History of the Geology of Earth - Research Paper Example

Introduction Theoretically, the earth was formed about 4.6 million years ago when the sun was formed. In its initial formation stage, the earth was a ball of molten magma that revolved violently around the newly formed star, the sun, and it collided with many other smaller rocks and debris from other planets in the solar system. The collisions and the gravitational pull balance slowed down the violent revolution and the earth’s surface began to cool down. Water vapor formed clouds and the earth flooded with water that formed the oceans and the dry parts later drifted apart and formed the continents. The earth has undergone very many physical changes on its geological features since its formation. The earth’s continents have been drifting apart for millions of years since their formation. 760 million years ago, during the initial stages of drifting, the earth’s continents had combined to form the Rodinia super continent. Around 600 million years ago, after rodinia broke apart, the continents drifted and formed Pannotia. Pannotia broke apart and the continents later formed Pangaea. Pangaea broke apart and the continents started drifting away from each other, 180 million years ago. The history of the geology of the earth is divided into chronological eras during which the earth had some outstanding characteristics and major geological events took place. This paper addresses the history of the geology of the earth. The Precambrian eon The Precambrian is the era began at the time of the formation of the earth and lasted till around 570 years ago. This period of time makes up to about 90% of the earth’s geology history. In the initial period of the Precambrian, the earth was cooling down and it formed a crust that made its surface. The rocks that were formed were mainly volcanic and igneous intrusions rocks which were spread all over the surface of the crust. The Precambrian had three long eras, the hadean, Archean and the Proterozoic. The Hadean lasted almost 700 million years after the earth’s formation. During this period, the earth cooled down and there was the formation of the earth’s surface which was mainly composed of volcanic belts. The temperature of the earth’s surface was still very hot but it was gradually cooling down due to the reduction in collisions with huge rocks in the earth’s orbit. It is also during this period that the earth’s moon was formed. Archean is the era that followed. It lasted from 3900 to 2500 million years ago. The earth experienced tectonic processes that formed sedimentary basins on its surface (Stanley 55). The rocks dated from this period reveal that there was simple life; bacteria and algae fossils were present on the rocks. The proterozoic period, 2500 to 570 million years ago, was characterized by the formation of vast rifts on the earth’s crust. The rifts were filled with volcanic rocks as well as the sedimentary rocks from the sedimentary basins (Sasso 59). This period also saw the formation of seas in which a lot of iron minerals were formed. There was early life in the seas and the amounts of oxygen kept increasing in the atmosphere. In the proterozoic eon, the Rodinia super continent drifted apart and later the Pannotia super continent was formed. Glaciers also started forming on the earth’s surface in the eon. The Phanerozoic Eon This is the eon in which the earth is currently in. It wraps the geology history of the earth from 550 years ago to date. After the breaking of the Pannotia super continent, the continents drifted and recombined to for the Pangaea. Pangaea then broke into the current continents. The continents have been constantly drifting apart. The phanerozoic eon is also categorized into three eras, the Paleozoic, Mesozoic and the current Cenozoic eras. All these eras experienced significant geological changes of the earth (Zhao, Sun,Wilde & Li 94). The Paleozoic Era The Paleozoic era, 570 to 245 million years ago, marked the end of the ice age and the beginning of early life on earth in the seas. It started after the Pannotia broke into smaller continents that drifted apart to later form the Pangaea. The period is subdivided into six geological periods. The Cambrian period marked the formation of shallow seas as the continents from pannotia drifted apart. There were five major continents during this period, Laurentia, Siberia, Baltica, Panthalassa and Gondwana continents (Mcphee 97). The oceans that were formed included the Iapetus, Khanty and Proto-Tethys oceans. Ordovician, the second period of the Paleozoic era, saw the continents on the southern part of the earth combine to form the Gondwana. During the period, Baltica drifted towards Laurentia and Avalonia drifted away from Gondwana and headed towards laurentia. Several oceans were deformed in the process while others were newly formed. After the ice age, the level of carbon dioxide in the atmosphere significantly fell. As Gondwana moved further towards the South Pole, extensive ice caps were formed on the continent. Siluronian is the period that followed Ordovician period. During this time, Gondwana drifted further to the south. Most of the glaciers that had been formed during the previous period melted and this caused a sudden rise in the sea levels (Gradstein, Ogg & Smith 67). The other continents had converged around the equator to form Euramerica. The Panthalassa Ocean was the largest ocean and the Ural Ocean was formed. The Devonian period followed. Over this period, the Euramerica drifted along the tropic of Capricorn while Pangaea started taking form along the equator. Gondwana remained intact in the south. Most of the land was submerged in water as the sea levels kept rising. Panthalassa was still the largest ocean, covering most parts of the northern hemisphere. During the Devonian period, life in the sea increased and some of the amphibians moved to the land. Small trees also started growing on the land. The carboniferous period succeeded the Devonian period. The period experienced a global lowering in temperatures (Levin 44). The sea levels had dropped and there was an extinction of most of the marine life in the seas. The Pangaea super continent was almost fully formed and there was a rapid formation of high mountains on it. The Panthalassa Ocean was still very large and the Paleo-Tethys Ocean had increased in volume as the continents drifted. Most of the other oceans shrunk and became too shallow. After the carboniferous period, the Permian period stepped in. This was the period when Pangaea fully formed. The Tethys Ocean started forming in the south. Most of the land on the super continent