Geological Features
Plate tectonics theory, which is the modern theory of the motions of Earth’s layer, explains how geological features, such as mountain ranges, continents, and bodies of water move and form. An important aspect of plate tectonics theory is that the outer layer of the earth is divided into plates which move across the earth’s surface. “These plates move relative to each other, typically at rates of 2-4 inches per year. As the plates move, they interact along their boundaries” (Plate Tectonics). In other words, the formation of geological features occur at the plate boundaries which is where plates slide and interact. There are four types of plate boundaries: divergent boundaries, convergent boundaries, transform
boundaries, and plate-boundary zones. Plate tectonics theory explains how mountains are formed when two converging boundaries collide, causing the crust to lift and fold. Another important element of plate tectonics theory relates to mid-ocean ridges. Mid-ocean ridges are underwater mountain systems that are the boundaries between the plates, so they form the different plates. Mid-ocean ridges run throughout the world, which explains how each plate is formed, and how the plates move. As the New Book of Popular Science states, “Continents are carried along together with the surrounding seabed in huge plates” (New Book of Popular Science, 42). In other words, each continent is part of a plate that also includes part of an ocean. When divergence (two plates moving away from each other), occurs on continents, rift valleys form. When rift valleys separate completely, the area in-between fills up with water, forming a new ocean. Thus, rift valleys lead to creation of a new ocean. An example is the divergent boundary called the Mid-Atlantic Ridge. It is associated with seafloor spreading, causing the Atlantic Ocean to grow from a small lake into a vast ocean over 200 million years. Interestingly, plate tectonics theory doesn’t only help with understanding the world today, but also with predicting the future. For example, as US Geological Survey says, “East Africa may be the site of the Earth’s next major ocean” (This Dynamic Earth - The Story of Plate Tectonics). This means that because it is the site of a divergent boundary, there will one day be a rift valley. There are three plates that meet on the edge of Africa that are spreading apart, so if the spreading continues, a new ocean will be formed. In conclusion, the plate tectonics theory explains how mountains are built, continents move, and oceans form now and in the future.
WORKS CITED
The New Book of Popular Science. Vol. 2. N.p.: Scholastic Library Publishing, 2008. Print.
"Plate Tectonics." Britannica School. Encyclopedia Britannica, n.d. Web. 10 Dec. 2015. .
"This Dynamic Earth - The Story of Plate Tectonics." USGS. U.S. Government Printing Office, 3 Sept. 2015. Web. 4 Jan. 2016. .