Geology And Geophysics

Volcanoes on Earth



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In spite of what we perceive on a daily basis, our small and seemingly docile planet is actually a gnashing, grinding sphere of constant, mind-boggling forces. Earthquakes shake our planet to the core, causing untold damage to cities and towns alike. Hurricanes tear across our land, uprooting trees, houses, and even people in a drenching torrent of chaos. Tsunamis crash onto the shore, erasing all evidence of civilization in its wake as if it were a mere sand castle.

However, in view of all the most powerful phenomena of our planet, the fury of an erupting volcano is arguably the most terrifying and awe-inspiring. Just at the mere mention of volcanoes, one immediately conjures to mind images of billowing clouds of ash, gas and steam bursting from the crater of a tall, brooding mountain. Destructive rivers of spewing lava pour from the opening, stopping at nothing- not even the surrounding innocent towns- until even the trees of the area are transformed into burnt match sticks.

One of the most memorable and violent explosions recorded was the 1883 eruption of Krakatoa in Indonesia. To put it in perspective, the eruption of Krakatoa makes the more memorable Mt. St. Helens pale in comparison. An estimated 36,000 people died in the huge blast, which emitted the loudest sound in recorded history. In fact, the blast was heard quite distinctly all the way in Australia- 3,000 kilometers away (Attenborough 26)!

Despite all of this seemingly chaotic power and fury, volcanoes have played an important role in the development of our planet. For instance, they are the great sculptors of our land. The reason for this is because volcanism has occurred virtually everywhere on our planet. In fact, if you dig a hole deep enough, chances are, no matter where you are, you will hit some kind of volcanic rock. This is because nearly 80% of the earth's crust is of volcanic origin (Lee 56). Much of the surface of our earth was in fact shaped by these very internal forces that cause volcanoes to spew. The reason why is due to the forces that take place within the crust. They can be broken down into three categories: movement of bodies of solid rock, movement of hot liquid materials, and transformation of rock due to high pressure and heat far below the surface (Flint 10).

Recently, scientists have been speculating that volcanoes have even played a more crucial role in the biological development of our planet as well. One geologist, Sigurdsson Haldur, speculates that steam from primitive volcanoes "eventually condensed into oceans" (Lee56). Haldur then goes on to explain how blue-green algae took the carbon dioxide from the atmosphere, and, by using energy from the sun, turned it into oxygen. In fact some of the most primitive forms of these types of organisms many have appeared on our planet in the form of bacteria some 300 million years ago (Attenborough 39).

So as we can clearly see, the forces at work within our planet have had several functions in the overall systemic development of our living planet. It is amazing to realize that volcanoes and volcanic activity have not only built mountains, islands, and oceanic rifts, but that they may have actually aided in the evolution of life on our planet.

References

Attenborough, David. The living planet. Boston: Little Brown and Company, 1984

Flint, Robert F. The earth and its history. New York: W. W. Norton & Company Inc, 1973

Lee, Chris E. Our awesome earth-its mysteries and its splendors. Washington D.C.:

The National Geographic Society, 1986

Tarbuck, Edward J. And Lutgens, Frederick K. Earth science ninth edition. New Jersey

Prentice Hall, 2000

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