was a desert. The Permian period marked the end of the Paleozoic era. Mesozoic Era The Mesozoic Era was the period right after the Paleozoic Era. The Era started from 250 to 650 million years ago. During the era, the Pangaea super continent experienced rifting. The super continent then slowly broke in two continents, Laurasia in the north and Gondwana in the south. The two continents then started drifting away from each other. There were numerous volcanic activities that led to the formation of the western parts of North America. The Era was dominated by dinosaurs and other reptiles. The vegetation had covered most parts of the land. Most of the reptiles went extinct in the end of the era. The era has been divided into three periods, the Triassic, Jurassic and Cretaceous Periods (Rudwick 542). During the Triassic Period, Pangaea had fully formed in the equator region. The super continent experienced extensive rifting over this period. The Jurassic period then followed. This is the period when Pangaea broke into two parts after the extensive rifting of over the Triassic period. As the two continents drifted apart, the Tethys Ocean shrunk and Neotethys sea basin was formed. Both continents experienced very warm climates over the period. The continents were covered with vegetation and various animals. The Cretaceous period saw the complete breakup of the Pangaea super continent. The Atlantic Ocean increased in volume and Gondwana rifted into Australia, Antarctica and South America, all three continents moving away from Africa. This was followed by the formation of the Indian Ocean and the South Atlantic Ocean. The Tethys Sea continued to shrink. The sea levels rose as the rifting caused the formation of numerous sea mountains. Coal and chalk were formed in large deposits during this period (Hughes 23). The Cenozoic Era This is the era from 66 million years ago to date. In the beginning of the era, most of the continents have formed into their current shape. Gondwana had broken into Africa, Australia, South America, Antarctica and India, which later joined with Asia. The collision between the Indian plate and the Asian plate caused the formation of the Himalayas Mountains. The Mediterranean Sea was formed after the Tethys Sea shrunk. North America experienced a lot of volcanic activities during this Era. Over the Cenozoic era, the mammals evolved significantly. The vegetation cover on the various continents contained millions of different plant species. The era has been divided into two periods by geologists. These are the Paleogene and the Neogene Periods (Skinner & Porter 557). In the paleogene period, Laurasia was made up of Europe and Greenland and they were still connected. More mountains were formed in America as the rest of the continents drifted slowly towards their present positions. Australia and Antarctica were still connected during this period. Antarctica began to freeze and Australia still experienced the warm climate. Most of the water surrounding Antarctica froze into ice. In the middle of the period, Greenland pulled away from Europe and North America and each continent drifted away from the others. As Africa pushed further to the north, the Alps Mountains were formed in Europe. South America, which had been attached to Antarctica since the break of Pangaea, broke away from it and drifted towards North America (Alley & Frakes 135-144). The Neogene period followed the paleogene and it is from 23 million years ago to the present day. In the beginning of the period, the continents drifting motion continued. There have not been any significant physical changes in the continents in this period. The Tethys Sea was completely closed by the African continent in the beginning of the period. The sea levels in the world fell as the mountain rose higher. In the middle of the period, South America and North America formed a land bridge between them. Towards the recent 10,000 years, the sea levels have risen due to the melting of glaciers and ice caps (Stanley 280). The earth still experiences volcanic activities and other tectonic activities such as earthquakes as the plates drift and collide with each other. The current period exhibits a very wide range of complex animals and very extensive vegetations cover all over the continents. Each continent experiences a unique type of temperature depending on its position. Most of the glaciers on the continents have melted over the past couple of a thousand years and the sea level has been rising as the years go by. The period has also faced several animal and plants extinctions (Stanley 280). Conclusion The earth is approximately 4.6 million years old. It was formed along with the rest of the planets in the solar system and its life cycle has been almost identical to that of the other planets. It started in a gaseous state then cooled down to a molten form. The revolutions around the earth were very violent with many collisions that added up to the heating of the earth. As the collisions reduced in number and object size, the earth gradually cooled down, forming a thin crust surface. Further cooling caused the formation of water vapor which then formed clouds and rain started falling on earth. The crust surface then rifted and broke into different continents which then drifted apart and later collided to form super continents over and over and the trend continues to date. Many geologists have hypothesized the future geology of the earth but there is no certainty in the form that it will take as the current continents drift away from other continents and towards others. Works Cited Alley, N.F. & Frakes, L.A. "First known Cretaceous glaciation: Livingston Tillite, South Australia". Australian Journal of Earth Science 50.1 (2003):134–150. Print. Gradstein, Felix M., Ogg, James G. & Smith, Alan G. A Geologic Time Scale 2004. Cambridge: Cambridge University Press, 2005. Print. Hughes, T. “The case for creation of the North Pacific Ocean during the Mesozoic Era”. Palaeogeography, Palaeoclimatology, Palaeoecology 18.1 (1975): 1-43. Print. Levin, Harold L. "Time and Geology". The Earth Through Time. New Jersey: John Wiley & Sons, 2010. Print. McPhee, J. Basin and Range. New York: Farrar, Straus and Giroux, 1981. Print. Rudwick, Martin. “Worlds Before Adam”. The Reconstruction of Geohistory in the Age of Reform. 1.1 (2008): 539-545. Print. Sasso, Anne. “Crust Formed Early in Earth’s History”. Discovery. 29.1 (2008): 59. Print. Skinner, Brian J. & Porter, Stephen C.The Dynamic Earth: An Introduction to Physical Geology. New York: John Wiley & Sons, Inc., 1995. Print. Stanley, Steven M. 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