冰川移动由两个过程:1。内部变形2。基底滑动这个数字(为我的候选资格考试),举例说明两个过程后,如果我们一块冰在冰川:[![在这里输入图像描述][1]][1]基底滑动是当整个冰川幻灯片在一起,辅助润滑的冰川和地面之间的冰水。内部变形当冰川移动,但摩擦地面附近减缓冰川底部的进展。但重要的是要指出,冰川仍总是朝着同一方向(向下),由重力引起的。因此冰川总是提前,倾向于保持在一起。(当我们说一个冰川消退,这意味着前沿的位置消退,不是冰本身。在前线,当冰融化的速度比它取代了前进的运动。)上述两个过程,基底滑动是主要的一个大型南极冰川和冰流,但不能从事cold-based冰川(即冰川底部在哪里不高于熔点,因此冰川冻到床上)南极洲本身更常见。 The picture you are proposing of a glacier splitting in two is a very rare occurrence. Because glaciers are very [ductile][2] and have good cohesion, it can only happen in rare occasions on very steep mountain glaciers, where the driving stress and basal sliding can be strong enough to take a large fraction on the glacier and send it rushing downhill ([like in this event][3]). In Antarctica the glaciers are so big, and the terrain so flat that you can be sure that will never happen. Ice there will evolve more like a viscoelastic material - you can picture that by imagining how honey will move if you pour a jar of it over a table. When people talk about Antarctica splitting in two they mean don't mean that the land will move apart, nor that the glaciers themselves will move in different directions and fracture. Instead it is about the loss of the ice; as ice creeps to the edges of the continent and is lost as icebergs, the snowfall inside the continent is not enough to replenish the ice lost. Therefore, the ice sheet over the continent is thinning. The land of Antarctica (without any ice) is made up of two separate big landmasses (East and West Antarctica) and a multitude of islands. [![enter image description here][4]][4] As the ice sheet thins, at some point sea water will progress towards the large areas with bases currently below sea level, the ice start to float, and will eventually completely break up. If that were to happen, Antarctica would become split into two sub-continents, and the ice loss would generate a catastrophic sea level rise. [1]: https://i.stack.imgur.com/Nwovq.png [2]: https://en.wikipedia.org/wiki/Ductility_(Earth_science) [3]: https://visibleearth.nasa.gov/view.php?id=88953 [4]: https://i.stack.imgur.com/qQqsF.png
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