The picture ID sections sometimes trip me up.

[mej710]

Does anyone have any ways to study pictures of glaciers? The picture ID sections sometimes trip me up.

One thing that helped me identify glaciers and other features on a topographic map was putting some examples on my note sheets to reference during the event. Or maybe you can look for a few different pictures of the same glacier on google images or something and look for similarities between the pictures so you arent just familiar with what the glacier looks like in one picture and you would be able to see what the most common features are for each type of glacier.

[ceg7654]

For the Mesa Robles test, one of the questions was about where glaciers move the fastest. The correct answer was the equilibrium line. Can PacificGoldenPlover or anyone who understands, really, explain to me why this is? I understand why got it wrong but why do glaciers move fastest at the equilibrium line?

[PacificGoldenPlover]

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.

[colorado mtn science]

For the Mesa Robles test, one of the questions was about where glaciers move the fastest. The correct answer was the equilibrium line. Can PacificGoldenPlover or anyone who understands, really, explain to me why this is? I understand why got it wrong but why do glaciers move fastest at the equilibrium line?

Although Pacific Golden Plover's answer made sense, technically the fastest part of the glacier is down the middle at the surface (although the equilibrium line is a good answer for what part along the length of a glacier the ice flows fastest)

[PacificGoldenPlover]

While it is true that glaciers move faster in the middle at the surface than at the sides or base, I made it a multiple choice question. Those others were not options on the test.