Despite our tendency to consider Earth as static, it is actually a dynamic and ever-changing planet. Wind, water, and ice erode and shape the land. Volcanic activity and earthquakes alter the landscape in a dramatic and often violent manner. And on a much longer timescale, the movement of earth’s plates slowly reconfigures oceans and continents. Each one of these processes plays a role in the Arctic and Antarctica.
Wind, water, and ice are the three agents of erosion, or the carrying away of rock, sediment, and soil. Erosion is distinguished from weathering — the physical or chemical breakdown of the minerals in rock. However, weathering and erosion can happen simultaneously. Erosion is a natural process, though it is often increased by humans’ use of the land. Deforestation, overgrazing, construction, and road building often expose soil and sediments and lead to increased erosion. Excessive erosion leads to loss of soil, ecosystem damage, and a buildup of sediments in water sources. Building terraces and planting trees can help reduce erosion.
In the Arctic and sub-Arctic, glacial erosion has shaped much of the landscape. Glaciers primarily erode through plucking and abrasion. Plucking occurs as a glacier flows over bedrock, softening and lifting blocks of rock that are brought into the ice. The intense pressure at the base of the glacier causes some of the ice to melt, forming a thin layer of subglacial water. This water flows into cracks in the bedrock. As the water refreezes, the ice acts as a lever loosening the rock by lifting it. The fractured rock is thus incorporated into the glacier’s load and is carried along as the glacier slowly moves.
Abrasion happens when the glacier’s ice and rock fragments act as sandpaper, crushing the rock into finely grained rock flour and smoothing the rock below. Melt water streams of many glaciers are grayish in color due to high amounts of rock flour. Glacial erosion is evident through the U-shaped valleys and fjords that are located throughout the Arctic and sub-Arctic regions. Glacial moraines are formed as a glacier recedes, leaving behind large piles of rock, gravel, and even boulders. Moraines may form at the foot (terminal moraine) or sides (lateral moraine) of the glacier or in the middle of two merging glaciers (medial moraine).
In Antarctica, kata batic winds play a large role in erosion. This type of wind occurs when high-density cold air builds up at high elevations (on the ice sheets, for example) and moves downhill under the force of gravity. Katabatic winds in Antarctica and Greenland are intensely cold and fast, often reaching hurricane speed.
A volcano is simply an area where magma, or molten rock, from the earth’s mantle reaches the earth’s surface, becoming lava. Most volcanoes occur at plate boundaries, where two plates are moving away (diverging) or together (converging). A few volcanoes like the Hawaiian Islands form from a hot spot, or a weak spot in earth’s crust, where magma forces its way to the surface.
Volcanic eruptions may be explosive (violent) or effusive (passive), depending on the lava chemistry (amounts of silica and dissolved gases). Silica is a mineral found in nature as sand or quartz. High levels of silica mean very viscous (thick) lava, and low levels mean more fluid lava. Dissolved gases build up inside the volcano, much like a can of soda or other carbonated beverage. The higher the level of gas, the more pressure that builds – and the more violent an explosion. The combination of silica and dissolved gas levels determines the type of eruption and shape of the volcano. Volcanoes are classified into four types, based on their lava chemistry and shape.
In conclusion these are all many reasons why the earths structure changes over time.
Hope this helps ya!! I have done an essay on the same thing like a few weeks ago and kept it but i switched up some words.
