If you take a look at this picture you can see what looks like almost nicely cut out 'roads' between the mountains.
What forces are responsible for this?
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$\begingroup$ What do you mean by a "road like pattern"? $\endgroup$ – gerrit♦ Jul 12 '17 at 23:01
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It's a glacier, it this case the Baltoro Glacier in Karakoram, Pakistan. The road-like pattern is formed as the glacier slowly flows towards lower altitude from a nearby ice-cap or accumulation zone. Rocks and dirt is transported both within the ice and on the surface.
With a closer look, the surface is rarely smooth, but often deep trenches, cravasses, and meltwater channels are formed as the glacier moves. On a human timescale, the glaciers crawl slowly, but from a geological perspective they are fast.
Closeup of a glacier with crevasses. (By Roylindman at en.wikipedia, CC BY-SA 3.0)
Under the glacier, a U-shaped valley is formed as the glacier erode the bedrock. Depending on the dynamics of the glacier and the erosion, the glacier might also appear clean, without sediment on the surface.
Large glacier without sediments, but also with a very uneven surface due to the movements of the glacier (Wilkes Land).
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2$\begingroup$ Thanks for the edit @Etienne Godin . A good clarification for a too short answer. $\endgroup$ – Tactopoda Jul 12 '17 at 23:59
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2$\begingroup$ to the point answer for a simple question! felt like just adding the origin of the forces driving the glaciers to your well rounded explanation $\endgroup$ – fre0n Jul 13 '17 at 1:18
