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Showing posts from July, 2017

Go with the flow

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These days, when we think of glaciers, we think of alpine glaciers. They're relatively small, and they occur only in the mountains. By definition, a glacier must flow, so a stagnant piece of ice is just ice, not a glacier. In alpine areas, glaciers flow for a couple of reasons, and the slope of the mountain is only part of the reason.

Ice is a solid, but under enough stress, it acts "plastic," which means that under enough stress, it can deform, or flow, without fracturing or breaking. If you hit an ice cube with a hammer, it will break into a million tiny pieces, but with the right amount of stress, applied over time rather than suddenly, the ice will deform, instead of shatter. It's similar to silly putty; if you pull silly putty apart quickly, it will snap, but if you pull it slowly, the putty stretches. If you’re unfamiliar with silly putty, check out the first 30 or so seconds of this video to see how it stretches and breaks.

Alpine glaciers flow downhill partiall…