Explain the formation of coal and oil. Answer the following questions in detail.
Answers
coal is prepared in mines and oil is prepared by cultivate the crops
"Formation of Coal:
Large quantities of coal was formed during the Carboniferous period. At that time, the oxygen content in the atmosphere was 35% and a large number of trees with barks were found on the Earth. Saprophytes had not evolved yet and thus, these trees were buried inside in the Earth. The high oxygen content lead to swampy conditions which meant that multiple layers were built upon these buried trees. High pressure and temperature led to these trees getting fossilized into different types of coal.
The precursor is called peat. When peat is subjected to high temperature and pressure, it gets transformed into lignite. Over time, lignite becomes sub-bituminous coal which then is converted into bituminous coal, a type of dense sedimentary rock. Bituminous coal ultimately becomes anthracite coal which is glassy and is considered the most superior form of coal.
Formation of Oil:
Large quantities of oil was formed during the Mesozoic era. Dead micro organisms such as plankton, algae and bacteria got deposited on the shallow ocean beds. These dead organic matter got mixed with the inorganic silt deposits and were trapped in anoxic environments. This trapping led to these matter getting lithified and thus forming organic shale. With increase in pressure and temperature, the organic shale becomes waxy and gets converted to kerogen which eventually becomes oil.
Since the density of oil is lesser than that of water, it displaces water and rises through the rock pores to the surface. If an impermeable layer exists on the rocks, then the oil becomes trapped beneath it.
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