Topic:- The eruption of vulcanoes. The advantage of this topic is that you can make a very interesting experiment; with a few rudimentary substances you can create your own small volcano.
The Eruption of Volcanoes [Biology]
The Big Bang theory explains the origin of time, matter, and space around 13.8 billion years ago starting from the explosion in the ‘singularity', the state of unity of time, matter, space and the four fundamental forces (strong atomic force, weak atomic force, electromagnetic force and gravitation force). Our Sun, a second generation star, formed around 5 billion years ago in the side arm of the Milky-Way Galaxy. At the time of its formation from the solar nebula (the molecular cloud persisting around the Sun after it condensed from the Proto-Sun) around 4.55 billion years ago, the Earth was hot molten mass. The difference in the relative densities of the various elements mediated the stratification of the Earth while it was cooling down. The proportionally abundant heaviest metals sank deepest towards the center of the earth core, the lightest elements and their compounds floated on the surface while those of intermediate density settled in between the center (Earth's core) and the outermost surface. The core consists of an innermost iron sphere that persists in the solid state due to immense pressure from external components of the Earth mass, and a liquid iron-nickel alloy layer surrounding it externally. The inner core is externally surrounded by the mantle. It consists of molten silica rocks abundant in iron and magnesium. It has a temperature of around 40000C to 5000C (from core towards the surface) and is highly pressured due to the presence of outermost crust. The solidified surface externally surrounding the mantle is called crust. It generally consists of lighter elements and their oxides. While stratification during cooling of the Earth, the crust did not form one continuous layer of even thickness around the mantle.Instead, it partitioned into seven plates (also known as the Plate Tectonics or continental plates) floating on the inner molten mantle. The inter-tectonic surface constitutes around 70% of the crust in the form of massive water bodies like the oceans and seas. It is the contents of the mantle that escapes through the weakened Earth crust in the form of volcanoes.
The volcanic eruptions may occur when two continental plates pass over each other beyond their margins or spread apart. While making an imaginary depiction of the crust and the underlying mantle, consider a spherical ball, say, a football. The thickness of the football material depicts the uniform innermost layer of the crust that lies immediately above the mantle. Stick seven pieces of the thick cardboard (a few millimeters thick) on the outer surface of the football, they depict the Plates Tectonic. Now place a smaller golf ball at the inner center of the football, it depicts the core. The space between the core and the football's inner surface depicts the mantle. The deep grooves among the elevated cardboards (Plates) on the outer surface of the football depict the water bodies like the oceans and sea. Since the mantle is in contact with the inner heated core and extremely pressurized by the weight of the outer crust, it escapes through the crust whenever there's the weakening of the crustcovering it. It's like the escape of water filled inside the football through a pinhole punctured in it. While the Plates Tectonic arein constant and random motion, any two of them may pass over each other's margin. It causes the crust lose it integrity and the lava escapes through it causing volcanic eruptions. The mountain-shaped conical volcanos form the same way. The mouth of the volcano through which the lava and other volcanic materials escape into the environment is called a volcanic vent (similar to the pinhole on the surface of the football). The mountain-like conical part of the volcano is the solidified lava around the vent. A volcanic eruption may also occur when the Plates move apart from each other while floating on the molten magma. As a result, the lava escapes from the ‘torn apart' crust in the form of volcanoes.
The volcanic eruption may release water vapor, gases (carbon dioxide, carbon monoxide, sulphur dioxide, hydrogen chloride, etc.), ashes and even molten lava. The immense heat and molten rocks flowing on the Earth's surface eradicates all life forms coming in its contact. The volcanic eruption of the Mount Vesuvius, Italy, AD 79, virtually covered the cities Herculaneum and Pompeii with lava burying around 10000 people underneath. The dense clouds of ashes and toxic gases (CO2, CO, SO2) may also exaggerate the disaster by poisoning the normal respiratory air to far greater distances. The death tolls due to thevolcanic eruption in the Mount Tambora, Indonesia, 1816, reached around a hundred thousand. The mankind has witnessed several other volcanic eruptions causing massive loss of life forms and the ecosystems. Simultaneously with claiming human lives, the volcanic eruptions also destroy the floras and faunas of the ecosystem, crops, architectures, and the water sources in close proximity. Moreover, the toxic gaseous in it may cause respiratory problems to animal forms even at distant places and adversely affect the vegetative and microbial community, too.
However, the volcanic eruptions also enrich the ecosystem with vital minerals. The volcanic ashes are rich in potassium, sodium, calcium and traces elements like cobalt, copper, iron, nickel, and manganese, etc. The mineral deposition on Earth crust may favor the growth of some organisms over others. The distribution of the volcanic gases throughout the biome through the biogeochemical cycles may also enrich the biodiversity of thevarious ecosystem in close proximity and distant. The barren surface of solidified lava is usually first inhabited by lichens, the pioneer species on a newly exposed Earth surface. Through primary, secondary and tertiary succession, the vegetation is gradually replaced by relatively larger and prominent species. Indue course of time, the barren surface may also develop into an ecosystem with enriched biodiversity. Though always disastrous to the mankind, the volcanic eruptions may be of great ecological significance by eliminating and modifying the pre-established ecosystems and creating a platform for the establishment of thenew ecosystem.
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