Introduction to Geology - Assignment Example

Geology Geology: The study of earth and its processes, its history of origin and evolution, matter, composition and its effect on human is known as geology. It includes the study of the rocks, minerals, mountains, earthquakes, volcanoes, rivers and oceans and a wide variety of fields of study are included in this subject. Geology is completely a field oriented science and most of the study by the geologists is performed outdoors. It is a form of visual science where the hypothesis of the occurring phenomena needs to be explained by the geologists with the support of their findings during the study. The scientific method of geologists is to collect information, observe it , try a lot of different assumptions, read and discuss other peoples papers and grope their way toward greater certainty, or at least figure the answers with the best odds. A hypothesis drawn based on the quick observation needs to be verified by a number of experimental findings and research conclusions before it gets accepted as a theory. Canadian Shield: The Canadian shield, is a vast stretch of land covering the North America covered with thin layer of soil. It is also known as the Laurentian plateau. It is a collage of structural provinces composed of igneous rocks which are of volcanic origin. The areas covered in the shield have a deep, common, joined bedrock region in Eastern and Central Canada and in the North covering Great Lakes to the Arctic Ocean, and in the South covering part of USA. The Shield is one of the worlds richest areas in terms of mineral ores. It is filled with substantial deposits of nickel, gold, silver, and copper. Throughout the Shield there are many mining towns extracting these minerals. The Canadian Shield is a mosaic of structural provinces, each with characteristic internal structural trends and styles of folding. Volcanic eruptions and the movement of lava on the region lead to formation of folding on the surface. Internal Energy: The Earths internal heat source provides the energy for our dynamic planet, supplying it with the driving force for plate-tectonic motion, and for on-going catastrophic events such as earthquakes and volcanic eruptions. This internal heat energy was much greater in the early stages of the Earth than it is today, having accumulated rapidly by heat conversion associated with three separate processes, all of which were most intense during the first few hundred thousand years of the Earths history: (1) extraterrestrial impacts, (2) gravitational contraction of the Earths interior, and (3) the radioactive decay of unstable isotopes. Catastrophism It is a theory that states that the Earth’s crust has been formed as a result of some worldwide occurring disaster, by some sudden, short-lived and violent sequence of events. Catastrophism is supported by actual, recorded history. Nearly 300 ancient flood legends have survived the ravishment of time. Legends of a worldwide deluge, commonly known as the "Noachian Flood," are found in Europe, Asia, Africa, Australia, North American and South America. Sedimentary rock (sandstone, siltstone, shale, limestone, etc) is the result of moving water, laid down layer upon layer by hydrologic sorting. Animals whose fossil remains are found within those layers must have been caught in this running water to have been buried and preserved. The remains, as well as the rocks, would be sorted according to density. Continental Drift: It is the movement of the earth’s continents relative to each other. The theory states that continents move slowly about the earths surface, changing their positions relative to one another and to the poles of the earth. In the past the theory has been discussed but not generally accepted, most geologists believing the continents to be fixed in place and subject only to vertical movements, such as those observed during mountain uplift. Lithification: It is the process by which loose sediments are hardened to rocks. The phenomenon occurs in three ways compaction, recrystallization and cementation. This phenomenon eventually leads to reduction in re-transport and erosion. Rock Cycle: It is a cycle of group changes that occur in the formation of different kinds of rocks. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock. Igneous rock forms when magma cools and makes crystals. Magma is a hot liquid made of melted minerals. The minerals can form crystals when they cool. Igneous rock can form underground, where the magma cools slowly. Superposition of rocks: The Law of Superposition states that in a layered, depositional sequence (such as a series of sedimentary beds or lava flows), the material on which any layer is deposited is older than the layer itself. Thus, the layers are successively younger, going from bottom to top. Uniformitarianism: Catastrophism is contrary to Uniformitarianism, the accepted geological doctrine for over 150 years. Uniformitarianism states that current geologic processes, occurring at the same rates observed today, in the same manner, account for all of earths geological features. As present processes are thought to explain all past events, the Uniformitarianism slogan is "the present is the key to the past." Uniformitarianism ignores the possibility of past cataclysmic activity upon the surface of the earth.  Stratigraphy: It is the branch of geology that deals with the study of layering of rocks, primarily that of sedimentary and layered volcanic rocks. Stratigraphy includes two related subfields: lithologic stratigraphy or lithostratigraphy, and biologic stratigraphy orbiostratigraphy. Solidification: Igneous rocks are formed from the solidification of molten rock material. The process of solidification of lava from volcanic eruptions leading to the formation of igneous rocks is known as solidification. Lithosphere: It is the outermost rocky layer of the Earth comprising the crust and portion of the mantle. The lithosphere is broken into tectonic plates. The uppermost part of the lithosphere that chemically reacts to the atmosphere, hydrosphere and biosphere through the soil forming process is called the pedosphere. Uplift: It refers to the tectonic uplift. It is a geological process that occurs due to increase in elevation of tectonic plates. Abyssal plain: An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface.[1][2] They are among the flattest, smoothest and least explored regions on Earth. Continental shelf: The continental shelf of a coastal State comprises the submerged prolongation of the land territory of the coastal State - the seabed and subsoil of the submarine areas that extend beyond its territorial sea to the outer edge of the continental margin, or to a distance of 200 nautical miles where the outer edge of the continental margin does not extend up to that distance. Deep sea trench: A long, narrow, very deep, and asymmetrical depression of the sea floor, with relatively steep sides. Oceanic trenches characterize active margins at the ocean-basin–continent or ocean-basin–island-arc boundaries. They contain the greatest oceanic depths and are associated with the most active volcanism, largest negative gravity anomalies, most frequent shallow seismicity, and almost all of the intermediate and deep-focus earthquake activity. Mid-ocean ridge: It is the term used for underwater mountain system consisting of chain of mountain ranges, comprising valleys which are known as rifts, running along the spine and formed by tectonic plates. Seismic belt: Narrow geographic zone on the Earth’s surface along which most earthquake activity occurs. Subduction: Subduction is the process in which one plate is pushed downward beneath another plate into the underlying mantle when plates move towards each other.  The plate that is denser will slide under the thicker, less denseplate. Works cited 1) “The definition of the continental shelf and criteria for the establishment of its outer limits”,Commission on the Limits of the Continental Shelf (CLCS) :The continental shelf, n.d, n.p, web http://www.un.org/depts/los/clcs_new/continental_shelf_description.htm 2) Mc-graw hill science and technology dictionary : “ subduction”, web. 3) Alden Andrew, “Geological thinking : method of multiple hypothesis”, n.p., n.d, web. http://geology.about.com/od/history_of_geology/a/aa_geothinking.htm Read More