Essay: Melting rock (decompression, volatiles, heat transfer)

The first method of melting rock is decompression. Decompression is when tectonic plates shift apart, creating a space in between. Hot rock then rises under these plates to fill the space. Then the rock rises and the pressure on the rock decreases and causes the rock to melt. The tectonic environment occurs in hot spots as well as rift zones. The second method of melting rock is volatiles. Water and carbon dioxide are both volatiles, and when introduced with other elements such as hot rock it cause the bonds to break. Once water is introduced to the hot rock, and will cause the rock to melt at lower temperatures, which will produce molten magma. The tectonic environment occurs along volcanic arcs bordering oceanic trenches. The third method of melting rock is heat transfer. When the hot magma rises past solid rock, it is often hot enough to melt the rock when they come into contact. The tectonic environment occurs partially in continental rifts.Five different hazards associated with volcanic eruptions are threat of flows, threat of falling ash and lapilli, threat of ash in the air, threat of the blast, and threat of landslides and lahars. The flow of lava destroys anything in its path whether it is cars, trees, houses and etc. The ash of the eruption contains toxic chemicals can poison the water, soil and it is bad for people to inhale. The blast of the eruption can be like a bomb going off which can be catastrophic for everything close by. The landslides that are created by the volcano eruption can also be dangerous due to everything falling and flowing at such a fast speed. When the volcano goes The gas that is emitted from the volcano can lead to catastrophe. On page 159 of the text book, it says,“According to one estimate, volcanic eruptions in the last 2,000 years have caused about a quarter of a million deaths—much fewer than those caused by earthquakes, but nevertheless a sizable number.” The ash that is made from the eruption explosion can travel very far which can hurt civilization because of sunlight not reaching the ground or dramatic climate changes. Physical weathering is caused by the fluctuating affect the temperature has on the rocks, making the rocks to break apart. “Mechanical” weathering occurs in places such as in mountain regions and deserts. Frost Wedging is one of the types of physical weathering. This occurs when water goes into cracks, freezes and opens the joint, causing for the rock to eventually break apart. Exfoliation is the second type, this occurs when parallel cracks develop to the land because of erosion. Chemical weathering is when chemical reactions cause for the minerals to be destroyed when the rock comes in contact with water or air. Dissolution is when water or air comes through a rock and it slowly dissolves the minerals. Hydrolysis is when water mixes with the minerals and breaks them down to form other minerals. Soil is the upper layer of the earth undergoes three changes including the reaction with rainwater and the consisting of organic material such as clay and rock particles. The process starts as chemical and mechanical weathering create debris and ions into a solution. The second step is water or rain seeps into the ground and distributes the solution of debris and ions. It then reaches the zone of leaching which carries the materials further downward. Reaching the zone of accumulation. This is when new minerals come out of the water passing through leaving even finer minerals behind. Lastly, below the ground surface the minerals mix with organisms. Climate, Substrate composition, slope steepness, and wetness are at least four factors that control how thick the soil deposits become. The four sedimentary depositional environments are glacial environments, mountain-stream environments, alluvial-fan environment, and desert environments. Glacial environments are obviously located in the mountains where it is cold. When the ice melts from this sediment it creates a glacial till which contains clasts that are the size rang of clay to boulders size. In Mountain stream environment, has downward slopes that stream the water down that cause for it to carry large clasts. The sediment carries sand and mud further down stream. Alluvial-fan environments are where the fast moving stream come to a plain surface. Since the water slows down it creates deposition where the water does not move the sediment. Which creates layers of sand, mud, and clay. Desert environments is where there is not much soil and not many plants grow in deserts. In deserts, the wind is what picks the sand and dust and moves it around. This results in dunes and thick layers of sandstone. Increasing sediment transport distance causes the size of the sedimentary rocks to become smaller in size because the longer they are transported there is more opportunity to experience multiple impacts by falling from mountains, tussling through rivers, and different environmental/weather conditions. The changes in shape and the finer sorting occur mainly as the sedimentary rocks travel through rivers and streams because the water smoothens out the very angular and coarse rocks into round pebbles and the process of transportation sifts out the larger pieces of rocks while the smaller pieces continue to travel further until the sediment consists of clasts that are well-sorted. As the sediment transport distance increases further and further, the sediment can be turned into very fine particles such as shale or mudstone.