生物学essay高分范文_高分代写技巧

发布时间：2020-06-06 热度：

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Permian killer

The Permian, a golden age with biodiversity 250 million years ago, suffered a catastrophic event that approximately wiped out 95% of species on the planet. Compared with the demise of dinosaurs, this one happened earlier could be the biggest mass extinction in the world. To explore the actual reasons leading to this particularly disastrous extinction, several geologists and scientists contributed their efforts to it. Although researchers knew few details about that event, many methodologies and practices were applied to this situation in order to prove that whether their theories are practical or not.

In the first place, attentions were paid to a sub-Arctic wilderness, a region of Siberian known as the Traps, in the early 1990s. Dated back to 250 million years ago, this place was a blazing torrent of lava, the flood of lava lasted for millions of years. Vincent Courtillon had his theory that there was a possibility that the disruption of cooling followed by massive lava eruption which potentially had the ability to cause a temperature rise of 5 degrees could result in such a large-scale mass extinction like this. Whereas the geologist Peter Ward in the US disagrees with that theory, he claimed that an increase of 10 degrees in temperature could probably trigger a mass extinction like this scale through analyzing the data collected in the Siberian Traps, but a mere rise of 5 degrees could hardly wipe out 95% of all life forms, which means that the “flood basalt eruption” was not extremely deadly. Therefore, Vincent’s previous theory seems not to be that convincing.

Until 1998, Michael Rampine in the US decided to evaluate the timescale of the Permian mass extinction to speculate if it was an “instantaneous killer” or something slower. He went to the Alps, which is one of the only places where there are Permian fossils. By analyzing rock sedimentation rates in Alps, the conclusion that the Permian mass extinction merely stalked the earth for less than 10000 years was made. From a geological perspective, this could be allocated into “instantaneous killer”. One thing occurred to him that a meteorite could possibly cause this. Just like the end of dinosaurs, one 50% bigger meteorite would be capable of triggering such a severe environmental change overnight. However, the lack of evidence could not prove that there was a meteorite strike because they could not find crater, the trace of meteorite. Fortunately, the London scientist, Adrian Jones, used his experiment to demonstrate that if the meteorite was massive enough, it not only caused a wider, shallower crater, but also melted the Earth’s crust. Eventually, the lava would be released. As a result, lava would fill the crater and flow beyond the edges of the crater as well as the original crater structure. However, this seemed to be too simple to be believed.