英国地理essay代写 冰山犁痕

Keywords:英国地理essay代写 冰山犁痕

在B区，整个区域都能看到和识别冰山犁痕。这些犁痕的形式可以有很大的不同，取决于沉积物的类型、冰山龙骨的形状(通常是v形)和冰山的运动(Shakesby, 1986)。坑中出现的这些犁痕表明一段时间内冰的流动较慢，因为沉积物被允许积累，然后冰山在冰后退时形成了洼地。这些洼地可以被描述成更多的v型，这提供了它们是由冰山(而不是其他大型物质)形成的证据，如图3.6的剖面图所示。Graham等人(2009)指出冰山犁痕记录了冰架进化的最新阶段，随后在冰消退时形成。这些犁痕表明，经过一段时间的快速流动(C区)后，冰的消退速度变慢，从而形成了这些冰下地貌。他们强调了冰流的重要性，特别是它们流动的速度，在构建南极洲周围海床地貌的过程中。总而言之，过去的冰流对南极洲周围的松岛海槽海床上形成的地貌产生了巨大的影响。产生的一系列特征显示了冰流经过的不同状态，GMZ和冰山犁痕显示了停滞/慢流的时期，而MSGLs显示了快流的时期。通过Dowdeswell等人(2008)的南极冰流后退模型，我们可以得出这样的结论:深坑区域最符合冰流后退的幕式特征，快流速和慢流速交替出现，形成叠加的接地带楔。这些发现现在可以用来帮助预测未来的流量和随后的地形，因为冰继续退缩，并以更快的速度，作为人类活动增加的结果。
英国地理essay代写 冰山犁痕
In Area B iceberg ploughmarks could be seen and identified across the entire Area. The form of these ploughmarks can vary significantly and depend on the type of sediment, the shape of the iceberg keel (usually V-shaped) and the motion of the iceberg (Shakesby, 1986). The presence of these ploughmarks in the PIT indicates a period of slower ice flow, as sediment has been allowed to accumulate, and then the icebergs have formed depressions as the ice retreated. These depressions can be characterised as more V-shaped, providing evidence they were formed from icebergs (not other large forms of materials), as seen in the profile graph of Fig. 3.6. Graham et al (2009) states that iceberg ploughmarks record the latest phase of shelf evolution and were subsequently formed when the ice retreated. These ploughmarks are evidence that after a period of fast flow (Area C) the ice retreat then slowed, allowing these subglacial landforms to be formed. They highlight the significance of ice streams and in particular the speed in which they flow, in constructing the geomorphology of the sea floor surrounding the Antarctica.In conclusion, past ice streams have had a huge impact on the features formed on the sea floor in the Pine Island Trough around the Antarctica. The range of features produced demonstrates the different states of flow the ice streams went through, with the GMZ and iceberg ploughmarks showing periods of stagnation/slow flow and the MSGLs showing periods of fast flow. Looking at Dowdeswell et al. (2008) model of Antarctic ice-stream retreat we can conclude that the PIT area conforms most to the episodic retreat with periods of fast and slow flow causing superimposed grounding zone wedges to be formed. These findings can now be used to help predict future flow rate and subsequent landforms as the ice continues to retreat, and at a faster pace, as a result of increased anthropogenic activity.